ETC 20695

Preliminary Information
AMD-K6
®
Processor
Data Sheet
Preliminary Information
© 1998 Advanced Micro Devices, Inc. All rights reserved.
Advanced Micro Devices, Inc. (“AMD”) reserves the right to make changes in its
products without notice in order to improve design or performance characteristics.
The information in this publication is believed to be accurate at the time of
publication, but AMD makes no representations or warranties with respect to the
accuracy or completeness of the contents of this publication or the information
contained herein, and reserves the right to make changes at any time, without notice.
AMD disclaims responsibility for any consequences resulting from the use of the
information included in this publication.
This publication neither states nor implies any representations or warranties of any
kind, including but not limited to, any implied warranty of merchantability or fitness
for a particular purpose. AMD products are not authorized for use as critical
components in life support devices or systems without AMD’s written approval. AMD
assumes no liability whatsoever for claims associated with the sale or use (including
the use of engineering samples) of AMD products, except as provided in AMD’s Terms
and Conditions of Sale for such products.
Trademarks
AMD, the AMD logo, and combinations thereof, K86, AMD-K5, and the AMD-K6 logo are trademarks, and RISC86
and AMD-K6 are registered trademarks of Advanced Micro Devices, Inc.
Microsoft and Windows are registered trademarks, and Windows NT is a trademark of Microsoft Corporation.
Netware is a registered trademark of Novell, Inc.
MMX is a trademark and Pentium is a registered trademark of Intel Corporation.
The TAP State Diagram is reprinted from IEEE Std 1149.1-1990 “IEEE Standard Test Access Port and Boundary-Scan
Architecture,” Copyright © 1990 by the Institute of Electrical and Electronics Engineers, Inc. The IEEE disclaims
any responsibility or liability resulting from the placement and use in the described manner. Information is reprinted
with the permission of the IEEE.
Other product names used in this publication are for identification purposes only and may be trademarks of their
respective companies.
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Contents
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
About This Data Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Part One
AMD-K6® Processor Family
1
AMD-K6® Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
Internal Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1
2.2
2.3
2.4
2.5
2.6
2.7
3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
AMD-K6® Processor Microarchitecture Overview . . . . . . . . . 7
Enhanced RISC86® Microarchitecture . . . . . . . . . . . . . . . . . . . 8
Cache, Instruction Prefetch, and Predecode Bits . . . . . . . . . 11
Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Prefetching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Predecode Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Instruction Fetch and Decode . . . . . . . . . . . . . . . . . . . . . . . . . 13
Instruction Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Instruction Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Centralized Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Execution Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Branch-Prediction Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Branch History Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Branch Target Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Return Address Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Branch Execution Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Software Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1
Contents
3
Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
General-Purpose Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Integer Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Segment Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Segment Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Instruction Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Floating-Point Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Floating-Point Register Data Types . . . . . . . . . . . . . . . . . . . . . 28
MMX™ Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
EFLAGS Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Control Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Debug Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Model-Specific Registers (MSR) . . . . . . . . . . . . . . . . . . . . . . . 37
iii
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
3.2
Memory Management Registers . . . . . . . . . . . . . . . . . . . . . . . 39
Task State Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Paging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Descriptors and Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Exceptions and Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Instructions Supported by the AMD-K6 Processor . . . . . . . . 49
4
Logic Symbol Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5
Signal Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13
5.14
5.15
5.16
5.17
5.18
5.19
5.20
5.21
5.22
5.23
5.24
5.25
5.26
5.27
5.28
5.29
5.30
5.31
5.32
5.33
5.34
5.35
5.36
5.37
5.38
iv
A20M# (Address Bit 20 Mask) . . . . . . . . . . . . . . . . . . . . . . . . . 79
A[31:3] (Address Bus) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
ADS# (Address Strobe) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
ADSC# (Address Strobe Copy) . . . . . . . . . . . . . . . . . . . . . . . . 81
AHOLD (Address Hold) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
AP (Address Parity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
APCHK# (Address Parity Check) . . . . . . . . . . . . . . . . . . . . . . 84
BE[7:0]# (Byte Enables) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
BF[2:0] (Bus Frequency) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
BOFF# (Backoff) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
BRDY# (Burst Ready) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
BRDYC# (Burst Ready Copy) . . . . . . . . . . . . . . . . . . . . . . . . . 89
BREQ (Bus Request) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
CACHE# (Cacheable Access) . . . . . . . . . . . . . . . . . . . . . . . . . 90
CLK (Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D/C# (Data/Code) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D[63:0] (Data Bus) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
DP[7:0] (Data Parity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
EADS# (External Address Strobe) . . . . . . . . . . . . . . . . . . . . . 94
EWBE# (External Write Buffer Empty) . . . . . . . . . . . . . . . . . 95
FERR# (Floating-Point Error) . . . . . . . . . . . . . . . . . . . . . . . . 96
FLUSH# (Cache Flush) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
HIT# (Inquire Cycle Hit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
HITM# (Inquire Cycle Hit To Modified Line) . . . . . . . . . . . . 98
HLDA (Hold Acknowledge) . . . . . . . . . . . . . . . . . . . . . . . . . . 99
HOLD (Bus Hold Request) . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
IGNNE# (Ignore Numeric Exception) . . . . . . . . . . . . . . . . . 100
INIT (Initialization) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
INTR (Maskable Interrupt) . . . . . . . . . . . . . . . . . . . . . . . . . . 102
INV (Invalidation Request) . . . . . . . . . . . . . . . . . . . . . . . . . . 102
KEN# (Cache Enable) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
LOCK# (Bus Lock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
M/IO# (Memory or I/O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
NA# (Next Address) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
NMI (Non-Maskable Interrupt) . . . . . . . . . . . . . . . . . . . . . . . 106
PCD (Page Cache Disable) . . . . . . . . . . . . . . . . . . . . . . . . . . 107
PCHK# (Parity Check) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
PWT (Page Writethrough) . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Contents
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
5.39
5.40
5.41
5.42
5.43
5.44
5.45
5.46
5.47
5.48
5.49
5.50
5.51
5.52
6
Bus Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.1
6.2
6.3
6.4
6.5
Contents
RESET (Reset) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
RSVD (Reserved) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
SCYC (Split Cycle) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
SMI# (System Management Interrupt) . . . . . . . . . . . . . . . . 111
SMIACT# (System Management Interrupt Active) . . . . . . 112
STPCLK# (Stop Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
TCK (Test Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
TDI (Test Data Input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TDO (Test Data Output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TMS (Test Mode Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TRST# (Test Reset) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
VCC2DET (VCC2 Detect) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
W/R# (Write/Read) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
WB/WT# (Writeback or Writethrough) . . . . . . . . . . . . . . . . 116
Timing Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Bus State Machine Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 123
Idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Data-NA# Requested. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Pipeline Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Pipeline Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Memory Reads and Writes . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Single-Transfer Memory Read and Write . . . . . . . . . . . . . . . 126
Misaligned Single-Transfer Memory Read and Write . . . . . 128
Burst Reads and Pipelined Burst Reads . . . . . . . . . . . . . . . . 130
Burst Writeback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
I/O Read and Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Basic I/O Read and Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Misaligned I/O Read and Write . . . . . . . . . . . . . . . . . . . . . . . 135
Inquire and Bus Arbitration Cycles . . . . . . . . . . . . . . . . . . . 136
Hold and Hold Acknowledge Cycle . . . . . . . . . . . . . . . . . . . . 136
HOLD-Initiated Inquire Hit to Shared or Exclusive
Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
HOLD-Initiated Inquire Hit to Modified Line . . . . . . . . . . . 140
AHOLD-Initiated Inquire Miss. . . . . . . . . . . . . . . . . . . . . . . . 142
AHOLD-Initiated Inquire Hit to Shared or Exclusive
Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
AHOLD-Initiated Inquire Hit to Modified Line . . . . . . . . . . 146
AHOLD Restriction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Bus Backoff (BOFF#) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Locked Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Basic Locked Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Locked Operation with BOFF# Intervention . . . . . . . . . . . . 154
Interrupt Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
v
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
6.6
Special Bus Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Basic Special Bus Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Shutdown Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Stop Grant and Stop Clock States . . . . . . . . . . . . . . . . . . . . . 161
INIT-Initiated Transition from Protected Mode to
Real Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
7
Power-on Configuration and Initialization . . . . . . . . . . . . . . 167
7.1
7.2
7.3
7.4
8
Cache Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
9
MESI States in the Data Cache . . . . . . . . . . . . . . . . . . . . . . . 172
Predecode Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Cache Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Cache-Related Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Cache Disabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Cache-Line Fills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Cache-Line Replacements . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Write Allocate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Write to a Cacheable Page . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Write to a Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Write Allocate Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Descriptions of the Logic Mechanisms and Conditions . . . . 180
Prefetching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Cache States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Cache Coherency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Inquire Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Internal Snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
FLUSH# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
WBINVD and INVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Cache-Line Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Cache Snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Writethrough vs. Writeback Coherency States . . . . . . . . . . 187
A20M# Masking of Cache Accesses . . . . . . . . . . . . . . . . . . . 187
Floating-Point and Multimedia Execution Units . . . . . . . . . 189
9.1
vi
Signals Sampled During the Falling Transition
of RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
FLUSH# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
BF[2:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
BRDYC# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
RESET Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
State of Processor After RESET . . . . . . . . . . . . . . . . . . . . . . 168
Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
State of Processor After INIT . . . . . . . . . . . . . . . . . . . . . . . . 170
Floating-Point Execution Unit . . . . . . . . . . . . . . . . . . . . . . . 189
Handling Floating-Point Exceptions . . . . . . . . . . . . . . . . . . . 189
External Logic Support of Floating-Point Exceptions . . . . . 189
Contents
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
9.2
9.3
10
System Management Mode (SMM) . . . . . . . . . . . . . . . . . . . . 193
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
11
11.4
11.5
Built-In Self-Test (BIST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Tri-State Test Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Boundary-Scan Test Access Port (TAP) . . . . . . . . . . . . . . . . 205
Test Access Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
TAP Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
TAP Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
TAP Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
TAP Controller State Machine . . . . . . . . . . . . . . . . . . . . . . . . 212
L1 Cache Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Debug Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Debug Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
12.1
12.2
12.3
12.4
Contents
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
SMM Operating Mode and Default Register Values . . . . . 193
SMM State-Save Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
SMM Revision Identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
SMM Base Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Halt Restart Slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
I/O Trap Dword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
I/O Trap Restart Slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Exceptions, Interrupts, and Debug in SMM . . . . . . . . . . . . 202
Test and Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
11.1
11.2
11.3
12
Multimedia Execution Unit . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Floating-Point and MMX Instruction Compatibility . . . . . . 191
Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
FERR# and IGNNE# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Halt State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Enter Halt State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Exit Halt State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Stop Grant State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Enter Stop Grant State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Exit Stop Grant State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Stop Grant Inquire State . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Enter Stop Grant Inquire State . . . . . . . . . . . . . . . . . . . . . . . 226
Exit Stop Grant Inquire State . . . . . . . . . . . . . . . . . . . . . . . . 226
Stop Clock State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Enter Stop Clock State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Exit Stop Clock State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
vii
Preliminary Information
AMD-K6® Processor Data Sheet
13
Power and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
13.1
13.2
13.3
14
16.3
16.4
16.5
16.6
16.7
16.8
16.9
CLK Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . 241
Clock Switching Characteristics for 66-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Clock Switching Characteristics for 60-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Valid Delay, Float, Setup, and Hold Timings . . . . . . . . . . . 243
Output Delay Timings for 66-MHz Bus Operation . . . . . . . 244
Input Setup and Hold Timings for 66-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Output Delay Timings for 60-MHz Bus Operation . . . . . . . 248
Input Setup and Hold Timings for 60-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
RESET and Test Signal Timing . . . . . . . . . . . . . . . . . . . . . . 252
Thermal Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
17.1
17.2
Package Thermal Specifications . . . . . . . . . . . . . . . . . . . . . . 259
Heat Dissipation Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
Measuring Case Temperature . . . . . . . . . . . . . . . . . . . . . . . . 262
Layout and Airflow Considerations . . . . . . . . . . . . . . . . . . . 262
Voltage Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Airflow Management in a System Design . . . . . . . . . . . . . . . 264
18
Pin Description Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
19
Pin Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
20
Package Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
20.1
21
viii
Selectable Drive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
I/O Buffer Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
I/O Model Application Note . . . . . . . . . . . . . . . . . . . . . . . . . 239
I/O Buffer AC and DC Characteristics . . . . . . . . . . . . . . . . . 239
Signal Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . 241
16.1
16.2
17
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Absolute Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
I/O Buffer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
15.1
15.2
15.3
15.4
16
Power Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Decoupling Recommendations . . . . . . . . . . . . . . . . . . . . . . . 230
Pin Connection Requirements . . . . . . . . . . . . . . . . . . . . . . . 231
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
14.1
14.2
14.3
14.4
15
20695H/0—March 1998
321-Pin Staggered CPGA Package Specification . . . . . . . . 271
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Contents
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Part Two
AMD-K6 Processor Model 7
22
AMD-K6 Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
23
Internal Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
24
Software Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
24.1
24.2
Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
Model-Specific Registers (MSR) . . . . . . . . . . . . . . . . . . . . . . 281
Instructions Supported by the AMD-K6 Processor . . . . . . . 283
25
Logic Symbol Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
26
Signal Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
26.1
26.2
VCC2DET (VCC2 Detect) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
VCC2H/L# (VCC2 High/Low) . . . . . . . . . . . . . . . . . . . . . . . . . 287
27
Bus Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
28
Power-on Configuration and Initialization . . . . . . . . . . . . . . 291
28.1
State of Processor After RESET . . . . . . . . . . . . . . . . . . . . . . 291
Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
29
Cache Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
30
Floating-Point and Multimedia Execution Units . . . . . . . . . 295
31
System Management Mode (SMM) . . . . . . . . . . . . . . . . . . . . 297
32
Test and Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
32.1
32.2
Tri-State Test Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Boundary-Scan Test Access Port (TAP) . . . . . . . . . . . . . . . . 299
TAP Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
33
Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
34
Power and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
34.1
35
36
Power Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
35.1
35.2
35.3
35.4
Contents
275
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Absolute Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
I/O Buffer Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
ix
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
37
Signal Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . 311
38
Thermal Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
38.1
Package Thermal Specifications . . . . . . . . . . . . . . . . . . . . . . 313
39
Pin Description Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
40
Pin Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
41
Package Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
42
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
x
Contents
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
List of Figures
Part One
AMD-K6 Processor Family
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
List of Figures
3
AMD-K6 Processor Block Diagram . . . . . . . . . . . . . . . . . . . . . . . 11
Cache Sector Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
The Instruction Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
AMD-K6 Processor Decode Logic . . . . . . . . . . . . . . . . . . . . . . . . 14
AMD-K6 Processor Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
EAX Register with 16-Bit and 8-Bit Name Components. . . . . . 22
Integer Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Segment Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Segment Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Floating-Point Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
FPU Status Word Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
FPU Control Word Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
FPU Tag Word Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Packed Decimal Data Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Precision Real Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
MMX Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
MMX Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
EFLAGS Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Control Register 4 (CR4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Control Register 3 (CR3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Control Register 2 (CR2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Control Register 1 (CR1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Control Register 0 (CR0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Debug Register DR7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Debug Register DR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Debug Registers DR5 and DR4. . . . . . . . . . . . . . . . . . . . . . . . . . 35
Debug Registers DR3, DR2, DR1, and DR0. . . . . . . . . . . . . . . . 36
Machine-Check Address Register (MCAR) . . . . . . . . . . . . . . . . 37
Machine-Check Type Register (MCTR) . . . . . . . . . . . . . . . . . . . 38
Test Register 12 (TR12). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Time Stamp Counter (TSC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Write Handling Control Register (WHCR) . . . . . . . . . . . . . . . . 39
Memory Management Registers . . . . . . . . . . . . . . . . . . . . . . . . . 40
Task State Segment (TSS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
xi
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
Figure 43.
Figure 44.
Figure 45.
4-Kbyte Paging Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4-Mbyte Paging Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Page Directory Entry 4-Kbyte Page Table (PDE) . . . . . . . . . . . 44
Page Directory Entry 4-Mbyte Page Table (PDE) . . . . . . . . . . 44
Page Table Entry (PTE). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Application Segment Descriptor . . . . . . . . . . . . . . . . . . . . . . . . 46
System Segment Descriptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Gate Descriptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Waveform Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Bus State Machine Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Non-Pipelined Single-Transfer Memory Read/Write and
Write Delayed by EWBE# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Misaligned Single-Transfer Memory Read and Write . . . . . . 129
Burst Reads and Pipelined Burst Reads . . . . . . . . . . . . . . . . . 131
Burst Writeback due to Cache-Line Replacement . . . . . . . . . 133
Basic I/O Read and Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Misaligned I/O Transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Basic HOLD/HLDA Operation . . . . . . . . . . . . . . . . . . . . . . . . . 137
HOLD-Initiated Inquire Hit to Shared or Exclusive Line . . . 139
HOLD-Initiated Inquire Hit to Modified Line. . . . . . . . . . . . . 141
AHOLD-Initiated Inquire Miss . . . . . . . . . . . . . . . . . . . . . . . . . 143
AHOLD-Initiated Inquire Hit to Shared or
Exclusive Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
AHOLD-Initiated Inquire Hit to Modified Line . . . . . . . . . . . 147
AHOLD Restriction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
BOFF# Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Basic Locked Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Locked Operation with BOFF# Intervention. . . . . . . . . . . . . . 155
Interrupt Acknowledge Operation . . . . . . . . . . . . . . . . . . . . . . 157
Basic Special Bus Cycle (Halt Cycle) . . . . . . . . . . . . . . . . . . . . 159
Shutdown Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Stop Grant and Stop Clock Modes, Part 1 . . . . . . . . . . . . . . . . 162
Stop Grant and Stop Clock Modes, Part 2 . . . . . . . . . . . . . . . . 163
INIT-Initiated Transition from Protected Mode to
Real Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Cache Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Cache Sector Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Write Handling Control Register (WHCR) . . . . . . . . . . . . . . . 179
Write Allocate Logic Mechanisms and Conditions . . . . . . . . . 180
External Logic for Supporting Floating-Point
Exceptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Figure 46.
Figure 47.
Figure 48.
Figure 49.
Figure 50.
Figure 51.
Figure 52.
Figure 53.
Figure 54.
Figure 55.
Figure 56.
Figure 57.
Figure 58.
Figure 59.
Figure 60.
Figure 61.
Figure 62.
Figure 63.
Figure 64.
Figure 65.
Figure 66.
Figure 67.
Figure 68.
Figure 69.
Figure 70.
Figure 71.
xii
List of Figures
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Figure 72.
Figure 73.
Figure 74.
Figure 75.
Figure 76.
Figure 77.
Figure 78.
Figure 79.
Figure 80.
Figure 81.
Figure 82.
Figure 83.
Figure 84.
Figure 85.
Figure 86.
Figure 87.
Figure 88.
Figure 89.
Figure 90.
Figure 91.
Figure 92.
Figure 93.
Figure 94.
Figure 95.
Figure 96.
Figure 97.
Figure 98.
Figure 99.
Figure 100.
Figure 101.
SMM Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
TAP State Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Debug Register DR7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Debug Register DR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
Debug Registers DR5 and DR4. . . . . . . . . . . . . . . . . . . . . . . . . 218
Debug Registers DR3, DR2, DR1, and DR0. . . . . . . . . . . . . . . 219
Clock Control State Transitions . . . . . . . . . . . . . . . . . . . . . . . . 228
Suggested Component Placement . . . . . . . . . . . . . . . . . . . . . . 230
K6STD Pulldown V/I Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
K6STD Pullup V/I Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
CLK Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Diagrams Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Output Valid Delay Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Maximum Float Delay Timing . . . . . . . . . . . . . . . . . . . . . . . . . 255
Input Setup and Hold Timing . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Reset and Configuration Timing . . . . . . . . . . . . . . . . . . . . . . . 256
TCK Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
TRST# Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Test Signal Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Thermal Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
Power Consumption vs. Thermal Resistance . . . . . . . . . . . . . 260
Processor Heat Dissipation Path . . . . . . . . . . . . . . . . . . . . . . . 261
Measuring Case Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . 262
Voltage Regulator Placement . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Airflow for a Heatsink with Fan . . . . . . . . . . . . . . . . . . . . . . . . 263
Airflow Path in a Dual-fan System . . . . . . . . . . . . . . . . . . . . . . 264
Airflow Path in an ATX Form-Factor System . . . . . . . . . . . . . 265
AMD-K6 Processor Top-Side View . . . . . . . . . . . . . . . . . . . . . . 267
AMD-K6 Processor Pin-Side View . . . . . . . . . . . . . . . . . . . . . . 268
321-Pin Staggered CPGA Package Specification . . . . . . . . . . 272
Part Two
AMD-K6 Processor Model 7
Figure 102.
Figure 103.
Figure 104.
Figure 105.
List of Figures
275
Extended Feature Enable Register (EFER) . . . . . . . . . . . . . . 282
SYSCALL/SYSRET Target Address Register (STAR) . . . . . . 283
AMD-K6 Processor Model 7 Top-Side View. . . . . . . . . . . . . . . 315
AMD-K6 Processor Model 7 Pin-Side View . . . . . . . . . . . . . . . 316
xiii
Preliminary Information
AMD-K6® Processor Data Sheet
xiv
20695H/0—March 1998
List of Figures
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
List of Tables
Part One
AMD-K6 Processor Family
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table 15.
Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
Table 21.
Table 22.
Table 23.
Table 24.
Table 25.
Table 26.
Table 27.
Table 28.
Table 29.
Table 30.
Table 31.
Table 32.
Table 33.
Table 34.
Table 35.
Table 36.
List of Tables
3
Execution Latency and Throughput of Execution
Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
General-Purpose Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
General-Purpose Register Dword, Word, and Byte
Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Segment Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Model-Specific Registers (MSRs) . . . . . . . . . . . . . . . . . . . . . . . . 37
Memory Management Registers . . . . . . . . . . . . . . . . . . . . . . . . . 39
Application Segment Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
System Segment and Gate Types . . . . . . . . . . . . . . . . . . . . . . . . 47
Summary of Exceptions and Interrupts . . . . . . . . . . . . . . . . . . . 48
Integer Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Floating-Point Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
MMX Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Processor-to-Bus Clock Ratios. . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Input Pin Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Output Pin Float Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Input/Output Pin Float Conditions . . . . . . . . . . . . . . . . . . . . . . 118
Test Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Bus Cycle Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Special Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Bus-Cycle Order During Misaligned Transfers . . . . . . . . . . . . 128
A[4:3] Address-Generation Sequence During Bursts . . . . . . . 130
Bus-Cycle Order During Misaligned I/O Transfers . . . . . . . . . 135
Interrupt Acknowledge Operation Definition. . . . . . . . . . . . . 156
Encodings For Special Bus Cycles . . . . . . . . . . . . . . . . . . . . . . 158
Output Signal State After RESET . . . . . . . . . . . . . . . . . . . . . . 168
Register State After RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
PWT Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
PCD Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
CACHE# Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Data Cache States for Read and Write Accesses . . . . . . . . . . 182
Cache States for Inquiries, Snoops, Invalidation, and
Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Snoop Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Initial State of Registers in SMM . . . . . . . . . . . . . . . . . . . . . . . 195
SMM State-Save Area Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
SMM Revision Identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
I/O Trap Dword Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 200
xv
Preliminary Information
AMD-K6® Processor Data Sheet
Table 37.
Table 38.
Table 39.
Table 40.
Table 41.
Table 42.
Table 43.
Table 44.
Table 45.
Table 46.
Table 47.
Table 48.
Table 49.
Table 50.
Table 51.
Table 52.
Table 53.
Table 54.
Table 55.
Table 56.
Table 57.
Table 58.
20695H/0—March 1998
I/O Trap Restart Slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Boundary Scan Bit Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 209
Device Identification Register . . . . . . . . . . . . . . . . . . . . . . . . . 210
Supported Tap Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
DR7 LEN and RW Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 221
Operating Ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Absolute Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Typical and Maximum Power Dissipation . . . . . . . . . . . . . . . . 235
A[20:3], ADS#, HITM#, and W/R# Strength Selection . . . . . . 237
CLK Switching Characteristics for 66-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
CLK Switching Characteristics for 60-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Output Delay Timings for 66-MHz Bus Operation . . . . . . . . . 244
Input Setup and Hold Timings for 66-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Output Delay Timings for 60-MHz Bus Operation . . . . . . . . . 248
Input Setup and Hold Timings for 60-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
RESET and Configuration Signals (60-MHz and 66-MHz
Operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
TCK Waveform and TRST# Timing at 25 MHz . . . . . . . . . . . . 253
Test Signal Timing at 25 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . 253
Package Thermal Specification . . . . . . . . . . . . . . . . . . . . . . . . 259
321-Pin Staggered CPGA Package Specification . . . . . . . . . . 271
Valid Ordering Part Number Combinations . . . . . . . . . . . . . . 273
Part Two
AMD-K6 Processor Model 7
Table 59.
Table 60.
Table 61.
Table 62.
Table 63.
Table 64.
Table 65.
Table 66.
Table 67.
Table 68.
Table 69.
Table 70.
Table 71.
Table 72.
xvi
275
Model-Specific Registers (MSRs) . . . . . . . . . . . . . . . . . . . . . . . 282
Extended Feature Enable Register (EFER) Definition . . . . . 282
SYSCALL/SYSRET Target Address Register (STAR)
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Integer Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Output Pin Float Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
Output Signal State After RESET . . . . . . . . . . . . . . . . . . . . . . 291
Register State After RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Device Identification Register . . . . . . . . . . . . . . . . . . . . . . . . . 300
Operating Ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Absolute Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Typical and Maximum Power Dissipation . . . . . . . . . . . . . . . . 307
Package Thermal Specification . . . . . . . . . . . . . . . . . . . . . . . . 313
Valid Ordering Part Number Combinations . . . . . . . . . . . . . . 321
List of Tables
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Revision History
Date
Rev
Description
June 1997
E
Replaced overbar with # to identify active-Low signals.
June 1997
E
Corrected description in “Write Allocate” on page 177.
June 1997
E
Revised latency and throughput information in Table 1, “Execution Latency and Throughput of
Execution Units,” on page 18.
June 1997
E
Updated Figure 79, “Suggested Component Placement,” on page 230 of Chapter 13, “Power and
Grounding”.
Sept 1997
F
Unreleased version.
March 1998
G
Divided book into Part 1 and Part 2. Part 1 provides information about the AMD-K6® processor
family (Model 6 and Model 7) and Part 2 provides information specific to the AMD-K6 processor
Model 7 (0.25-micron process technology).
March 1998
G
Added Figure 17, “MMX™ Data Types,” on page 30 in Chapter 3, “Software Environment”.
March 1998
G
Qualified conditions under which Write Allocate occurs in the memory area between 640 Kbytes
and 1 Mbyte in “Write Allocate Limit” on page 178 of Chapter 8, “Cache Organization”.
March 1998
G
Changed power dissipation specifications for Stop Grant State and Stop Clock State for 166MHz,
200MHz, and 233MHz components in Table 45, “Typical and Maximum Power Dissipation,” on
page 235, and Table 56, “Package Thermal Specification,” on page 259.
March 1998
G
Removed all references to Write KEN# Control Register (WKCR) from Chapter 3, “Software
Environment”, Chapter 5, “Signal Descriptions”, and Chapter 8, “Cache Organization”.
March 1998
G
Added top-side view pin description diagram. See Figure 99, “AMD-K6® Processor Top-Side
View,” on page 267.
March 1998
G
Added voltage detection pin to diagram in Chapter 4, “Logic Symbol Diagram”.
March 1998
G
Modified flatness specification (symbol f) in Table 57, “321-Pin Staggered CPGA Package
Specification,” on page 271.
March 1998
G
Corrected Figure 44, “Bus State Machine Diagram,” on page 123 in Chapter 6, “Bus Cycles” to
accurately show the direct transition from the Pipeline Data state to the Data-NA# Requested
state.
March 1998
G
Corrected list of internal resources tested during BIST in Chapter 11, “Test and Debug” on page
203.
March 1998
G
Revised Figure 92, “Power Consumption vs. Thermal Resistance,” on page 260 in Chapter 17,
“Thermal Design”.
March 1998
H
Revised signal description of VCC2H/L# on page 287 in Chapter 26, “Signal Descriptions”.
Revision History
xvii
Preliminary Information
AMD-K6® Processor Data Sheet
xviii
20695H/0—March 1998
Revision History
Preliminary Information
20695H/0—March 1998
AMD-K6® Processor Data Sheet
About This Data Sheet
The AMD-K6® Processor Data Sheet supports the Model 6 and Model 7 versions of
the AMD-K6 processor family. Model 6 refers to the AMD-K6 manufactured in the
0.35-micron process technology and Model 7 refers to the AMD-K6 manufactured in
the 0.25-micron process technology. The data sheet is divided into two parts. Part One
(chapters 1–21) contains information that pertains to the entire AMD-K6 desktop
family and information specific to the Model 6. Part Two (chapters 22–42) contains
information regarding new specifications and differences that pertain only to Model
7 as compared to Model 6.
About This Data Sheet
1
Preliminary Information
AMD-K6® Processor Data Sheet
2
20695H/0—March 1998
About This Data Sheet
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Part One
AMD-K6 ®
Processor Family
The AMD-K6® Processor Data Sheet supports the Model 6 and
Model 7 versions of the AMD-K6 processor family. Model 6
refers to the AMD-K6 manufactured with 0.35-micron process
technology and Model 7 refers to the AMD-K6 manufactured
with 0.25-micron process technology. Part One (chapters 1–21)
contains information that pertains to the entire AMD-K6
desktop family and information specific to Model 6.
Part One
AMD-K6® Processor Family
3
Preliminary Information
AMD-K6® Processor Data Sheet
4
20695H/0—March 1998
AMD-K6® Processor Family
Part One
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
AMD-K6® Processor
1
■
■
■
■
■
■
■
■
Advanced 6-Issue RISC86® Superscalar Microarchitecture
◆ Seven parallel specialized execution units
◆ Multiple sophisticated x86-to-RISC86 instruction decoders
◆ Advanced two-level branch prediction
◆ Speculative execution
◆ Out-of-order execution
◆ Register renaming and data forwarding
◆ Issues up to six RISC86 instructions per clock
Large On-Chip Split 64-Kbyte Level-One (L1) Cache
◆ 32-Kbyte instruction cache with additional predecode cache
◆ 32-Kbyte writeback dual-ported data cache
◆ MESI protocol support
High-Performance IEEE 754-Compatible and 854-Compatible Floating-Point Unit
High-Performance Industry-Standard MMX™ Instructions
321-Pin Ceramic Pin Grid Array (CPGA) Package (Socket 7 Compatible)
Industry-Standard System Management Mode (SMM)
IEEE 1149.1 Boundary Scan
Full x86 Binary Software Compatibility
As the next generation in the AMD K86™ family of x86 processors, the innovative
AMD-K6 processor brings industry-leading performance to PC systems running the
extensive installed base of x86 software. In addition, its socket 7 compatible, 321-pin
Ceramic Pin Grid Array (CPGA) package enables the AMD-K6 to reduce
time-to-market by leveraging today’s cost-effective infrastructure to deliver a
superior price/performance PC solution.
To provide state-of-the-art performance, the AMD-K6 processor incorporates the
innovative and efficient RISC86 microarchitecture, a large 64-Kbyte level-one cache
(32-Kbyte dual-ported data cache, 32-Kbyte instruction cache with predecode data), a
powerful IEEE 754-compatible and 854-compatible floating-point execution unit, and
a high-performance multimedia execution unit for executing industry-standard MMX
instructions. These features have been combined to deliver industry leadership in
16-bit and 32-bit performance, providing exceptional performance for both Windows®
95 and Windows NT™ software bases.
Chapter 1
AMD-K6® Processor
5
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The AMD-K6 processor’s RISC86 microarchitecture is a decoupled decode/execution
superscalar design that implements state-of-the-art design techniques to achieve
leading-edge performance. Advanced design techniques implemented in the AMD-K6
include multiple x86 instruction decode, single-clock internal RISC operations, seven
execution units that support superscalar operation, out-of-order execution, data
forwarding, speculative execution, and register renaming. In addition, the processor
supports the industry’s most advanced branch prediction logic by implementing an
8192-entry branch history table, the industry’s only branch target cache, and a return
address stack, which combine to deliver better than a 95% prediction rate. These
design techniques enable the AMD-K6 processor to issue, execute, and retire
multiple x86 instructions per clock, resulting in excellent scaleable performance.
The AMD-K6 processor is fully x86 binary code compatible. AMD’s extensive
experience through four generations of x86 processors has been carefully integrated
into the AMD-K6 to provide complete compatibility with Windows 95, Windows 3.x,
Windows NT, DOS, OS/2, Unix, Solaris, NetWare® , Vines, and other leading x86
operating systems and applications. The AMD-K6 processor is Socket 7 compatible,
allowing the processor to be quickly and easily integrated into a mature and
cost-effective industry-standard infrastructure of motherboards, chipsets, power
supplies, and thermal designs.
AMD has designed, manufactured, and delivered over 50 million Microsoft ®
Windows-compatible processors in the last five years alone. The AMD-K6 processor is
the next generation in this long line of processors. With its combination of
state-of-the-art features, industry-leading performance, high-performance
multimedia engine, full x86 compatibility, and low-cost infrastructure, the AMD-K6 is
the superior choice for mainstream personal computers.
6
AMD-K6® Processor
Chapter 1
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
2
2.1
Internal Architecture
Introduction
The AMD-K6 processor implements advanced design techniques
k n ow n a s t h e R I S C8 6 m i c ro a rch it e c t u re . The R I S C8 6
microarchitecture is a decoupled decode/execution design
approach that yields superior sixth-generation performance for
x86-based software. This chapter describes the techniques used
and the functional elements of the RISC86 microarchitecture.
2.2
AMD-K6® Processor Microarchitecture Overview
When discussing processor design, it is important to understand
t h e t e r m s a r ch i t e c t u re , m i c r o a r ch i t e c t u re , a nd d e s i g n
implementation. The term architecture refers to the instruction
set and features of a processor that are visible to software
p rog ra m s r u n n ing o n t h e p ro c e s so r. The a rchi t ec t ure
de termines w hat software the processor can run. The
architecture of the AMD-K6 processor is the industry-standard
x86 instruction set.
The term microarchitecture refers to the design techniques used
in the processor to reach the target cost, performance, and
functionality goals. The AMD-K6 is based on a sophisticated
RISC core known as the Enhanced RISC86 microarchitecture.
The Enhanced RISC86 microarchitecture is an advanced,
second-order decoupled decode/execution design approach that
enables industry-leading performance for x86-based software.
The term design implementation refers to the actual logic and
circuit designs from which the processor is created according to
the microarchitecture specifications.
Chapter 2
Internal Architecture
7
Preliminary Information
AMD-K6® Processor Data Sheet
Enhanced RISC86®
Microarchitecture
20695H/0—March 1998
Th e E n h anced RISC86 mi croarchi tecture defi nes t h e
characteristics of the AMD-K6. The innovative RISC86
microarchitecture approach implements the x86 instruction set
by internally translating x86 instructions into RISC86
operations. These RISC86 operations were specially designed to
include direct support for the x86 instruction set while
observing the RISC performance principles of fixed length
encoding, regularized instruction fields, and a large register
set. The Enhanced RISC86 microarchitecture used in the
AMD-K6 enables higher processor core performance and
promotes straightforward extensibility in future designs.
Instead of directly executing complex x86 instructions, which
have lengths of 1 to 15 bytes, the AMD-K6 processor executes
the simpler and easier fixed-length RISC86 opcodes, while
maintaining the instruction coding efficiencies found in x86
programs.
Th e A MD -K 6 p ro c e s so r c o n t a i n s p ara l l el d e c o d e rs , a
centralized RISC86 operation scheduler, and seven execution
units that support superscalar operation—multiple decode,
execution, and retirement—of x86 instructions. These elements
are packed into an aggressive and highly efficient six-stage
pipeline.
Decoders. Decoding of the x86 instructions begins when the
on-chip instruction cache is filled. Predecode logic determines
the length of an x86 instruction on a byte-by-byte basis. This
p re d e c o d e i n fo r m a t i o n i s s t o re d , a l o n g w i t h t h e x 8 6
instructions, in the instruction cache, to be used later by the
decoders. The decoders translate on-the-fly, with no additional
latency, up to two x86 instructions per clock into RISC86
operations.
Note: In this chapter, “clock” refers to a processor clock.
The AMD-K6 processor categorizes x86 instructions into three
types of decodes—short, long and vector. The decoders process
either two short, one long, or one vector decode at a time. The
three types of decodes have the following characteristics:
■
Short decodes—x86 instructions less than or equal to seven
bytes in length
■
Long decodes—x86 instructions less than or equal to 11
bytes in length
■
Vector decodes—complex x86 instructions
8
Internal Architecture
Chapter 2
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Short and long decodes are processed completely within the
decoders. Vector decodes are started by the decoders and then
completed by fetched sequences from an on-chip ROM. After
decoding, the RISC86 operations are delivered to the scheduler
for dispatching to the executions units.
Scheduler/Instruction Control Unit. The centraliz ed scheduler or
buffer is managed by the Instruction Control Unit (ICU). The
ICU buffers and manages up to 24 RISC86 operations at a time.
This equals from 6 to 12 x86 instructions. This buffer size (24) is
perfectly matched to the processor’s six-stage RISC86 pipeline
and seven parallel execution units. The scheduler accepts as
many as four RISC86 operations at a time from the decoders.
The ICU is capable of simultaneously issuing up to six RISC86
operations at a time to the execution units. This consists of the
following types of operations:
■
■
■
■
■
■
Memory load operation
Memory store operation
Complex integer or MMX register operation
Simple integer register operation
Floating-point register operation
Branch condition evaluation
Registers. The scheduler uses 48 physical registers that are
contained within the RISC86 microarchitecture when managing
the 24 RISC86 operations. The 48 physical registers are located
in a general register file and are grouped as 24 general
registers, plus 24 renaming registers. The 24 general registers
consist of 16 scratch registers and eight registers that
correspond to the x86 general purpose registers—EAX, EBX,
ECX, EDX, EBP, ESP, ESI and EDI.
Branch Logic. The AMD-K6 processor is designed with highly
sophisticated dynamic branch logic consisting of the following:
■
■
■
Branch history/Prediction table
Branch target cache
Return address stack
The AMD-K6 implements a two-level branch prediction scheme
based on an 8192-entry branch history table. The branch history
table stores prediction information that is used for predicting
conditional branches. Because the branch history table does not
Chapter 2
Internal Architecture
9
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
store predicted target addresses, special address ALUs
calculate target addresses on-the-fly during instruction decode.
Th e b ra n ch t a rg e t c a ch e a u g m e n t s p re d i c t e d b ra n ch
performance by avoiding a one clock cache-fetch penalty. This
specialized target cache does this by supplying the first 16 bytes
of target instructions to the decoders when branches are
predicted. The return address stack is a unique device
specifically designed for optimizing CALL and RETURN pairs.
In summary, the AMD-K6 uses dynamic branch logic to
minimize delays due to the branch instructions that are
common in x86 software.
AMD-K6® Processor Block Diagram. As shown in Figure 1 on page 11,
the high-performance, out-of-order execution engine of the
AMD-K6 processor is mated to a split level-one 64-Kbyte
writeback cache with 32 Kbytes of instruction cache and 32
Kbytes of data cache. The instruction cache feeds the decoders
and, in turn, the decoders feed the scheduler. The ICU issues
and retires RISC86 operations contained in the scheduler. The
system bus interface is an industry-standard 64-bit Pentium®
processor demultiplexed bus.
The AMD-K6 processor combines the latest in processor
microarchitecture to provide the highest x86 performance for
t od ay’s p e rs ona l c o m p u t e rs. The A M D -K 6 of f e rs t ru e
sixth-generation performance and full x86 binary software
compatibility.
10
Internal Architecture
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Level-One Instruction Cache
(32 KByte + Predecode)
Predecode
Logic
64-Entry ITLB
16-Byte Fetch
Level-One Cache
Controller
Socket 7
Bus
Interface
Four RISC86
Decode
Out-of-Order
Execution Engine
Scheduler
Buffer
(24 RISC86)
®
Six RISC86
Operation Issue
Load
Unit
Branch Logic
(8192-Entry BHT)
(16-Entry BTC)
(16-Entry RAS)
Dual Instruction Decoders
x86 to RISC86
Store
Unit
Integer X
(Register) Unit
Multimedia
Unit
Instruction
Control Unit
Integer Y
(Register) Unit
Floating-Point
Unit
Branch
(Resolving) Unit
Store
Queue
Level-One Dual-Port Data Cache (32 KByte)
128-Entry DTLB
Figure 1. AMD-K6® Processor Block Diagram
2.3
Cache, Instruction Prefetch, and Predecode Bits
The writeback level-one cache on the AMD-K6 processor is
organized as a separate 32-Kbyte instruction cache and a
32-Kbyte data cache with two-way set associativity. The cache
line size is 32 bytes and lines are prefetched from main memory
using an efficient pipelined burst transaction. As the
instruction cache is filled, each instruction byte is analyzed for
instruction boundaries using predecoding logic. Predecoding
annotates each instruction byte with information that later
enables the decoders to efficiently decode multiple instructions
simultaneously.
Cache
Chapter 2
The processor cache design takes advantage of a sectored
organization (see Figure 2 on page 12). Each sector consists of
64 bytes configured as two 32-byte cache lines. The two cache
lines of a sector share a common tag but have separate pairs of
MESI (Modified, Exclusive, Shared, Invalid) bits that track the
state of each cache line.
Internal Architecture
11
Preliminary Information
AMD-K6® Processor Data Sheet
Tag
Address
20695H/0—March 1998
Cache Line 1 Byte 31 Predecode Bits Byte 30 Predecode Bits ........ ........ Byte 0 Predecode Bits MESI Bits
Cache Line 2 Byte 31 Predecode Bits Byte 30 Predecode Bits ........ ........ Byte 0 Predecode Bits MESI Bits
Figure 2. Cache Sector Organization
Two forms of cache misses and associated cache fills can take
place—a sector replacement and a cache line replacement. In
the case of a sector replacement, the miss is due to a tag
mismatch, in which case the required cache line is filled from
external memory, and the cache line within the sector that was
not required is marked as invalid. In the case of a cache line
replacement, the address matches the tag, but the requested
cache line is marked as invalid. The required cache line is filled
from external memory, and the cache line within the sector that
is not required remains in the same cache state.
Prefetching
The AMD-K6 processor performs cache prefetching for sector
replacements only—as opposed to cache line replacements.
This cache prefetching results in the filling of the required
cache line first, and a prefetch of the second cache line.
Furthermore, the prefetch of the cache line that is not required
is initiated only in the forward direction—that is, only if the
requested cache line is the first cache line within the sector.
From the perspective of the external bus, the two cache-line
fills typically appear as two 32-byte burst read cycles occurring
back-to-back or, if allowed, as pipelined cycles.
Predecode Bits
Decoding x86 instructions is particularly difficult because the
instructions are variable-length and can be from 1 to 15 bytes
long. Predecode logic supplies the predecode bits that are
associated with each instruction byte. The predecode bits
indicate the number of bytes to the start of the next x86
instruction. The predecode bits are stored in an extended
instruction cache alongside each x86 instruction byte as shown
in Figure 2 on page 12. The predecode bits are passed with the
instruction bytes to the decoders where they assist with parallel
x86 instruction decoding.
12
Internal Architecture
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
2.4
Instruction Fetch and Decode
Instruction Fetch
The processor can fetch up to 16 bytes per clock out of the
instruction cache or branch target cache. The fetched
information is placed into a 16-byte instruction buffer that
feeds directly into the decoders (see Figure 3). Fetching can
occur along a single execution stream with up to seven
outstanding branches taken.
The instruction fetch logic is capable of retrieving any 16
contiguous bytes of information within a 32-byte boundary.
There is no additional penalty when the 16 bytes of instructions
lie across a cache line boundary. The instruction bytes are
loaded into the instruction buffer as they are consumed by the
decoders. Although instructions can be consumed with byte
g ra nu l a r i t y, t h e i n s t r u c t i o n b u f f e r i s m a n a g e d o n a
memory-aligned word (2 bytes) organization. Therefore,
instructions are loaded and replaced with word granularity.
When a control transfer occurs—such as a JMP instruction—
the entire instruction buffer is flushed and reloaded with a new
set of 16 instruction bytes.
16 Bytes
32-Kbyte Level-One
Instruction Cache
Branch-Target Cache
16 x 16 Bytes
16 Bytes
2:1
Branch Target
Address Adders
Return Address Stack
16 x 16 Bytes
Fetch Unit
16 Instruction Bytes
plus
16 Sets of Predecode Bits
Instruction Buffer
Figure 3. The Instruction Buffer
Chapter 2
Internal Architecture
13
Preliminary Information
AMD-K6® Processor Data Sheet
Instruction Decode
20695H/0—March 1998
The AMD-K6 processor decode logic is designed to decode
multiple x86 instructions per clock (see Figure 4). The decode
logic accepts x86 instruction bytes and their predecode bits
from the instruction buffer, locates the actual instruction
boundaries, and generates RISC86 operations from these x86
instructions.
RISC86 operations are fixed-format internal instructions. Most
RISC86 operations execute in a single clock. RISC86 operations
are combined to perform every function of the x86 instruction
set. Some x86 instructions are decoded into as few as zero
RISC86 opcodes — for instance a NOP — or one RISC86
operation — a register-to-register add. More complex x86
instructions are decoded into several RISC86 operations.
Instruction Buffer
Short Decoder #1
Short Decoder #2
Long Decoder
On-Chip ROM
Vector Decoder
RISC86® Sequencer
Vector Address
4 RISC86 Operations
Figure 4. AMD-K6® Processor Decode Logic
14
Internal Architecture
Chapter 2
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The AMD-K6 processor uses a combination of decoders to
convert x86 instructions into RISC86 operations. The hardware
consists of three sets of decoders—two parallel short decoders,
one long decoder, and one vectoring decoder. The parallel short
decoders translate the most commonly-used x86 instructions
( moves, shifts, branches, ALU, MMX, FPU) into zero, one, or
two RISC86 operations each. The short decoders only operate
on x86 instructions that are up to seven bytes long. In addition,
they are designed to decode up to two x86 instructions per
clock. The commonly-used x86 instructions that are greater
than seven bytes but not more than 11 bytes long, and
semi-commonly-used x86 instructions that are up to seven bytes
long are handled by the long decoder.
The long decoder only performs one decode per clock and
generates up to four RISC86 operations. All other translations
(complex instructions, serializing conditions, interrupts and
exceptions, etc.) are handled by a combination of the vector
decoder and RISC86 operation sequences fetched from an
on-chip ROM. For complex operations, the vector decoder logic
provides the first set of RISC86 operations and a vector (initial
ROM address) to a sequence of further RISC86 operations. The
same types of RISC86 operations are fetched from the ROM as
those that are generated by the hardware decoders.
Note: Although all three sets of decoders are simultaneously fed a
copy of the instruction buffer contents, only one of the three
types of decoders is used during any one decode clock.
The decoders or the RISC86 sequencer always generate a group
of four RISC86 operations. For decodes that cannot fill the entire
group with four RISC86 operations, RISC86 NOP operations are
placed in the empty locations of the grouping. For example, a
long-decoded x86 instruction that converts to only three RISC86
operations is padded with a single RISC86 NOP operation and
then passed to the scheduler. Up to six groups or 24 RISC86
operations can be placed in the scheduler at a time.
All of the common, and a few of the uncommon, floating-point
instructions (also known as ESC instructions) are hardware
decoded as short decodes. This decode generates a RISC86
floating-point operation and, optionally, an associated
floating-point load or store operation. Floating-point or ESC
instruction decode is only allowed in the first short decoder, but
non-ESC instructions, excluding MMX instructions, can be
Chapter 2
Internal Architecture
15
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
decoded simultaneously by the second short decoder along with
an ESC instruction decode in the first short decoder.
All of the MMX instructions, with the exception of the EMMS
instruction, are hardware decoded as short decodes. The MMX
instruction decode generates a RISC86 MMX operation and,
optionally, an associated MMX load or store operation. MMX
instruction decode is only allowed in the first short decoder.
However, instructions other than MMX and ESC instructions
can be decoded simultaneously by the second short decoder
along with an MMX instruction decode in the first short
decoder.
2.5
Centralized Scheduler
The scheduler is the heart of the AMD-K6 processor (see Figure
5 on page 17). It contains the logic necessary to manage
out-of-order execution, data forwarding, register renaming,
simultaneous issue and retirement of multiple RISC86
operations, and speculative execution. The scheduler’s buffer
can hold up to 24 RISC86 operations. This equates to a maximum
of 12 x86 instructions. When possible, the scheduler can
simultaneously issue a RISC86 operation to any available
execution unit (store, load, branch, integer, integer/multimedia,
or floating-point). In total, the scheduler can issue up to six and
retire up to four RISC86 operations per clock.
The main advantage of the scheduler and its operation buffer is
the ability to examine an x86 instruction window equal to 12
x86 instructions at one time. This advantage is due to the fact
that the scheduler operates on the RISC86 operations in
parallel and allows the AMD-K6 processor to perform dynamic
on-the-fly instruction code scheduling for optimized execution.
Although the scheduler can issue RISC86 operations for
out-of-order execution, it always retires x86 instructions in
order.
16
Internal Architecture
Chapter 2
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
From Decode Logic
RISC86 #0
RISC86 #1
RISC86 #2
Centralized RISC86®
Operation Scheduler
RISC86 #3
RISC86 Issue Buses
RISC86 Operation Buffer
Figure 5. AMD-K6® Processor Scheduler
2.6
Execution Units
The AMD-K6 processor contains seven execution units—store,
load, integer X, integer Y, multimedia, floating-point, and
branch condition. Each unit is independent and capable of
handling the RISC86 operations. Table 1 on page 18 details the
execution units, functions performed within these units,
operation latency, and operation throughput.
The store and load execution units are two-staged pipelined
designs. The store unit performs data writes and register
calculation for LEA/PUSH. Data memory and register writes
from stores are available after one clock. The load unit
performs data memory reads. Data is available from the load
unit after two clocks.
The I nte ger X executio n unit can operat e on a ll AL U
operations, multiplies, divides (signed and unsigned), shifts,
and rotates.
Chapter 2
Internal Architecture
17
Preliminary Information
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The multimedia unit shares pipeline control with the Integer X
unit and executes all MMX instructions.
The Integer Y execution unit can operate on the basic word and
doubleword ALU operations — ADD, AND, CMP, OR, SUB,
XOR, zero-extend and sign-extend operands.
The branch condition unit is separate from the branch
prediction logic in that it resolves conditional branches such as
JCC and LOOP after the branch condition has been evaluated.
Table 1.
Execution Latency and Throughput of Execution Units
Execution Unit
Store
Load
Integer X
Multimedia
Function
LEA/PUSH, Address
1
1
Memory Store
1
1
Memory Loads
2
1
Integer ALU
1
1
2–3
2–3
Integer Shift
1
1
MMX ALU
1
1
MMX Shifts, Packs, Unpack
1
1
1–2
1–2
Integer Multiply
MMX Multiply
18
Latency Throughput
Integer Y
Basic ALU (16- & 32-bit operands)
1
1
Branch
Resolves Branch Conditions
1
1
FPU
FADD, FSUB, FMUL
2
2
Internal Architecture
Chapter 2
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
2.7
Branch-Prediction Logic
Sophisticated branch logic that can minimize or hide the impact
of changes in program flow is designed into the AMD-K6
processor. Branches in x86 code fit into two categories —
unconditional branches, which always change program flow (that
is, the branches are always taken) and conditional branches,
which may or may not divert program flow (that is, the branches
are taken or not-taken). When a conditional branch is not taken,
the processor simply continues decoding and executing the next
instructions in memory.
Typical applications have up to 10% of unconditional branches
and another 10% to 20% conditional branches. The AMD-K6
branch logic has been designed to handle this type of program
behavior and its negative effects on instruction execution, such
as stalls due to delayed instruction fetching and the draining of
the processor pipeline. The branch logic contains an 8192-entry
branch history table, a 16-entry by 16-byte branch target cache,
a 16-entry return address stack, and a branch execution unit.
Branch History Table
The AMD-K6 processor handles unconditional branches
without any penalty by redirecting instruction fetching to the
target address of the unconditional branch. However,
c o n d i t i o n a l b ra n che s re q u i re t h e u se o f t h e dy n a m i c
branch-prediction mechanism built into the AMD-K6. A
two-level adaptive history algorithm is implemented in an
8192-entry branch history table. This table stores executed
branch information, predicts individual branches, and predicts
the behavior of groups of branches. To accommodate the large
branch history table, the AMD-K6 processor does not store
predicted target addresses. Instead, the branch target
addresses are calculated on-the-fly using ALUs during the
decode stage. The adders calculate all possible target addresses
before the instructions are fully decoded and the processor
chooses which addresses are valid.
Branch Target Cache
To avoid a one clock cache-fetch penalty when a branch is
predicted taken, a built-in branch target cache supplies the first
16 bytes of instructions directly to the instruction buffer
(assuming the target address hits this cache). (See Figure 3 on
page 13.) The branch target cache is organized as 16 entries of
16 bytes. In total, the branch prediction logic achieves branch
prediction rates greater than 95%.
Chapter 2
Internal Architecture
19
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Return Address Stack
The return address stack is a special device designed to
optimize CALL and RET pairs. Software is typically compiled
with subroutines that are frequently called from various places
in a program. This is usually done to save space. Entry into the
subroutine occurs with the execution of a CALL instruction. At
that time, the processor pushes the address of the next
instruction in memory following the CALL instruction onto the
stack (allocated space in memory). When the processor
encounters a RET instruction (within or at the end of the
subroutine), the branch logic pops the address from the stack
and begins fetching from that location. To avoid the latency of
main memory accesses during CALL and RET operations, the
return address stack caches the pushed addresses.
Branch Execution
Unit
The branch execution unit enables efficient speculative
execution. This unit gives the processor the ability to execute
instructions beyond conditional branches before knowing
whether the branch prediction was correct. The AMD-K6
processor does not permanently update the x86 registers or
memory locations until all speculatively executed conditional
branch instructions are resolved. When a prediction is
incorrect, the processor backs out to the point of the
mispredicted branch instruction and restores all registers. The
AMD-K6 can support up to seven outstanding branches.
20
Internal Architecture
Chapter 2
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
3
Software Environment
This chapter provides a general overview of the AMD-K6
processor’s x86 software environment and briefly describes the
data types, registers, operating modes, interrupts, and
instructions supported by the AMD-K6 architecture and design
implementation.
3.1
Registers
The AMD-K6 processor contains all the registers defined by the
x86 architecture, including general-purpose, segment,
floating-point, MMX, EFLAGS, control, task, debug, test, and
descriptor/memory-management registers. In addition, this
chapter provides information on the AMD-K6 Model-Specific
Registers (MSRs).
Note: Areas of the register designated as Reserved should not be
modified by software.
General-Purpose
Registers
The eight 32-bit x86 general-purpose registers are used to hold
integer data or memory pointers used by instructions. Table 2
contains a list of the general-purpose registers and the
functions for which they are used.
Table 2.
Register
General-Purpose Registers
Function
EAX
Commonly used as an accumulator
EBX
Commonly used as a pointer
ECX
Commonly used for counting in loop operations
EDX
Commonly used to hold I/O information and to pass parameters
EDI
Commonly used as a destination pointer by the ES segment
ESI
Commonly used as a source pointer by the DS segment
ESP
Used to point to the stack segment
EBP
Used to point to data within the stack segment
In order to support byte and word operations, EAX, EBX, ECX,
and EDX can also be used as 8-bit and 16-bit registers. The
shorter registers are overlaid on the longer ones. For example,
the name of the 16-bit version of EAX is AX (low 16 bits of
EAX) and the 8-bit names for AX are AH (high order bits) and
Chapter 3
Software Environment
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
AL (low order bits). The same naming convention applies to
EBX, ECX, and EDX. EDI, ESI, ESP, and EBP can be used as
smaller 16-bit registers called DI, SI, SP, and BP respectively,
but these registers do not have 8-bit versions. Figure 6 shows the
EAX register with its name components, and Table 3 lists the
dwo rd ( 3 2 b i t s ) g e n e ra l -p u rp o s e re g i s t e rs a n d t h e i r
corresponding word (16 bits) and byte (8 bits) versions.
31
16 15
8
7
0
EAX
AX
AL
AH
Figure 6. EAX Register with 16-Bit and 8-Bit Name Components
Table 3.
22
General-Purpose Register Dword, Word, and Byte Names
32-Bit Name
(Dword)
16-Bit Name
(Word)
EAX
AX
AH
AL
EBX
BX
BH
BL
ECX
CX
CH
CL
EDX
DX
DH
DL
EDI
DI
–
–
ESI
SI
–
–
ESP
SP
–
–
EBP
BP
–
–
Software Environment
8-Bit Name
8-Bit Name
(High-order Bits) (Low-order Bits)
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Integer Data Types
Four types of data are used in general-purpose registers—byte,
word, doubleword, and quadword integers. Figure 7 shows the
format of the integer data registers.
Byte Integer
7
0
Precision —
8 Bits
Word Integer
15
0
Precision — 16 Bits
Doubleword Integer
31
0
Precision — 32 Bits
Quadword Integer
63
0
Precision — 64 Bits
Figure 7. Integer Data Types
Chapter 3
Software Environment
23
Preliminary Information
AMD-K6® Processor Data Sheet
Segment Registers
20695H/0—March 1998
The six 16-bit segment registers are used as pointers to areas
(segments) of memory. Table 4 lists the segment registers and
their functions. Figure 8 shows the format for all six segment
registers.
Table 4.
Segment
Register
Segment Registers
Segment Register Function
CS
Code segment, where instructions are located
DS
Data segment, where data is located
ES
Data segment, where data is located
FS
Data segment, where data is located
GS
Data segment, where data is located
SS
Stack segment
15
0
Figure 8. Segment Register
Segment Usage
24
The operating system determines the type of memory model
that is implemented. The segment register usage is determined
by the operating system’s memory model. In a Real mode
memory model the segment register points to the base address
in memory. In a Protected mode memory model the segment
register is called a selector and it selects a segment descriptor
in a descriptor table. This descriptor contains a pointer to the
base of the segment, the limit of the segment, and various
protection attributes. For more information on descriptor
formats, see “Descriptors and Gates” on page 45. Figure 9 on
page 25 shows segment usage for Real mode and Protected
mode memory models.
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Physical Memory
Segment Base
Segment Register
Real Mode Memory Model
Descriptor Table
Physical Memory
Base
Limit
Base
Base
Limit
Segment Base
Segment Selector
Protected Mode Memory Model
Figure 9. Segment Usage
Instruction Pointer
The instruction pointer (EIP or IP) is used in conjunction with
the code segment register (CS). The instruction pointer is
either a 32-bit register (EIP) or a 16-bit register (IP) that keeps
track of where the next instruction resides within memory. This
register cannot be directly manipulated, but can be altered by
modifying return pointers when a JMP or CALL instruction is
used.
Floating-Point
Registers
The floating-point execution unit in the AMD-K6 processor is
designed to perform mathematical operations on non-integer
numbers. This floating-point unit conforms to the IEEE 754 and
854 standards and uses several registers to meet these
standards — eight numeric floating-point registers, a status
word register, a control word register, and a tag word register.
Chapter 3
Software Environment
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The eight floating-point registers are 80 bits wide and labeled
FPR0–FPR7. Figure 10 shows the format of these floating-point
registers. See “Floating-Point Register Data Types” on page 28
for information on allowable floating-point data types.
79 78
64 63
Sign
0
Exponent
Significand
Figure 10. Floating-Point Register
The 16-bit FPU status word register contains information about
the state of the floating-point unit. Figure 11 shows the format
of this register.
15 14 13 12 11 10 9 8
B
Symbol
B
C3
TOSP
C2
C1
C0
ES
SF
PE
UE
OE
ZE
DE
IE
C
3
TOSP
C
2
C C
1 0
7
6
5
4
3
2
1
0
E
S
S
F
P U O Z
E E E E
D
E
I
E
Description
Bits
FPU Busy
15
Condition Code
14
Top of Stack Pointer
13–11
Condition Code
10
Condition Code
9
Condition Code
8
Error Summary Status
7
Stack Fault
6
Exception Flags
Precision Error
5
Underflow Error
4
Overflow Error
3
Zero Divide Error
2
Denormalized Operation Error 1
Invalid Operation Error
0
TOSP Information
000 = FPR0
111 = FPR7
Figure 11. FPU Status Word Register
26
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The FPU control word register allows a programmer to manage
the FPU processing options. Figure 12 shows the format of this
register.
15 14 13 12 11 10 9 8
Y
R
C
7
P
C
6
5
4
3
2
1
0
P U O Z D I
M M M M M M
Reserved
Symbol
Y
RC
PC
PM
UM
OM
ZM
DM
IM
Description
Infinity Bit (80287 compatibility)
Rounding Control
Precision Control
Exception Masks
Precision
Underflow
Overflow
Zero Divide
Denormalized Operation
Invalid Operation
Bits
12
11–10
9–8
5
4
3
2
1
0
Rounding Control Information
00b = Round to the nearest or even number
01b = Round down toward negative infinity
10b = Round up toward positive infinity
11b = Truncate toward zero
Precision Control Information
00b = 24 bits Single Precision Real
01b = Reserved
10b = 53 bits Double Precision Real
11b = 64 bits Extended Precision Real
Figure 12. FPU Control Word Register
The FPU tag word register contains information about the
registers in the register stack. Figure 13 shows the format of this
register.
15 14 13 12 11 10 9 8
7
6
5
4
3
2
1
0
TAG
TAG
TAG
TAG
TAG
TAG
TAG
TAG
(FPR7 (FPR6 (FPR5 (FPR4 (FPR3 (FPR2 (FPR1 (FPR0
Tag Values
00 = Valid
01 = Zero
10 = Special
11 = Empty
Figure 13. FPU Tag Word Register
Chapter 3
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27
Preliminary Information
AMD-K6® Processor Data Sheet
Floating-Point
Register Data Types
79 78
S
20695H/0—March 1998
Floating-point registers use four different types of data —
packed decimal, single precision real, double precision real,
and extended precision real. Figures 14 and 15 show the
formats for these registers.
72 71
0
Ignore
or
Zero
Precision — 18 Digits, 72 Bits Used, 4-Bits/Digit
Description
Bits
Ignored on Load, Zeros on Store 78-72
Sign Bit
79
Figure 14. Packed Decimal Data Type
31 30
Single Precision Real
S
23 22
0
Biased
Exponent
Significand
S = Sign Bit
Double Precision Real
52 51
63 62
S
0
Biased
Exponent
Significand
S = Sign Bit
Extended Precision Real
79 78
S
64 63 62
Biased
Exponent
S = Sign Bit
0
I
Significand
I = Integer Bit
Figure 15. Precision Real Data Types
28
Software Environment
Chapter 3
Preliminary Information
20695H/0—March 1998
AMD-K6® Processor Data Sheet
MMX™ Registers
The AMD-K6 processor implements eight 64-bit MMX registers
and three packed data types for use by multimedia software.
These registers are mapped on the floating-point registers. The
MMX instructions refer to these registers as mm0 to mm7.
Figures 16 and 17 show the format of these registers and data
types. See AMD-K6® Processor Multimedia Technology, order#
20726 for more information.
63
0
mm0
mm1
mm2
mm3
mm4
mm5
mm6
mm7
Figure 16. MMX™ Registers
Chapter 3
Software Environment
29
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Packed Bytes
63
56 55
48 47
40
39
32
31
24
23
16
15
8
7
0
Packed Words
63
48 47
32 31
16 15
0
Packed Doublewords
63
32
31
0
Figure 17. MMX™ Data Types
30
Software Environment
Chapter 3
Preliminary Information
20695H/0—March 1998
AMD-K6® Processor Data Sheet
EFLAGS Register
The EFLAGS register provides for three different types of
flags — system, control, and status. The system flags provide
operating system controls, the control flag provides directional
information for string operations, and the status flags provide
information resulting from logical and arithmetic operations.
Figure 18 shows the format of this register.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
V
I I
D P
V
I
F
A V R
C M F
N
T
I
O
P
L
O D
F F
I
F
8
7
6
T
F
S
F
Z
F
5
4
A
F
3
2
P
F
1
0
C
F
Reserved
Symbol
ID
VIP
VIF
AC
VM
RF
NT
IOPL
OF
DF
IF
TF
SF
ZF
AF
PF
CF
Description
Bits
ID Flag
21
Virtual Interrupt Pending
20
Virtual Interrupt Flag
19
Alignment Check
18
Virtual-8086 Mode
17
Resume Flag
16
Nested Task
14
I/O Privilege Level
13–12
Overflow Flag
11
Direction Flag
10
Interrupt Flag
9
Trap Flag
8
Sign Flag
7
Zero Flag
6
Auxiliary Flag
4
Parity Flag
2
Carry Flag
0
Figure 18. EFLAGS Registers
Chapter 3
Software Environment
31
Preliminary Information
AMD-K6® Processor Data Sheet
Control Registers
20695H/0—March 1998
The five control registers contain system control bits and
pointers. Figures 19 through 23 show the formats of these
registers.
31
7
6
5
M
C
E
4
3
2
1
0
P
S
E
T
D S
E D
P V
V M
I E
4
3
1
Reserved
Symbol
MCE
PSE
DE
TSD
PVI
VME
Description
Machine Check Enable
Page Size Extensions
Debugging Extensions
Time Stamp Disable
Protected Virtual Interrupts
Virtual-8086 Mode Extensions
Bit
6
4
3
2
1
0
Figure 19. Control Register 4 (CR4)
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Page Directory Base
8
7
6
5
2
0
P P
C W
D T
Reserved
Symbol
PCD
PWT
Description
Page Cache Disable
Page Writethrough
Bit
4
3
Figure 20. Control Register 3 (CR3)
31
0
Page Fault Linear Address
Figure 21. Control Register 2 (CR2)
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Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
31
0
Reserved
Figure 22. Control Register 1 (CR1)
Symbol
PG
CD
NW
Description
Paging
Cache Disable
Not Writethrough
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
P C N
G D W
A
M
W
P
Bit
31
30
29
8
7
6
5
4
3
2
1
0
N
E
E T E M P
T S M P E
Reserved
Symbol
AM
WP
NE
ET
TS
EM
MP
PE
Description
Alignment Mask
Write Protect
Numeric Error
Extension Type
Task Switched
Emulation
Monitor Co-processor
Protection Enabled
Bit
18
16
5
4
3
2
1
0
Figure 23. Control Register 0 (CR0)
Chapter 3
Software Environment
33
Preliminary Information
AMD-K6® Processor Data Sheet
Debug Registers
20695H/0—March 1998
Figures 24 through 27 show the 32-bit debug registers
supported by the processor.
Symbol
LEN 3
R/W 3
LEN 2
R/W 2
LEN 1
R/W 1
LEN 0
R/W 0
Description
Length of Breakpoint #3
Type of Transaction(s) to Trap
Length of Breakpoint #2
Type of Transaction(s) to Trap
Length of Breakpoint #1
Type of Transaction(s) to Trap
Length of Breakpoint #0
Type of Transaction(s) to Trap
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
LEN
3
R/W
3
LEN
2
R/W
2
LEN
1
R/W
1
LEN
0
R/W
0
G
D
G
E
8
7
Bits
31–30
29–28
27–26
25–24
23–22
21–20
19–18
17–16
6
5
4
3
L G L
E 3 3
L
2
L G
2 1
2
1
0
L G
1 0
L
0
Reserved
Symbol
GD
GE
LE
G3
L3
G2
L2
G1
L1
G0
L0
Description
General Detect Enabled
Global Exact Breakpoint Enabled
Local Exact Breakpoint Enabled
Global Exact Breakpoint # 3 Enabled
Local Exact Breakpoint # 3 Enabled
Global Exact Breakpoint # 2 Enabled
Local Exact Breakpoint # 2 Enabled
Global Exact Breakpoint # 1 Enabled
Local Exact Breakpoint # 1 Enabled
Global Exact Breakpoint # 0 Enabled
Local Exact Breakpoint # 0 Enabled
Bit
13
9
8
7
6
5
4
3
2
1
0
Figure 24. Debug Register DR7
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Software Environment
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
B B B
T S D
3
2
1
0
B
3
B
2
B
1
B
0
Reserved
Symbol
BT
BS
BD
B3
B2
B1
B0
Description
Breakpoint Task Switch
Breakpoint Single Step
Breakpoint Debug Access Detected
Breakpoint #3 Condition Detected
Breakpoint #2 Condition Detected
Breakpoint #1 Condition Detected
Breakpoint #0 Condition Detected
Bit
15
14
13
3
2
1
0
Figure 25. Debug Register DR6
DR5
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
Reserved
DR4
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Reserved
Figure 26. Debug Registers DR5 and DR4
Chapter 3
Software Environment
35
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
DR3
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
8
7
6
4
3
2
1
0
8
7
6
4
3
2
1
0
Breakpoint 3 32-bit Linear Address
DR2
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Breakpoint 2 32-bit Linear Address
DR1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
5
Breakpoint 1 32-bit Linear Address
DR0
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
5
Breakpoint 0 32-bit Linear Address
Figure 27. Debug Registers DR3, DR2, DR1, and DR0
36
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Model-Specific
Registers (MSR)
The AMD-K6 processor provides five MSRs. The value in the
ECX register selects the MSR to be addressed by the RDMSR
and WRMSR instructions. The values in EAX and EDX are used
as inputs and outputs by the RDMSR and WRMSR instructions.
Table 5 lists the MSRs and the corresponding value of the ECX
register. Figures 28 through 32 show the MSR formats.
Table 5.
Model-Specific Registers (MSRs)
Model-Specific Register
Value of ECX
Machine Check Address Register (MCAR)
00h
Machine Check Type Register (MCTR)
01h
Test Register 12 (TR12)
0Eh
Time Stamp Counter (TSC)
10h
Write Handling Control Register (WHCR)
C000_0082h
For mo re info rma tio n abo ut the RD MSR and WRMSR
instructions, see the AMD K86™ Family BIOS and Software Tools
Development Guide, order# 21062.
MCAR and MCTR. The AMD-K6 processor does not support the
generation of a machine check exception. However, the
processor does provide a 64-bit Machine Check Address
Register (MCAR), a 64-bit Machine Check Type Register
(MCTR), and a Machine Check Enable (MCE) bit in CR4.
Because the processor does not support machine check
exceptions, the contents of the MCAR and MCTR are only
affected by the WRMSR instruction and by RESET being
sampled asserted (where all bits in each register are reset to 0).
63
0
MCAR
Figure 28. Machine-Check Address Register (MCAR)
Chapter 3
Software Environment
37
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
63
5
4
0
MCTR
Reserved
Figure 29. Machine-Check Type Register (MCTR)
Test Register 12 (TR12). Test register 12 provides a method for
disabling the L1 caches. Figure 30 shows the format of TR12.
63
4 3
2
1
0
C
I
Reserved
Symbol Description
CI
Cache Inhibit Bit
Bit
3
Figure 30. Test Register 12 (TR12)
Time Stamp Counter. Wi t h e a ch p ro c e s s o r c l o ck cy c l e , t h e
processor increments the 64-bit time stamp counter (TSC) MSR.
Figure 31 shows the format of the TSC.
63
0
TSC
Figure 31. Time Stamp Counter (TSC)
38
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Write Handling Control Register (WHCR). The Write Handling Control
Register (WHCR) is a MSR that contains three fields — the
WCDE bit, Write Allocate Enable Limit (WAELIM) field, and
the Write Allocate Enable 15-to-16-Mbyte (WAE15M) bit.
Figure 32 shows the format of WHCR. See “Write Allocate” on
page 177 for more information.
9
63
8
0
7
1
WAELIM
0
W
A
E
1
5
M
Reserved
Symbol
WCDE
WAELIM
WAE15M
Description
Bits
Always program to 0
8
Write Allocate Enable Limit
7–1
Write Allocate Enable 15-to-16-Mbyte 0
Note: Hardware RESET initializes this MSR to all zeros.
Figure 32. Write Handling Control Register (WHCR)
Memory
Management
Registers
Table 6.
Th e A M D -K 6 p ro c e s s o r c o n t ro l s s e g m e n t e d m e m o ry
management with the registers listed in Table 6. Figure 33 on
page 40 shows the formats of these registers.
Memory Management Registers
Register Name
Function
Global Descriptor Table Register
Contains a pointer to the base of the Global Descriptor Table
Interrupt Descriptor Table Register
Contains a pointer to the base of the Interrupt Descriptor Table
Local Descriptor Table Register
Contains a pointer to the Local Descriptor Table of the current task
Task Register
Contains a pointer to the Task State Segment of the current task
Chapter 3
Software Environment
39
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Global and Interrupt Descriptor Table Registers
16 15
47
32-Bit Linear Base Address
Local Descriptor Table Register and Task Register
0
16-Bit Limit
15
0
Selector
63
0
32 31
32-Bit Linear Base Address
32-Bit Limit
15
0
Attributes
Figure 33. Memory Management Registers
40
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Task State Segment
Figure 34 shows the format of the Task State Segment (TSS).
31
0
TSS Limit
from TR
I/O Permission Bitmap (IOPB)
(up to 8 Kbytes)
Interrupt Redirection Bitmap (IRB)
(eight 32-bit locations)
Operating System
Data Structure
Base Address of IOPB
0000h
0000h
LDT Selector
0000h
GS
T
64h
FS
0000h
0000h
0000h
DS
SS
0000h
CS
ES
0000h
EDI
ESI
EBP
ESP
EBX
EDX
ECX
EAX
EFLAGS
EIP
CR3
SS2
0000h
ESP2
0000h
SS1
ESP1
0000h
SS0
ESP0
0000h
Link (Prior TSS Selector)
0
Figure 34. Task State Segment (TSS)
Chapter 3
Software Environment
41
Preliminary Information
AMD-K6® Processor Data Sheet
Paging
20695H/0—March 1998
The AMD-K6 processor can address up to 4 Gbytes of memory.
This memory can be segmented into pages. The size of these
pages is determined by the operating system design and the
values set up in the Page Directory Entries (PDE) and Page
Table Entries (PTE). The processor can access both 4-Kbyte
pages and 4-Mbyte pages, and the page sizes can be intermixed
within a page directory. When the Page Size Extension (PSE)
bit in CR4 is set, the processor translates linear addresses using
either the 4-Kbyte Translation Lookaside Buffer (TLB) or the
4-Mbyte TLB, depending on the state of the page size (PS) bit in
the page directory entry. Figures 35 and 36 show how 4-Kbyte
and 4-Mbyte page translations work.
Page
Directory
4-Kbyte
Page
Frame
Page
Table
PTE
Physical
Address
PDE
CR3
31
22 21
Page Directory
Offset
12 11
Page Table
Offset
0
Page
Offset
Linear Address
Figure 35. 4-Kbyte Paging Mechanism
42
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
4-Mbyte
Page
Frame
Page
Directory
Physical
Address
PDE
CR3
31
22 21
0
Page Directory
Offset
Page
Offset
Linear Address
Figure 36. 4-Mbyte Paging Mechanism
Figures 37 through 39 show the formats of the PDE and PTE.
These entries contain information regarding the location of
pages and their status.
Chapter 3
Software Environment
43
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
31
12 11 10 9 8
A
V
L
Page Table Base Address
Symbol
AVL
PS
A
PCD
PWT
U/S
W/R
P
Description
Available to Software
Reserved
Page Size
Reserved
Accessed
Page Cache Disable
Page Writethrough
User/Supervisor
Write/Read
Present (valid)
7
6
0
5
4
3
2
1
0
A
P P U W
C W / / P
D T S R
5
4
A
P P U W
C W / / P
D T S R
Bits
11–9
8
7
6
5
4
3
2
1
0
Figure 37. Page Directory Entry 4-Kbyte Page Table (PDE)
31
22 21
12 11 10 9 8
Physical Page Base Address
Symbol
AVL
PS
A
PCD
PWT
U/S
W/R
P
Description
Available to Software
Reserved
Page Size
Reserved
Accessed
Page Cache Disable
Page Writethrough
User/Supervisor
Write/Read
Present (valid)
Reserved
A
V
L
7
1
6
3
2
1
0
Bits
11–9
8
7
6
5
4
3
2
1
0
Figure 38. Page Directory Entry 4-Mbyte Page Table (PDE)
44
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
31
12 11 10 9 8
Physical Page Base Address
Symbol
AVL
D
A
PCD
PWT
U/S
W/R
P
Description
Available to Software
Reserved
Dirty
Accessed
Page Cache Disable
Page Writethrough
User/Supervisor
Write/Read
Present (valid)
A
V
L
7
6
5
D A
4
3
2
1
0
P P U W
C W / / P
D T S R
Bits
11–9
8–7
6
5
4
3
2
1
0
Figure 39. Page Table Entry (PTE)
Descriptors and Gates
There are various types of structures and registers in the x86
architecture that define, protect, and isolate code segments,
data segments, task state segments, and gates. These structures
are called descriptors.
Figure 40 on page 46 shows the application segment descriptor
format. Table 7 contains information describing the memory
segment type to which the descriptor points. The application
segment descriptor is used to point to either a data or code
segment.
Figure 41 on page 47 shows the system segment descriptor
format. Table 8 contains information describing the type of
segment or gate to which the descriptor points. The system
segment descriptor is used to point to a task state segment, a
call gate, or a local descriptor table.
The AMD-K6 processor uses gates to transfer control between
executable segments with different privilege levels. Figure 42
on page 48 shows the format of the gate descriptor types. Table
8 contains information describing the type of segment or gate
to which the descriptor points.
Chapter 3
Software Environment
45
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Symbol
G
D
AVL
P
DPL
DT
Type
Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Base Address 31–24
G D
A
V
L
Segment
Limit
P
DPL
1
Base Address 15–0
8
7
Description
Granularity
32-Bit/16-Bit
Available to Software
Present/Valid Bit
Descriptor Privilege Level
Descriptor Type
See Table 7
6
Type
5
4
3
2
1
Bits
23
22
20
15
14-13
12
11-8
0
Base Address 23–16
Segment Limit 15–0
Figure 40. Application Segment Descriptor
Table 7.
Application Segment Types
Type Data/Code
0
Read-Only
1
Read-Only—Accessed
2
Read/Write
3
4
Data
Read/Write—Accessed
Read-Only—Expand-down
5
Read-Only—Expand-down, Accessed
6
Read/Write—Expand-down
7
Read/Write—Expand-down, Accessed
8
Execute-Only
9
Execute-Only—Accessed
A
Execute/Read
B
C
46
Description
Code
Execute/Read—Accessed
Execute-Only—Conforming
D
Execute-Only—Conforming, Accessed
E
Execute/Read-Only—Conforming
F
Execute/Read-Only—Conforming, Accessed
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Symbol
G
X
AVL
P
DPL
DT
Type
Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Base Address 31–24
A
V
L
G X
Segment
Limit
P
DPL
0
Base Address 15–0
8
7
Description
Granularity
Not Needed
Availability to Software
Present/Valid Bit
Descriptor Privilege Level
Descriptor Type
See Table 8
6
Type
5
4
3
2
1
Bits
23
22
20
15
14-13
12
11-8
0
Base Address 23–16
Segment Limit 15–0
Figure 41. System Segment Descriptor
Table 8.
Type
Chapter 3
System Segment and Gate Types
Description
0
Reserved
1
Available 16-bit TSS
2
LDT
3
Busy 16-bit TSS
4
16-bit Call Gate
5
Task Gate
6
16-bit Interrupt Gate
7
16-bit Trap Gate
8
Reserved
9
Available 32-bit TSS
A
Reserved
B
Busy 32-bit TSS
C
32-bit Call Gate
D
Reserved
E
32-bit Interrupt Gate
F
32-bit Trap Gate
Software Environment
47
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Symbol
P
DPL
DT
Type
Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Offset 31–16
P
DPL
0
8
7
6
5
Description
Present/Valid Bit
Descriptor Privilege Level
Descriptor Type
See Table 8
4
3
2
1
Bits
15
14-13
12
11-8
0
Type
Segment Selector
Offset 15–0
Figure 42. Gate Descriptor
Exceptions and
Interrupts
Table 9.
Interrupt
Number
48
Table 9 summarizes the exceptions and interrupts.
Summary of Exceptions and Interrupts
Interrupt Type
Cause
0
Divide by Zero Error
DIV, IDIV
1
Debug
Debug trap or fault
2
Non-Maskable Interrupt NMI signal sampled asserted
3
Breakpoint
Int 3
4
Overflow
INTO
5
Bounds Check
BOUND
6
Invalid Opcode
Invalid instruction
7
Device Not Available
ESC and WAIT
8
Double Fault
Fault occurs while handling a fault
9
Reserved - Interrupt 13
—
10
Invalid TSS
Task switch to an invalid segment
11
Segment Not Present
Instruction loads a segment and present bit is 0 (invalid segment)
12
Stack Segment
Stack operation causes limit violation or present bit is 0
13
General Protection
Segment related or miscellaneous invalid actions
14
Page Fault
Page protection violation or a reference to missing page
16
Floating-Point Error
Arithmetic error generated by floating-point instruction
17
Alignment Check
Data reference to an unaligned operand. (The AC flag and the AM bit of CR0 are
set to 1.)
0-255
Software Interrupt
INT n
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
3.2
Instructions Supported by the AMD-K6® Processor
This section documents all of the x86 instructions supported by
the AMD-K6 processor. The following tables show the
instruction mnemonic, opcode, modR/M byte, decode type, and
RISC86 operation(s) for each instruction. Tables 10 through 12
define the integer, floating-point, and MMX instructions,
respectively.
The first column in these tables indicates the instruction
mnemonic and operand types with the following notations:
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Chapter 3
reg8—byte integer register defined by instruction byte(s) or
bits 5, 4, and 3 of the modR/M byte
mreg8—byte integer register defined by bits 2, 1, and 0 of
the modR/M byte
reg16/32—word and doubleword integer register defined by
instruction byte(s) or bits 5, 4, and 3 of the modR/M byte
mreg16/32—word and doubleword integer register defined
by bits 2, 1, and 0 of the modR/M byte
mem8—byte integer value in memory
mem16/32—word or doubleword integer value in memory
mem32/48—doubleword or 48-bit integer value in memory
mem48—48-bit integer value in memory
mem64—64-bit value in memory
imm8—8-bit immediate value
imm16/32—16-bit or 32-bit immediate value
disp8—8-bit displacement value
disp16/32—16-bit or 32-bit displacement value
disp32/48—doubleword or 48-bit displacement value
eXX—register width depending on the operand size
mem32real—32-bit floating-point value in memory
mem64real—64-bit floating-point value in memory
mem80real—80-bit floating-point value in memory
mmreg—MMX register
mmreg1—MMX register defined by bits 5, 4, and 3 of the
modR/M byte
mmreg2—MMX register defined by bits 2, 1, and 0 of the
modR/M byte
Software Environment
49
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The second and third columns list all applicable opcode bytes.
The fourth column lists the modR/M byte when used by the
instruction. The modR/M byte defines the instruction as a
register or memory form. If modR/M bits 7 and 6 are documented
as mm (memory form), mm can only be 10b, 01b or 00b.
The fifth column lists the type of instruction decode — short,
long, and vector. The AMD-K6 decode logic can process two
short, one long, or one vector decode per clock.
The sixth column lists the type of RISC86 operation(s) required
for the instruction. The operation types and corresponding
execution units are as follows:
■
■
■
■
■
■
■
■
load, fload, mload—load unit
store, fstore, mstore—store unit
alu—either of the integer execution units
alux—integer X execution unit only
branch—branch condition unit
float—floating-point execution unit
meu—multimedia execution unit for MMX software
limm—load immediate, instruction control unit
Table 10. Integer Instructions
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RISC86®
Opcodes
Decode
Type
AAA
37h
AAD
D5h
0Ah
vector
AAM
D4h
0Ah
vector
AAS
3Fh
ADC mreg8, reg8
10h
11-xxx-xxx
short
alux
ADC mem8, reg8
10h
mm-xxx-xxx
long
load, alux, store
ADC mreg16/32, reg16/32
11h
11-xxx-xxx
short
alu
ADC mem16/32, reg16/32
11h
mm-xxx-xxx
long
load, alu, store
ADC reg8, mreg8
12h
11-xxx-xxx
short
alux
ADC reg8, mem8
12h
mm-xxx-xxx
short
load, alux
ADC reg16/32, mreg16/32
13h
11-xxx-xxx
short
alu
ADC reg16/32, mem16/32
13h
mm-xxx-xxx
short
load, alu
ADC AL, imm8
14h
xx-xxx-xxx
short
alux
50
vector
vector
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
ADC EAX, imm16/32
15h
xx-xxx-xxx
short
alu
ADC mreg8, imm8
80h
11-010-xxx
short
alux
ADC mem8, imm8
80h
mm-010-xxx
long
load, alux, store
ADC mreg16/32, imm16/32
81h
11-010-xxx
short
alu
ADC mem16/32, imm16/32
81h
mm-010-xxx
long
load, alu, store
ADC mreg16/32, imm8 (signed ext.)
83h
11-010-xxx
short
alux
ADC mem16/32, imm8 (signed ext.)
83h
mm-010-xxx
long
load, alux, store
ADD mreg8, reg8
00h
11-xxx-xxx
short
alux
ADD mem8, reg8
00h
mm-xxx-xxx
long
load, alux, store
ADD mreg16/32, reg16/32
01h
11-xxx-xxx
short
alu
ADD mem16/32, reg16/32
01h
mm-xxx-xxx
long
load, alu, store
ADD reg8, mreg8
02h
11-xxx-xxx
short
alux
ADD reg8, mem8
02h
mm-xxx-xxx
short
load, alux
ADD reg16/32, mreg16/32
03h
11-xxx-xxx
short
alu
ADD reg16/32, mem16/32
03h
mm-xxx-xxx
short
load, alu
ADD AL, imm8
04h
xx-xxx-xxx
short
alux
ADD EAX, imm16/32
05h
xx-xxx-xxx
short
alu
ADD mreg8, imm8
80h
11-000-xxx
short
alux
ADD mem8, imm8
80h
mm-000-xxx
long
load, alux, store
ADD mreg16/32, imm16/32
81h
11-000-xxx
short
alu
ADD mem16/32, imm16/32
81h
mm-000-xxx
long
load, alu, store
ADD mreg16/32, imm8 (signed ext.)
83h
11-000-xxx
short
alux
ADD mem16/32, imm8 (signed ext.)
83h
mm-000-xxx
long
load, alux, store
AND mreg8, reg8
20h
11-xxx-xxx
short
alux
AND mem8, reg8
20h
mm-xxx-xxx
long
load, alux, store
AND mreg16/32, reg16/32
21h
11-xxx-xxx
short
alu
AND mem16/32, reg16/32
21h
mm-xxx-xxx
long
load, alu, store
AND reg8, mreg8
22h
11-xxx-xxx
short
alux
AND reg8, mem8
22h
mm-xxx-xxx
short
load, alux
AND reg16/32, mreg16/32
23h
11-xxx-xxx
short
alu
AND reg16/32, mem16/32
23h
mm-xxx-xxx
short
load, alu
AND AL, imm8
24h
xx-xxx-xxx
short
alux
AND EAX, imm16/32
25h
xx-xxx-xxx
short
alu
Chapter 3
Software Environment
51
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
AND mreg8, imm8
80h
11-100-xxx
short
alux
AND mem8, imm8
80h
mm-100-xxx
long
load, alux, store
AND mreg16/32, imm16/32
81h
11-100-xxx
short
alu
AND mem16/32, imm16/32
81h
mm-100-xxx
long
load, alu, store
AND mreg16/32, imm8 (signed ext.)
83h
11-100-xxx
short
alux
AND mem16/32, imm8 (signed ext.)
83h
mm-100-xxx
long
load, alux, store
ARPL mreg16, reg16
63h
11-xxx-xxx
vector
ARPL mem16, reg16
63h
mm-xxx-xxx
vector
BOUND
62h
xx-xxx-xxx
vector
BSF reg16/32, mreg16/32
0Fh
BCh
11-xxx-xxx
vector
BSF reg16/32, mem16/32
0Fh
BCh
mm-xxx-xxx
vector
BSR reg16/32, mreg16/32
0Fh
BDh
11-xxx-xxx
vector
BSR reg16/32, mem16/32
0Fh
BDh
mm-xxx-xxx
vector
BSWAP EAX
0Fh
C8h
long
alu
BSWAP ECX
0Fh
C9h
long
alu
BSWAP EDX
0Fh
CAh
long
alu
BSWAP EBX
0Fh
CBh
long
alu
BSWAP ESP
0Fh
CCh
long
alu
BSWAP EBP
0Fh
CDh
long
alu
BSWAP ESI
0Fh
CEh
long
alu
BSWAP EDI
0Fh
CFh
long
alu
BT mreg16/32, reg16/32
0Fh
A3h
11-xxx-xxx
vector
BT mem16/32, reg16/32
0Fh
A3h
mm-xxx-xxx
vector
BT mreg16/32, imm8
0Fh
BAh
11-100-xxx
vector
BT mem16/32, imm8
0Fh
BAh
mm-100-xxx
vector
BTC mreg16/32, reg16/32
0Fh
BBh
11-xxx-xxx
vector
BTC mem16/32, reg16/32
0Fh
BBh
mm-xxx-xxx
vector
BTC mreg16/32, imm8
0Fh
BAh
11-111-xxx
vector
BTC mem16/32, imm8
0Fh
BAh
mm-111-xxx
vector
BTR mreg16/32, reg16/32
0Fh
B3h
11-xxx-xxx
vector
BTR mem16/32, reg16/32
0Fh
B3h
mm-xxx-xxx
vector
BTR mreg16/32, imm8
0Fh
BAh
11-110-xxx
vector
BTR mem16/32, imm8
0Fh
BAh
mm-110-xxx
vector
52
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
RISC86®
Opcodes
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
BTS mreg16/32, reg16/32
0Fh
ABh
11-xxx-xxx
vector
BTS mem16/32, reg16/32
0Fh
ABh
mm-xxx-xxx
vector
BTS mreg16/32, imm8
0Fh
BAh
11-101-xxx
vector
BTS mem16/32, imm8
0Fh
BAh
mm-101-xxx
vector
CALL full pointer
9Ah
vector
CALL near imm16/32
E8h
short
CALL mem16:16/32
FFh
11-011-xxx
vector
CALL near mreg32 (indirect)
FFh
11-010-xxx
vector
CALL near mem32 (indirect)
FFh
mm-010-xxx
vector
CBW/CWDE EAX
98h
vector
CLC
F8h
vector
CLD
FCh
vector
CLI
FAh
vector
CLTS
0Fh
CMC
F5h
CMP mreg8, reg8
38h
11-xxx-xxx
short
alux
CMP mem8, reg8
38h
mm-xxx-xxx
short
load, alux
CMP mreg16/32, reg16/32
39h
11-xxx-xxx
short
alu
CMP mem16/32, reg16/32
39h
mm-xxx-xxx
short
load, alu
CMP reg8, mreg8
3Ah
11-xxx-xxx
short
alux
CMP reg8, mem8
3Ah
mm-xxx-xxx
short
load, alux
CMP reg16/32, mreg16/32
3Bh
11-xxx-xxx
short
alu
CMP reg16/32, mem16/32
3Bh
mm-xxx-xxx
short
load, alu
CMP AL, imm8
3Ch
xx-xxx-xxx
short
alux
CMP EAX, imm16/32
3Dh
xx-xxx-xxx
short
alu
CMP mreg8, imm8
80h
11-111-xxx
short
alux
CMP mem8, imm8
80h
mm-111-xxx
short
load, alux
CMP mreg16/32, imm16/32
81h
11-111-xxx
short
alu
CMP mem16/32, imm16/32
81h
mm-111-xxx
short
load, alu
CMP mreg16/32, imm8 (signed ext.)
83h
11-111-xxx
long
load, alu
CMP mem16/32, imm8 (signed ext.)
83h
mm-111-xxx
long
load, alu
CMPSB mem8,mem8
A6h
vector
CMPSW mem16, mem32
A7h
vector
Instruction Mnemonic
Chapter 3
06h
store
vector
vector
Software Environment
53
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RISC86®
Opcodes
Decode
Type
CMPSD mem32, mem32
A7h
CMPXCHG mreg8, reg8
0Fh
B0h
11-xxx-xxx
vector
CMPXCHG mem8, reg8
0Fh
B0h
mm-xxx-xxx
vector
CMPXCHG mreg16/32, reg16/32
0Fh
B1h
11-xxx-xxx
vector
CMPXCHG mem16/32, reg16/32
0Fh
B1h
mm-xxx-xxx
vector
CMPXCH8B EDX:EAX
0Fh
C7h
11-xxx-xxx
vector
CMPXCH8B mem64
0Fh
C7h
mm-xxx-xxx
vector
CPUID
0Fh
A2h
CWD/CDQ EDX, EAX
99h
vector
DAA
27h
vector
DAS
2Fh
vector
DEC EAX
48h
short
alu
DEC ECX
49h
short
alu
DEC EDX
4Ah
short
alu
DEC EBX
4Bh
short
alu
DEC ESP
4Ch
short
alu
DEC EBP
4Dh
short
alu
DEC ESI
4Eh
short
alu
DEC EDI
4Fh
short
alu
DEC mreg8
FEh
11-001-xxx
vector
DEC mem8
FEh
mm-001-xxx
long
DEC mreg16/32
FFh
11-001-xxx
vector
DEC mem16/32
FFh
mm-001-xxx
long
DIV AL, mreg8
F6h
11-110-xxx
vector
DIV AL, mem8
F6h
mm-110-xxx
vector
DIV EAX, mreg16/32
F7h
11-110-xxx
vector
DIV EAX, mem16/32
F7h
mm-110-xxx
vector
IDIV mreg8
F6h
11-111-xxx
vector
IDIV mem8
F6h
mm-111-xxx
vector
IDIV EAX, mreg16/32
F7h
11-111-xxx
vector
IDIV EAX, mem16/32
F7h
mm-111-xxx
vector
IMUL reg16/32, imm16/32
69h
11-xxx-xxx
vector
IMUL reg16/32, mreg16/32, imm16/32
69h
11-xxx-xxx
vector
54
vector
vector
Software Environment
load, alux, store
load, alu, store
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
IMUL reg16/32, mem16/32, imm16/32
RISC86®
Opcodes
ModR/M
Byte
Decode
Type
69h
mm-xxx-xxx
vector
IMUL reg16/32, imm8 (sign extended)
6Bh
11-xxx-xxx
vector
IMUL reg16/32, mreg16/32, imm8
(signed)
6Bh
11-xxx-xxx
vector
IMUL reg16/32, mem16/32, imm8
(signed)
6Bh
mm-xxx-xxx
vector
IMUL AX, AL, mreg8
F6h
11-101-xxx
vector
IMUL AX, AL, mem8
F6h
mm-101-xxx
vector
IMUL EDX:EAX, EAX, mreg16/32
F7h
11-101-xxx
vector
IMUL EDX:EAX, EAX, mem16/32
F7h
mm-101-xxx
vector
IMUL reg16/32, mreg16/32
0Fh
AFh
11-xxx-xxx
vector
IMUL reg16/32, mem16/32
0Fh
AFh
mm-xxx-xxx
vector
INC EAX
40h
short
alu
INC ECX
41h
short
alu
INC EDX
42h
short
alu
INC EBX
43h
short
alu
INC ESP
44h
short
alu
INC EBP
45h
short
alu
INC ESI
46h
short
alu
INC EDI
47h
short
alu
INC mreg8
FEh
11-000-xxx
vector
INC mem8
FEh
mm-000-xxx
long
INC mreg16/32
FFh
11-000-xxx
vector
INC mem16/32
FFh
mm-000-xxx
long
INVD
0Fh
08h
INVLPG
0Fh
01h
JO short disp8
70h
short
branch
JB/JNAE short disp8
71h
short
branch
JNO short disp8
71h
short
branch
JNB/JAE short disp8
73h
short
branch
JZ/JE short disp8
74h
short
branch
JNZ/JNE short disp8
75h
short
branch
JBE/JNA short disp8
76h
short
branch
Chapter 3
Second
Byte
load, alux, store
load, alu, store
vector
mm-111-xxx
Software Environment
vector
55
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
JNBE/JA short disp8
77h
short
branch
JS short disp8
78h
short
branch
JNS short disp8
79h
short
branch
JP/JPE short disp8
7Ah
short
branch
JNP/JPO short disp8
7Bh
short
branch
JL/JNGE short disp8
7Ch
short
branch
JNL/JGE short disp8
7Dh
short
branch
JLE/JNG short disp8
7Eh
short
branch
JNLE/JG short disp8
7Fh
short
branch
JCXZ/JEC short disp8
E3h
vector
JO near disp16/32
0Fh
80h
short
branch
JNO near disp16/32
0Fh
81h
short
branch
JB/JNAE near disp16/32
0Fh
82h
short
branch
JNB/JAE near disp16/32
0Fh
83h
short
branch
JZ/JE near disp16/32
0Fh
84h
short
branch
JNZ/JNE near disp16/32
0Fh
85h
short
branch
JBE/JNA near disp16/32
0Fh
86h
short
branch
JNBE/JA near disp16/32
0Fh
87h
short
branch
JS near disp16/32
0Fh
88h
short
branch
JNS near disp16/32
0Fh
89h
short
branch
JP/JPE near disp16/32
0Fh
8Ah
short
branch
JNP/JPO near disp16/32
0Fh
8Bh
short
branch
JL/JNGE near disp16/32
0Fh
8Ch
short
branch
JNL/JGE near disp16/32
0Fh
8Dh
short
branch
JLE/JNG near disp16/32
0Fh
8Eh
short
branch
JNLE/JG near disp16/32
0Fh
8Fh
short
branch
JMP near disp16/32 (direct)
E9h
short
branch
JMP far disp32/48 (direct)
EAh
vector
JMP disp8 (short)
EBh
short
JMP far mreg32 (indirect)
EFh
11-101-xxx
vector
JMP far mem32 (indirect)
EFh
mm-101-xxx
vector
JMP near mreg16/32 (indirect)
FFh
11-100-xxx
vector
JMP near mem16/32 (indirect)
FFh
mm-100-xxx
vector
56
Software Environment
branch
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RISC86®
Opcodes
Decode
Type
LAHF
9Fh
LAR reg16/32, mreg16/32
0Fh
02h
11-xxx-xxx
vector
LAR reg16/32, mem16/32
0Fh
02h
mm-xxx-xxx
vector
LDS reg16/32, mem32/48
C5h
mm-xxx-xxx
vector
LEA reg16/32, mem16/32
8Dh
mm-xxx-xxx
short
load, alu
LEAVE
C9h
long
load, alu, alu
LES reg16/32, mem32/48
C4h
LFS reg16/32, mem32/48
0Fh
B4h
LGDT mem48
0Fh
01h
LGS reg16/32, mem32/48
0Fh
B5h
LIDT mem48
0Fh
01h
mm-011-xxx
vector
LLDT mreg16
0Fh
00h
11-010-xxx
vector
LLDT mem16
0Fh
00h
mm-010-xxx
vector
LMSW mreg16
0Fh
01h
11-100-xxx
vector
LMSW mem16
0Fh
01h
mm-100-xxx
vector
LODSB AL, mem8
ACh
long
load, alux
LODSW AX, mem16
ADh
long
load, alu
LODSD EAX, mem32
ADh
long
load, alu
LOOP disp8
E2h
short
alu, branch
LOOPE/LOOPZ disp8
E1h
vector
LOOPNE/LOOPNZ disp8
E0h
vector
LSL reg16/32, mreg16/32
0Fh
03h
11-xxx-xxx
vector
LSL reg16/32, mem16/32
0Fh
03h
mm-xxx-xxx
vector
LSS reg16/32, mem32/48
0Fh
B2h
mm-xxx-xxx
vector
LTR mreg16
0Fh
00h
11-011-xxx
vector
LTR mem16
0Fh
00h
mm-011-xxx
vector
MOV mreg8, reg8
88h
11-xxx-xxx
short
alux
MOV mem8, reg8
88h
mm-xxx-xxx
short
store
MOV mreg16/32, reg16/32
89h
11-xxx-xxx
short
alu
MOV mem16/32, reg16/32
89h
mm-xxx-xxx
short
store
MOV reg8, mreg8
8Ah
11-xxx-xxx
short
alux
MOV reg8, mem8
8Ah
mm-xxx-xxx
short
load
MOV reg16/32, mreg16/32
8Bh
11-xxx-xxx
short
alu
Chapter 3
vector
mm-xxx-xxx
vector
vector
mm-010-xxx
vector
vector
Software Environment
57
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
MOV reg16/32, mem16/32
8Bh
mm-xxx-xxx
short
load
MOV mreg16, segment reg
8Ch
11-xxx-xxx
long
load
MOV mem16, segment reg
8Ch
mm-xxx-xxx
vector
MOV segment reg, mreg16
8Eh
11-xxx-xxx
vector
MOV segment reg, mem16
8Eh
mm-xxx-xxx
vector
MOV AL, mem8
A0h
short
load
MOV EAX, mem16/32
A1h
short
load
MOV mem8, AL
A2h
short
store
MOV mem16/32, EAX
A3h
short
store
MOV AL, imm8
B0h
short
limm
MOV CL, imm8
B1h
short
limm
MOV DL, imm8
B2h
short
limm
MOV BL, imm8
B3h
short
limm
MOV AH, imm8
B4h
short
limm
MOV CH, imm8
B5h
short
limm
MOV DH, imm8
B6h
short
limm
MOV BH, imm8
B7h
short
limm
MOV EAX, imm16/32
B8h
short
limm
MOV ECX, imm16/32
B9h
short
limm
MOV EDX, imm16/32
BAh
short
limm
MOV EBX, imm16/32
BBh
short
limm
MOV ESP, imm16/32
BCh
short
limm
MOV EBP, imm16/32
BDh
short
limm
MOV ESI, imm16/32
BEh
short
limm
MOV EDI, imm16/32
BFh
short
limm
MOV mreg8, imm8
C6h
11-000-xxx
short
limm
MOV mem8, imm8
C6h
mm-000-xxx
long
store
MOV reg16/32, imm16/32
C7h
11-000-xxx
short
limm
MOV mem16/32, imm16/32
C7h
mm-000-xxx
long
store
MOVSB mem8,mem8
A4h
long
load, store, alux, alux
MOVSD mem16, mem16
A5h
long
load, store, alu, alu
MOVSW mem32, mem32
A5h
long
load, store, alu, alu
MOVSX reg16/32, mreg8
0Fh
short
alu
58
BEh
11-xxx-xxx
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
RISC86®
Opcodes
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
MOVSX reg16/32, mem8
0Fh
BEh
mm-xxx-xxx
short
load, alu
MOVSX reg32, mreg16
0Fh
BFh
11-xxx-xxx
short
alu
MOVSX reg32, mem16
0Fh
BFh
mm-xxx-xxx
short
load, alu
MOVZX reg16/32, mreg8
0Fh
B6h
11-xxx-xxx
short
alu
MOVZX reg16/32, mem8
0Fh
B6h
mm-xxx-xxx
short
load, alu
MOVZX reg32, mreg16
0Fh
B7h
11-xxx-xxx
short
alu
MOVZX reg32, mem16
0Fh
B7h
mm-xxx-xxx
short
load, alu
MUL AL, mreg8
F6h
11-100-xxx
vector
MUL AL, mem8
F6h
mm-100-xxx
vector
MUL EAX, mreg16/32
F7h
11-100-xxx
vector
MUL EAX, mem16/32
F7h
mm-100-xxx
vector
NEG mreg8
F6h
11-011-xxx
short
NEG mem8
F6h
mm-011-xxx
vector
NEG mreg16/32
F7h
11-011-xxx
short
NEG mem16/32
F7h
mm-011-xxx
vector
NOP (XCHG AX, AX)
90h
NOT mreg8
F6h
NOT mem8
Instruction Mnemonic
alux
alu
short
limm
11-010-xxx
short
alux
F6h
mm-010-xxx
vector
NOT mreg16/32
F7h
11-010-xxx
short
NOT mem16/32
F7h
mm-010-xxx
vector
OR mreg8, reg8
08h
11-xxx-xxx
short
alux
OR mem8, reg8
08h
mm-xxx-xxx
long
load, alux, store
OR mreg16/32, reg16/32
09h
11-xxx-xxx
short
alu
OR mem16/32, reg16/32
09h
mm-xxx-xxx
long
load, alu, store
OR reg8, mreg8
0Ah
11-xxx-xxx
short
alux
OR reg8, mem8
0Ah
mm-xxx-xxx
short
load, alux
OR reg16/32, mreg16/32
0Bh
11-xxx-xxx
short
alu
OR reg16/32, mem16/32
0Bh
mm-xxx-xxx
short
load, alu
OR AL, imm8
0Ch
xx-xxx-xxx
short
alux
OR EAX, imm16/32
0Dh
xx-xxx-xxx
short
alu
OR mreg8, imm8
80h
11-001-xxx
short
alux
OR mem8, imm8
80h
mm-001-xxx
long
load, alux, store
OR mreg16/32, imm16/32
81h
11-001-xxx
short
alu
Chapter 3
Software Environment
alu
59
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
OR mem16/32, imm16/32
81h
mm-001-xxx
long
load, alu, store
OR mreg16/32, imm8 (signed ext.)
83h
11-001-xxx
short
alux
OR mem16/32, imm8 (signed ext.)
83h
mm-001-xxx
long
load, alux, store
POP ES
07h
vector
POP SS
17h
vector
POP DS
1Fh
vector
POP FS
0Fh
A1h
vector
POP GS
0Fh
A9h
vector
POP EAX
58h
short
load, alu
POP ECX
59h
short
load, alu
POP EDX
5Ah
short
load, alu
POP EBX
5Bh
short
load, alu
POP ESP
5Ch
short
load, alu
POP EBP
5Dh
short
load, alu
POP ESI
5Eh
short
load, alu
POP EDI
5Fh
short
load, alu
POP mreg
8Fh
11-000-xxx
short
load, alu
POP mem
8Fh
mm-000-xxx
long
load, store, alu
POPA/POPAD
61h
vector
POPF/POPFD
9Dh
vector
PUSH ES
06h
long
PUSH CS
0Eh
vector
PUSH FS
0Fh
A0h
vector
PUSH GS
0Fh
A8h
vector
PUSH SS
16h
vector
PUSH DS
1Eh
long
load, store
PUSH EAX
50h
short
store
PUSH ECX
51h
short
store
PUSH EDX
52h
short
store
PUSH EBX
53h
short
store
PUSH ESP
54h
short
store
PUSH EBP
55h
short
store
PUSH ESI
56h
short
store
60
Software Environment
load, store
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RISC86®
Opcodes
Decode
Type
PUSH EDI
57h
short
store
PUSH imm8
6Ah
long
store
PUSH imm16/32
68h
long
store
PUSH mreg16/32
FFh
11-110-xxx
vector
PUSH mem16/32
FFh
mm-110-xxx
long
PUSHA/PUSHAD
60h
vector
PUSHF/PUSHFD
9Ch
vector
RCL mreg8, imm8
C0h
11-010-xxx
vector
RCL mem8, imm8
C0h
mm-010-xxx
vector
RCL mreg16/32, imm8
C1h
11-010-xxx
vector
RCL mem16/32, imm8
C1h
mm-010-xxx
vector
RCL mreg8, 1
D0h
11-010-xxx
vector
RCL mem8, 1
D0h
mm-010-xxx
vector
RCL mreg16/32, 1
D1h
11-010-xxx
vector
RCL mem16/32, 1
D1h
mm-010-xxx
vector
RCL mreg8, CL
D2h
11-010-xxx
vector
RCL mem8, CL
D2h
mm-010-xxx
vector
RCL mreg16/32, CL
D3h
11-010-xxx
vector
RCL mem16/32, CL
D3h
mm-010-xxx
vector
RCR mreg8, imm8
C0h
11-011-xxx
vector
RCR mem8, imm8
C0h
mm-011-xxx
vector
RCR mreg16/32, imm8
C1h
11-011-xxx
vector
RCR mem16/32, imm8
C1h
mm-011-xxx
vector
RCR mreg8, 1
D0h
11-011-xxx
vector
RCR mem8, 1
D0h
mm-011-xxx
vector
RCR mreg16/32, 1
D1h
11-011-xxx
vector
RCR mem16/32, 1
D1h
mm-011-xxx
vector
RCR mreg8, CL
D2h
11-011-xxx
vector
RCR mem8, CL
D2h
mm-011-xxx
vector
RCR mreg16/32, CL
D3h
11-011-xxx
vector
RCR mem16/32, CL
D3h
mm-011-xxx
vector
RET near imm16
C2h
vector
RET near
C3h
vector
Chapter 3
Software Environment
load, store
61
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RET far imm16
CAh
vector
RET far
CBh
vector
ROL mreg8, imm8
C0h
11-000-xxx
vector
ROL mem8, imm8
C0h
mm-000-xxx
vector
ROL mreg16/32, imm8
C1h
11-000-xxx
vector
ROL mem16/32, imm8
C1h
mm-000-xxx
vector
ROL mreg8, 1
D0h
11-000-xxx
vector
ROL mem8, 1
D0h
mm-000-xxx
vector
ROL mreg16/32, 1
D1h
11-000-xxx
vector
ROL mem16/32, 1
D1h
mm-000-xxx
vector
ROL mreg8, CL
D2h
11-000-xxx
vector
ROL mem8, CL
D2h
mm-000-xxx
vector
ROL mreg16/32, CL
D3h
11-000-xxx
vector
ROL mem16/32, CL
D3h
mm-000-xxx
vector
ROR mreg8, imm8
C0h
11-001-xxx
vector
ROR mem8, imm8
C0h
mm-001-xxx
vector
ROR mreg16/32, imm8
C1h
11-001-xxx
vector
ROR mem16/32, imm8
C1h
mm-001-xxx
vector
ROR mreg8, 1
D0h
11-001-xxx
vector
ROR mem8, 1
D0h
mm-001-xxx
vector
ROR mreg16/32, 1
D1h
11-001-xxx
vector
ROR mem16/32, 1
D1h
mm-001-xxx
vector
ROR mreg8, CL
D2h
11-001-xxx
vector
ROR mem8, CL
D2h
mm-001-xxx
vector
ROR mreg16/32, CL
D3h
11-001-xxx
vector
ROR mem16/32, CL
D3h
mm-001-xxx
vector
SAHF
9Eh
SAR mreg8, imm8
C0h
11-111-xxx
short
SAR mem8, imm8
C0h
mm-111-xxx
vector
SAR mreg16/32, imm8
C1h
11-111-xxx
short
SAR mem16/32, imm8
C1h
mm-111-xxx
vector
SAR mreg8, 1
D0h
11-111-xxx
short
SAR mem8, 1
D0h
mm-111-xxx
vector
62
RISC86®
Opcodes
Decode
Type
vector
Software Environment
alux
alu
alux
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
SAR mreg16/32, 1
D1h
11-111-xxx
short
SAR mem16/32, 1
D1h
mm-111-xxx
vector
SAR mreg8, CL
D2h
11-111-xxx
short
SAR mem8, CL
D2h
mm-111-xxx
vector
SAR mreg16/32, CL
D3h
11-111-xxx
short
SAR mem16/32, CL
D3h
mm-111-xxx
vector
SBB mreg8, reg8
18h
11-xxx-xxx
short
alux
SBB mem8, reg8
18h
mm-xxx-xxx
long
load, alux, store
SBB mreg16/32, reg16/32
19h
11-xxx-xxx
short
alu
SBB mem16/32, reg16/32
19h
mm-xxx-xxx
long
load, alu, store
SBB reg8, mreg8
1Ah
11-xxx-xxx
short
alux
SBB reg8, mem8
1Ah
mm-xxx-xxx
short
load, alux
SBB reg16/32, mreg16/32
1Bh
11-xxx-xxx
short
alu
SBB reg16/32, mem16/32
1Bh
mm-xxx-xxx
short
load, alu
SBB AL, imm8
1Ch
xx-xxx-xxx
short
alux
SBB EAX, imm16/32
1Dh
xx-xxx-xxx
short
alu
SBB mreg8, imm8
80h
11-011-xxx
short
alux
SBB mem8, imm8
80h
mm-011-xxx
long
load, alux, store
SBB mreg16/32, imm16/32
81h
11-011-xxx
short
alu
SBB mem16/32, imm16/32
81h
mm-011-xxx
long
load, alu, store
SBB mreg8, imm8 (signed ext.)
83h
11-011-xxx
short
alux
SBB mem8, imm8 (signed ext.)
83h
mm-011-xxx
long
load, alux, store
SCASB AL, mem8
AEh
vector
SCASW AX, mem16
AFh
vector
SCASD EAX, mem32
AFh
vector
SETO mreg8
0Fh
90h
11-xxx-xxx
vector
SETO mem8
0Fh
90h
mm-xxx-xxx
vector
SETNO mreg8
0Fh
91h
11-xxx-xxx
vector
SETNO mem8
0Fh
91h
mm-xxx-xxx
vector
SETB/SETNAE mreg8
0Fh
92h
11-xxx-xxx
vector
SETB/SETNAE mem8
0Fh
92h
mm-xxx-xxx
vector
SETNB/SETAE mreg8
0Fh
93h
11-xxx-xxx
vector
SETNB/SETAE mem8
0Fh
93h
mm-xxx-xxx
vector
Chapter 3
Software Environment
alu
alux
alu
63
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
SETZ/SETE mreg8
0Fh
94h
11-xxx-xxx
vector
SETZ/SETE mem8
0Fh
94h
mm-xxx-xxx
vector
SETNZ/SETNE mreg8
0Fh
95h
11-xxx-xxx
vector
SETNZ/SETNE mem8
0Fh
95h
mm-xxx-xxx
vector
SETBE/SETNA mreg8
0Fh
96h
11-xxx-xxx
vector
SETBE/SETNA mem8
0Fh
96h
mm-xxx-xxx
vector
SETNBE/SETA mreg8
0Fh
97h
11-xxx-xxx
vector
SETNBE/SETA mem8
0Fh
97h
mm-xxx-xxx
vector
SETS mreg8
0Fh
98h
11-xxx-xxx
vector
SETS mem8
0Fh
98h
mm-xxx-xxx
vector
SETNS mreg8
0Fh
99h
11-xxx-xxx
vector
SETNS mem8
0Fh
99h
mm-xxx-xxx
vector
SETP/SETPE mreg8
0Fh
9Ah
11-xxx-xxx
vector
SETP/SETPE mem8
0Fh
9Ah
mm-xxx-xxx
vector
SETNP/SETPO mreg8
0Fh
9Bh
11-xxx-xxx
vector
SETNP/SETPO mem8
0Fh
9Bh
mm-xxx-xxx
vector
SETL/SETNGE mreg8
0Fh
9Ch
11-xxx-xxx
vector
SETL/SETNGE mem8
0Fh
9Ch
mm-xxx-xxx
vector
SETNL/SETGE mreg8
0Fh
9Dh
11-xxx-xxx
vector
SETNL/SETGE mem8
0Fh
9Dh
mm-xxx-xxx
vector
SETLE/SETNG mreg8
0Fh
9Eh
11-xxx-xxx
vector
SETLE/SETNG mem8
0Fh
9Eh
mm-xxx-xxx
vector
SETNLE/SETG mreg8
0Fh
9Fh
11-xxx-xxx
vector
SETNLE/SETG mem8
0Fh
9Fh
mm-xxx-xxx
vector
SGDT mem48
0Fh
01h
mm-000-xxx
vector
SIDT mem48
0Fh
01h
mm-001-xxx
vector
SHL/SAL mreg8, imm8
C0h
11-100-xxx
short
SHL/SAL mem8, imm8
C0h
mm-100-xxx
vector
SHL/SAL mreg16/32, imm8
C1h
11-100-xxx
short
SHL/SAL mem16/32, imm8
C1h
mm-100-xxx
vector
SHL/SAL mreg8, 1
D0h
11-100-xxx
short
SHL/SAL mem8, 1
D0h
mm-100-xxx
vector
SHL/SAL mreg16/32, 1
D1h
11-100-xxx
short
Instruction Mnemonic
64
Software Environment
RISC86®
Opcodes
alux
alu
alux
alu
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
SHL/SAL mem16/32, 1
D1h
mm-100-xxx
vector
SHL/SAL mreg8, CL
D2h
11-100-xxx
short
SHL/SAL mem8, CL
D2h
mm-100-xxx
vector
SHL/SAL mreg16/32, CL
D3h
11-100-xxx
short
SHL/SAL mem16/32, CL
D3h
mm-100-xxx
vector
SHR mreg8, imm8
C0h
11-101-xxx
short
SHR mem8, imm8
C0h
mm-101-xxx
vector
SHR mreg16/32, imm8
C1h
11-101-xxx
short
SHR mem16/32, imm8
C1h
mm-101-xxx
vector
SHR mreg8, 1
D0h
11-101-xxx
short
SHR mem8, 1
D0h
mm-101-xxx
vector
SHR mreg16/32, 1
D1h
11-101-xxx
short
SHR mem16/32, 1
D1h
mm-101-xxx
vector
SHR mreg8, CL
D2h
11-101-xxx
short
SHR mem8, CL
D2h
mm-101-xxx
vector
SHR mreg16/32, CL
D3h
11-101-xxx
short
SHR mem16/32, CL
D3h
mm-101-xxx
vector
SHLD mreg16/32, reg16/32, imm8
0Fh
A4h
11-xxx-xxx
vector
SHLD mem16/32, reg16/32, imm8
0Fh
A4h
mm-xxx-xxx
vector
SHLD mreg16/32, reg16/32, CL
0Fh
A5h
11-xxx-xxx
vector
SHLD mem16/32, reg16/32, CL
0Fh
A5h
mm-xxx-xxx
vector
SHRD mreg16/32, reg16/32, imm8
0Fh
ACh
11-xxx-xxx
vector
SHRD mem16/32, reg16/32, imm8
0Fh
ACh
mm-xxx-xxx
vector
SHRD mreg16/32, reg16/32, CL
0Fh
ADh
11-xxx-xxx
vector
SHRD mem16/32, reg16/32, CL
0Fh
ADh
mm-xxx-xxx
vector
SLDT mreg16
0Fh
00h
11-000-xxx
vector
SLDT mem16
0Fh
00h
mm-000-xxx
vector
SMSW mreg16
0Fh
01h
11-100-xxx
vector
SMSW mem16
0Fh
01h
mm-100-xxx
vector
STC
F9h
vector
STD
FDh
vector
STI
FBh
vector
STOSB mem8, AL
AAh
long
Chapter 3
Software Environment
RISC86®
Opcodes
alux
alu
alux
alu
alux
alu
alux
alu
store, alux
65
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
RISC86®
Opcodes
Decode
Type
STOSW mem16, AX
ABh
long
store, alu
STOSD mem32, EAX
ABh
long
store, alu
STR mreg16
0Fh
00h
11-001-xxx
vector
STR mem16
0Fh
00h
mm-001-xxx
vector
SUB mreg8, reg8
28h
11-xxx-xxx
short
alux
SUB mem8, reg8
28h
mm-xxx-xxx
long
load, alux, store
SUB mreg16/32, reg16/32
29h
11-xxx-xxx
short
alu
SUB mem16/32, reg16/32
29h
mm-xxx-xxx
long
load, alu, store
SUB reg8, mreg8
2Ah
11-xxx-xxx
short
alux
SUB reg8, mem8
2Ah
mm-xxx-xxx
short
load, alux
SUB reg16/32, mreg16/32
2Bh
11-xxx-xxx
short
alu
SUB reg16/32, mem16/32
2Bh
mm-xxx-xxx
short
load, alu
SUB AL, imm8
2Ch
xx-xxx-xxx
short
alux
SUB EAX, imm16/32
2Dh
xx-xxx-xxx
short
alu
SUB mreg8, imm8
80h
11-101-xxx
short
alux
SUB mem8, imm8
80h
mm-101-xxx
long
load, alux, store
SUB mreg16/32, imm16/32
81h
11-101-xxx
short
alu
SUB mem16/32, imm16/32
81h
mm-101-xxx
long
load, alu, store
SUB mreg16/32, imm8 (signed ext.)
83h
11-101-xxx
short
alux
SUB mem16/32, imm8 (signed ext.)
83h
mm-101-xxx
long
load, alux, store
TEST mreg8, reg8
84h
11-xxx-xxx
short
alux
TEST mem8, reg8
84h
mm-xxx-xxx
vector
TEST mreg16/32, reg16/32
85h
11-xxx-xxx
short
TEST mem16/32, reg16/32
85h
mm-xxx-xxx
vector
TEST AL, imm8
A8h
long
alux
TEST EAX, Imm16/32
A9h
long
alu
TEST mreg8, imm8
F6h
11-000-xxx
long
alux
TEST mem8, imm8
F6h
mm-000-xxx
long
load, alux
TEST mreg8, imm16/32
F7h
11-000-xxx
long
alu
TEST mem8, imm16/32
F7h
mm-000-xxx
long
load, alu
VERR mreg16
0Fh
00h
11-100-xxx
vector
VERR mem16
0Fh
00h
mm-100-xxx
vector
VERW mreg16
0Fh
00h
11-101-xxx
vector
66
Software Environment
alu
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
RISC86®
Opcodes
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
VERW mem16
0Fh
00h
mm-101-xxx
vector
WAIT
9Bh
WBINVD
0Fh
09h
XADD mreg8, reg8
0Fh
C0h
11-100-xxx
vector
XADD mem8, reg8
0Fh
C0h
mm-100-xxx
vector
XADD mreg16/32, reg16/32
0Fh
C1h
11-101-xxx
vector
XADD mem16/32, reg16/32
0Fh
C1h
mm-101-xxx
vector
XCHG reg8, mreg8
86h
11-xxx-xxx
vector
XCHG reg8, mem8
86h
mm-xxx-xxx
vector
XCHG reg16/32, mreg16/32
87h
11-xxx-xxx
vector
XCHG reg16/32, mem16/32
87h
mm-xxx-xxx
vector
XCHG EAX, EAX
90h
short
limm
XCHG EAX, ECX
91h
long
alu, alu, alu
XCHG EAX, EDX
92h
long
alu, alu, alu
XCHG EAX, EBX
93h
long
alu, alu, alu
XCHG EAX, ESP
94h
long
alu, alu, alu
XCHG EAX, EBP
95h
long
alu, alu, alu
XCHG EAX, ESI
96h
long
alu, alu, alu
XCHG EAX, EDI
97h
long
alu, alu, alu
XLAT
D7h
vector
XOR mreg8, reg8
30h
11-xxx-xxx
short
alux
XOR mem8, reg8
30h
mm-xxx-xxx
long
load, alux, store
XOR mreg16/32, reg16/32
31h
11-xxx-xxx
short
alu
XOR mem16/32, reg16/32
31h
mm-xxx-xxx
long
load, alu, store
XOR reg8, mreg8
32h
11-xxx-xxx
short
alux
XOR reg8, mem8
32h
mm-xxx-xxx
short
load, alux
XOR reg16/32, mreg16/32
33h
11-xxx-xxx
short
alu
XOR reg16/32, mem16/32
33h
mm-xxx-xxx
short
load, alu
XOR AL, imm8
34h
xx-xxx-xxx
short
alux
XOR EAX, imm16/32
35h
xx-xxx-xxx
short
alu
XOR mreg8, imm8
80h
11-110-xxx
short
alux
XOR mem8, imm8
80h
mm-110-xxx
long
load, alux, store
XOR mreg16/32, imm16/32
81h
11-110-xxx
short
alu
Instruction Mnemonic
Chapter 3
vector
vector
Software Environment
67
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 10. Integer Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
XOR mem16/32, imm16/32
81h
mm-110-xxx
long
load, alu, store
XOR mreg16/32, imm8 (signed ext.)
83h
11-110-xxx
short
alux
XOR mem16/32, imm8 (signed ext.)
83h
mm-110-xxx
long
load, alux, store
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
Table 11. Floating-Point Instructions
First
Byte
Second
Byte
F2XM1
D9h
F0h
short
float
FABS
D9h
F1h
short
float
FADD ST(0), ST(i)
D8h
11-000-xxx
short
float
FADD ST(0), mem32real
D8h
mm-000-xxx
short
fload, float
FADD ST(i), ST(0)
DCh
11-000-xxx
short
float
FADD ST(0), mem64real
DCh
mm-000-xxx
short
fload, float
FADDP ST(i), ST(0)
DEh
11-000-xxx
short
float
FBLD
DFh
mm-100-xxx
vector
*
FBSTP
DFh
mm-110-xxx
vector
*
FCHS
D9h
E0h
short
FCLEX
DBh
E2h
vector
FCOM ST(0), ST(i)
D8h
11-010-xxx
short
float
FCOM ST(0), mem32real
D8h
mm-010-xxx
short
fload, float
FCOM ST(0), mem64real
DCh
mm-010-xxx
short
fload, float
FCOMP ST(0), ST(i)
D8h
11-011-xxx
short
float
FCOMP ST(0), mem32real
D8h
mm-011-xxx
short
fload, float
FCOMP ST(0), mem64real
DCh
mm-011-xxx
short
fload, float
FCOMPP
DEh
11-011-001
short
float
FCOS ST(0)
D9h
FFh
short
float
FDECSTP
D9h
F6h
short
float
FDIV ST(0), ST(i) (single precision)
D8h
11-110-xxx
short
float
*
FDIV ST(0), ST(i) (double precision)
D8h
11-110-xxx
short
float
*
FDIV ST(0), ST(i) (extended precision)
D8h
11-110-xxx
short
float
*
Instruction Mnemonic
Note
*
*
*
float
*
*
Note:
*
68
The last three bits of the modR/M byte select the stack entry ST(i).
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 11. Floating-Point Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
Note
FDIV ST(i), ST(0) (single precision)
DCh
11-111-xxx
short
float
*
FDIV ST(i), ST(0) (double precision)
DCh
11-111-xxx
short
float
*
FDIV ST(i), ST(0) (extended precision)
DCh
11-111-xxx
short
float
*
FDIV ST(0), mem32real
D8h
mm-110-xxx
short
fload, float
FDIV ST(0), mem64real
DCh
mm-110-xxx
short
fload, float
FDIVP ST(0), ST(i)
DEh
11-111-xxx
short
float
*
FDIVR ST(0), ST(i)
D8h
11-110-xxx
short
float
*
FDIVR ST(I), ST(0)
DCh
11-111-xxx
short
float
*
FDIVR ST(0), mem32real
D8h
mm-111-xxx
short
fload, float
FDIVR ST(0), mem64real
DCh
mm-111-xxx
short
fload, float
FDIVRP ST(i), ST(0)
DEh
11-110-xxx
short
float
*
FFREE ST(I)
DDh
11-000-xxx
short
float
*
FIADD ST(0), mem32int
DAh
mm-000-xxx
short
fload, float
FIADD ST(0), mem16int
DEh
mm-000-xxx
short
fload, float
FICOM ST(0), mem32int
DAh
mm-010-xxx
short
fload, float
FICOM ST(0), mem16int
DEh
mm-010-xxx
short
fload, float
FICOMP ST(0), mem32int
DAh
mm-011-xxx
short
fload, float
FICOMP ST(0), mem16int
DEh
mm-011-xxx
short
fload, float
FIDIV ST(0), mem32int
DAh
mm-110-xxx
short
fload, float
FIDIV ST(0), mem16int
DEh
mm-110-xxx
short
fload, float
FIDIVR ST(0), mem32int
DAh
mm-111-xxx
short
fload, float
FIDIVR ST(0), mem16int
DEh
mm-111-xxx
short
fload, float
FILD mem16int
DFh
mm-000-xxx
short
fload, float
FILD mem32int
DBh
mm-000-xxx
short
fload, float
FILD mem64int
DFh
mm-101-xxx
short
fload, float
FIMUL ST(0), mem32int
DAh
mm-001-xxx
short
fload, float
FIMUL ST(0), mem16int
DEh
mm-001-xxx
short
fload, float
FINCSTP
D9h
F7h
short
float
FINIT
DBh
E3h
vector
FIST mem16int
DFh
mm-010-xxx
short
fload, float
FIST mem32int
DBh
mm-010-xxx
short
fload, float
Note:
*
The last three bits of the modR/M byte select the stack entry ST(i).
Chapter 3
Software Environment
69
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 11. Floating-Point Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
Note
FISTP mem16int
DFh
mm-011-xxx
short
fload, float
FISTP mem32int
DBh
mm-011-xxx
short
fload, float
FISTP mem64int
DFh
mm-111-xxx
short
fload, float
FISUB ST(0), mem32int
DAh
mm-100-xxx
short
fload, float
FISUB ST(0), mem16int
DEh
mm-100-xxx
short
fload, float
FISUBR ST(0), mem32int
DAh
mm-101-xxx
short
fload, float
FISUBR ST(0), mem16int
DEh
mm-101-xxx
short
fload, float
FLD ST(i)
D9h
11-000-xxx
short
fload, float
FLD mem32real
D9h
mm-000-xxx
short
fload, float
FLD mem64real
DDh
mm-000-xxx
short
fload, float
FLD mem80real
DBh
mm-101-xxx
vector
FLD1
D9h
FLDCW
D9h
mm-101-xxx
vector
FLDENV
D9h
mm-100-xxx
short
fload, float
FLDL2E
D9h
EAh
short
float
FLDL2T
D9h
E9h
short
float
FLDLG2
D9h
ECh
short
float
FLDLN2
D9h
EDh
short
float
FLDPI
D9h
EBh
short
float
FLDZ
D9h
EEh
short
float
FMUL ST(0), ST(i)
D8h
11-001-xxx
short
float
*
FMUL ST(i), ST(0)
DCh
11-001-xxx
short
float
*
FMUL ST(0), mem32real
D8h
mm-001-xxx
short
fload, float
FMUL ST(0), mem64real
DCh
mm-001-xxx
short
fload, float
FMULP ST(0), ST(i)
DEh
11-001-xxx
short
float
FNOP
D9h
D0h
short
float
FPATAN
D9h
F3h
short
float
FPREM
D9h
F8h
short
float
FPREM1
D9h
F5h
short
float
FPTAN
D9h
F2h
vector
FRNDINT
D9h
FCh
short
E8h
short
*
fload, float
float
Note:
*
70
The last three bits of the modR/M byte select the stack entry ST(i).
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 11. Floating-Point Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
FRSTOR
DDh
mm-100-xxx
vector
FSAVE
DDh
mm-110-xxx
vector
FSCALE
D9h
FDh
short
float
FSIN
D9h
FEh
short
float
FSINCOS
D9h
FBh
vector
FSQRT (single precision)
D9h
FAh
short
float
FSQRT (double precision)
D9h
FAh
short
float
FSQRT (extended precision)
D9h
FAh
short
float
FST mem32real
D9h
mm-010-xxx
short
fstore
FST mem64real
DDh
mm-010-xxx
short
fstore
FST ST(i)
DDh
11-010xxx
short
fstore
FSTCW
D9h
mm-111-xxx
vector
FSTENV
D9h
mm-110-xxx
vector
FSTP mem32real
D9h
mm-011-xxx
short
fstore
FSTP mem64real
DDh
mm-011-xxx
short
fstore
FSTP mem80real
D9h
mm-111-xxx
vector
FSTP ST(i)
DDh
11-011-xxx
short
FSTSW AX
DFh
FSTSW mem16
DDh
mm-111-xxx
vector
FSUB ST(0), mem32real
D8h
mm-100-xxx
short
fload, float
FSUB ST(0), mem64real
DCh
mm-100-xxx
short
fload, float
FSUB ST(0), ST(i)
D8h
11-100-xxx
short
float
FSUB ST(i), ST(0)
DCh
11-101-xxx
short
float
FSUBP ST(0), ST(I)
DEh
11-101-xxx
short
float
FSUBR ST(0), mem32real
D8h
mm-101-xxx
short
fload, float
FSUBR ST(0), mem64real
DCh
mm-101-xxx
short
fload, float
FSUBR ST(0), ST(I)
D8h
11-100-xxx
short
float
FSUBR ST(i), ST(0)
DCh
11-101-xxx
short
float
FSUBRP ST(i), ST(0)
DEh
11-100-xxx
short
float
FTST
D9h
short
float
FUCOM
DDh
short
float
E0h
Note
float
vector
E4h
11-100-xxx
Note:
*
The last three bits of the modR/M byte select the stack entry ST(i).
Chapter 3
Software Environment
71
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 11. Floating-Point Instructions (continued)
Instruction Mnemonic
First
Byte
Second
Byte
RISC86®
Opcodes
ModR/M
Byte
Decode
Type
11-101-xxx
short
float
FUCOMP
DDh
FUCOMPP
DAh
E9h
short
float
FXAM
D9h
E5h
short
float
FXCH
D9h
short
float
FXTRACT
D9h
F4h
vector
FYL2X
D9h
F1h
short
float
FYL2XP1
D9h
F9h
short
float
FWAIT
9Bh
11-001-xxx
Note
vector
Note:
*
The last three bits of the modR/M byte select the stack entry ST(i).
Table 12. MMX™ Instructions
Instruction Mnemonic
Prefix First
Byte(s) Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
EMMS
0Fh
77h
MOVD mmreg, mreg32
0Fh
6Eh
11-xxx-xxx
short
store, mload
MOVD mmreg, mem32
0Fh
6Eh
mm-xxx-xxx
short
mload
MOVD mreg32, mmreg
0Fh
7Eh
11-xxx-xxx
short
mstore, load
MOVD mem32, mmreg
0Fh
7Eh
mm-xxx-xxx
short
mstore
MOVQ mmreg1, mmreg2
0Fh
6Fh
11-xxx-xxx
short
meu
MOVQ mmreg, mem64
0Fh
6Fh
mm-xxx-xxx
short
mload
MOVQ mmreg1, mmreg2
0Fh
7Fh
11-xxx-xxx
short
meu
MOVQ mem64, mmreg
0Fh
7Fh
mm-xxx-xxx
short
mstore
PACKSSDW mmreg1, mmreg2
0Fh
6Bh
11-xxx-xxx
short
meu
PACKSSDW mmreg, mem64
0Fh
6Bh
mm-xxx-xxx
short
mload, meu
PACKSSWB mmreg1, mmreg2
0Fh
63h
11-xxx-xxx
short
meu
PACKSSWB mmreg, mem64
0Fh
64h
mm-xxx-xxx
short
mload, meu
PACKUSWB mmreg1, mmreg2
0Fh
67h
11-xxx-xxx
short
meu
PACKUSWB mmreg, mem64
0Fh
67h
mm-xxx-xxx
short
mload, meu
PADDB mmreg1, mmreg2
0Fh
FCh
11-xxx-xxx
short
meu
PADDB mmreg, mem64
0Fh
FCh
mm-xxx-xxx
short
mload, meu
Note
vector
*
*
Note:
*
72
Bits 2, 1, and 0 of the modR/M byte select the integer register.
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 12. MMX™ Instructions (continued)
Instruction Mnemonic
Prefix First
Byte(s) Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
PADDD mmreg1, mmreg2
0Fh
FEh
11-xxx-xxx
short
meu
PADDD mmreg, mem64
0Fh
FEh
mm-xxx-xxx
short
mload, meu
PADDSB mmreg1, mmreg2
0Fh
ECh
11-xxx-xxx
short
meu
PADDSB mmreg, mem64
0Fh
ECh
mm-xxx-xxx
short
mload, meu
PADDSW mmreg1, mmreg2
0Fh
EDh
11-xxx-xxx
short
meu
PADDSW mmreg, mem64
0Fh
EDh
mm-xxx-xxx
short
mload, meu
PADDUSB mmreg1, mmreg2
0Fh
DCh
11-xxx-xxx
short
meu
PADDUSB mmreg, mem64
0Fh
DCh
mm-xxx-xxx
short
mload, meu
PADDUSW mmreg1, mmreg2
0Fh
DDh
11-xxx-xxx
short
meu
PADDUSW mmreg, mem64
0Fh
DDh
mm-xxx-xxx
short
mload, meu
PADDW mmreg1, mmreg2
0Fh
FDh
11-xxx-xxx
short
meu
PADDW mmreg, mem64
0Fh
FDh
mm-xxx-xxx
short
mload, meu
PAND mmreg1, mmreg2
0Fh
DBh
11-xxx-xxx
short
meu
PAND mmreg, mem64
0Fh
DBh
mm-xxx-xxx
short
mload, meu
PANDN mmreg1, mmreg2
0Fh
DFh
11-xxx-xxx
short
meu
PANDN mmreg, mem64
0Fh
DFh
mm-xxx-xxx
short
mload, meu
PCMPEQB mmreg1, mmreg2
0Fh
74h
11-xxx-xxx
short
meu
PCMPEQB mmreg, mem64
0Fh
74h
mm-xxx-xxx
short
mload, meu
PCMPEQD mmreg1, mmreg2
0Fh
76h
11-xxx-xxx
short
meu
PCMPEQD mmreg, mem64
0Fh
76h
mm-xxx-xxx
short
mload, meu
PCMPEQW mmreg1, mmreg2
0Fh
75h
11-xxx-xxx
short
meu
PCMPEQW mmreg, mem64
0Fh
75h
mm-xxx-xxx
short
mload, meu
PCMPGTB mmreg1, mmreg2
0Fh
64h
11-xxx-xxx
short
meu
PCMPGTB mmreg, mem64
0Fh
64h
mm-xxx-xxx
short
mload, meu
PCMPGTD mmreg1, mmreg2
0Fh
66h
11-xxx-xxx
short
meu
PCMPGTD mmreg, mem64
0Fh
66h
mm-xxx-xxx
short
mload, meu
PCMPGTW mmreg1, mmreg2
0Fh
65h
11-xxx-xxx
short
meu
PCMPGTW mmreg, mem64
0Fh
65h
mm-xxx-xxx
short
mload, meu
PMADDWD mmreg1, mmreg2
0Fh
F5h
11-xxx-xxx
short
meu
PMADDWD mmreg, mem64
0Fh
F5h
mm-xxx-xxx
short
mload, meu
PMULHW mmreg1, mmreg2
0Fh
E5h
11-xxx-xxx
short
meu
Note
Note:
*
Bits 2, 1, and 0 of the modR/M byte select the integer register.
Chapter 3
Software Environment
73
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 12. MMX™ Instructions (continued)
Instruction Mnemonic
Prefix First
Byte(s) Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
PMULHW mmreg, mem64
0Fh
E5h
mm-xxx-xxx
short
mload, meu
PMULLW mmreg1, mmreg2
0Fh
D5h
11-xxx-xxx
short
meu
PMULLW mmreg, mem64
0Fh
D5h
mm-xxx-xxx
short
mload, meu
POR mmreg1, mmreg2
0Fh
EBh
11-xxx-xxx
short
meu
POR mmreg, mem64
0Fh
EBh
mm-xxx-xxx
short
mload, meu
PSLLW mmreg1, mmreg2
0Fh
F1h
11-xxx-xxx
short
meu
PSLLW mmreg, mem64
0Fh
F1h
11-xxx-xxx
short
mload, meu
PSLLW mmreg, imm8
0Fh
71h
11-110-xxx
short
meu
PSLLD mmreg1, mmreg2
0Fh
F2h
11-xxx-xxx
short
meu
PSLLD mmreg, mem64
0Fh
F2h
11-xxx-xxx
short
meu
PSLLD mmreg, imm8
0Fh
72h
11-110-xxx
short
meu
PSLLQ mmreg1, mmreg2
0Fh
F3h
11-xxx-xxx
short
meu
PSLLQ mmreg, mem64
0Fh
F3h
11-xxx-xxx
short
meu
PSLLQ mmreg, imm8
0Fh
73h
11-110-xxx
short
meu
PSRAW mmreg1, mmreg2
0Fh
E1h
11-xxx-xxx
short
meu
PSRAW mmreg, mem64
0Fh
E1h
11-xxx-xxx
short
meu
PSRAW mmreg, imm8
0Fh
71h
11-100-xxx
short
meu
PSRAD mmreg1, mmreg2
0Fh
E2h
11-xxx-xxx
short
meu
PSRAD mmreg, mem64
0Fh
E2h
11-xxx-xxx
short
meu
PSRAD mmreg, imm8
0Fh
72h
11-100-xxx
short
meu
PSRAQ mmreg1, mmreg2
0Fh
E3h
11-xxx-xxx
short
meu
PSRAQ mmreg, mem64
0Fh
E3h
11-xxx-xxx
short
meu
PSRAQ mmreg, imm8
0Fh
73h
11-100-xxx
short
meu
PSRLW mmreg1, mmreg2
0Fh
D1h
11-xxx-xxx
short
meu
PSRLW mmreg, mem64
0Fh
D1h
11-xxx-xxx
short
meu
PSRLW mmreg, imm8
0Fh
71h
11-010-xxx
short
meu
PSRLD mmreg1, mmreg2
0Fh
D2h
11-xxx-xxx
short
meu
PSRLD mmreg, mem64
0Fh
D2h
11-xxx-xxx
short
meu
PSRLD mmreg, imm8
0Fh
72h
11-010-xxx
short
meu
PSRLQ mmreg1, mmreg2
0Fh
D3h
11-xxx-xxx
short
meu
PSRLQ mmreg, mem64
0Fh
D3h
11-xxx-xxx
short
meu
Note
Note:
*
74
Bits 2, 1, and 0 of the modR/M byte select the integer register.
Software Environment
Chapter 3
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 12. MMX™ Instructions (continued)
Instruction Mnemonic
Prefix First
Byte(s) Byte
ModR/M
Byte
Decode
Type
RISC86®
Opcodes
PSRLQ mmreg, imm8
0Fh
73h
11-010-xxx
short
meu
PSUBB mmreg1, mmreg2
0Fh
F8h
11-xxx-xxx
short
meu
PSUBB mmreg, mem64
0Fh
F8h
mm-xxx-xxx
short
mload, meu
PSUBD mmreg1, mmreg2
0Fh
FAh
11-xxx-xxx
short
meu
PSUBD mmreg, mem64
0Fh
FAh
mm-xxx-xxx
short
mload, meu
PSUBSB mmreg1, mmreg2
0Fh
E8h
11-xxx-xxx
short
meu
PSUBSB mmreg, mem64
0Fh
E8h
mm-xxx-xxx
short
mload, meu
PSUBSW mmreg1, mmreg2
0Fh
E9h
11-xxx-xxx
short
meu
PSUBSW mmreg, mem64
0Fh
E9h
mm-xxx-xxx
short
mload, meu
PSUBUSB mmreg1, mmreg2
0Fh
D8h
11-xxx-xxx
short
meu
PSUBUSB mmreg, mem64
0Fh
D8h
mm-xxx-xxx
short
mload, meu
PSUBUSW mmreg1, mmreg2
0Fh
D9h
11-xxx-xxx
short
meu
PSUBUSW mmreg, mem64
0Fh
D9h
mm-xxx-xxx
short
mload, meu
PSUBW mmreg1, mmreg2
0Fh
F9h
11-xxx-xxx
short
meu
PSUBW mmreg, mem64
0Fh
F9h
mm-xxx-xxx
short
mload, meu
PUNPCKHBW mmreg1, mmreg2
0Fh
68h
11-xxx-xxx
short
meu
PUNPCKHBW mmreg, mem64
0Fh
68h
mm-xxx-xxx
short
mload, meu
PUNPCKHWD mmreg1, mmreg2
0Fh
69h
11-xxx-xxx
short
meu
PUNPCKHWD mmreg, mem64
0Fh
69h
mm-xxx-xxx
short
mload, meu
PUNPCKHDQ mmreg1, mmreg2
0Fh
6Ah
11-xxx-xxx
short
meu
PUNPCKHDQ mmreg, mem64
0Fh
6Ah
mm-xxx-xxx
short
mload, meu
PUNPCKLBW mmreg1, mmreg2
0Fh
60h
11-xxx-xxx
short
meu
PUNPCKLBW mmreg, mem64
0Fh
60h
mm-xxx-xxx
short
mload, meu
PUNPCKLWD mmreg1, mmreg2
0Fh
61h
11-xxx-xxx
short
meu
PUNPCKLWD mmreg, mem64
0Fh
61h
mm-xxx-xxx
short
mload, meu
PUNPCKLDQ mmreg1, mmreg2
0Fh
62h
11-xxx-xxx
short
meu
PUNPCKLDQ mmreg, mem64
0Fh
62h
mm-xxx-xxx
short
mload, meu
PXOR mmreg1, mmreg2
0Fh
EFh
11-xxx-xxx
short
meu
PXOR mmreg, mem64
0Fh
EFh
mm-xxx-xxx
short
mload, meu
Note
Note:
*
Bits 2, 1, and 0 of the modR/M byte select the integer register.
Chapter 3
Software Environment
75
Preliminary Information
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Software Environment
Chapter 3
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4
Logic Symbol Diagram
Voltage Detection
Clock
CLK
Bus
Arbitration
Address
and
Address
Parity
Cycle
Definition
and
Control
Cache
Control
VCC2DET
BF[2:0]
AHOLD
BOFF#
BREQ
HLDA
HOLD
A20M#
A[31:3]
AP
ADS#
ADSC#
APCHK#
BE[7:0]#
AMD-K6®
D/C#
EWBE#
LOCK#
M/IO#
NA#
SCYC
W/R#
Processor
CACHE#
KEN#
PCD
PWT
WB/WT#
TCK
TDI
TDO
BRDY#
BRDYC#
D[63:0]
DP[7:0]
PCHK#
Data
and
Data
Parity
EADS#
HIT#
HITM#
INV
Inquire
Cycles
FERR#
IGNNE#
Floating-Point
Error Handling
FLUSH#
INIT
INTR
NMI
RESET
SMI#
SMIACT#
STPCLK#
External
Interrupts,
SMM, Reset and
Initialization
TMS TRST#
JTAG Test
Chapter 4
Logic Symbol Diagram
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Logic Symbol Diagram
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5
5.1
Signal Descriptions
A20M# (Address Bit 20 Mask)
Input
Summary
A20M# is used to simulate the behavior of the 8086 when
running in Real mode. The assertion of A20M # causes the
processor to force bit 20 of the physical address to 0 prior to
accessing the cache or driving out a memory bus cycle. The
clearing of address bit 20 maps addresses that wrap above 1
Mbyte to addresses below 1 Mbyte.
Sampled
The processor samples A20M # as a level-sensitive input on
every clock edge. The system logic can drive the signal either
s y n ch ro n o u s ly o r a s y n ch ro n o u s ly. I f i t i s a s s e r t e d
asynchronously, it must be asserted for a minimum pulse width
of two clocks.
The following list explains the effects of the processor sampling
A20M# asserted under various conditions:
■
■
■
■
■
Chapter 5
Inquire cycles and writeback cycles are not affected by the
state of A20M#.
The assertion of A20M# in System Management Mode
(SMM) is ignored.
When A20M# is sampled asserted in Protected mode, it
causes unpredictable processor operation. A20M# is only
defined in Real mode.
To ensure that A20M# is recognized before the first ADS#
occurs following the negation of RESET, A20M# must be
sampled asserted on the same clock edge that RESET is
sampled negated or on one of the two subsequent clock
edges.
To ensure A20M# is recognized before the execution of an
instruction, a serializing instruction must be executed
between the instruction that asserts A20M# and the
targeted instruction.
Signal Descriptions
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A[31:3] (Address Bus)
A[31:5] Bidirectional, A[4:3] Output
Summary
A[31:3] contain the physical address for the current bus cycle.
The processor drives addresses on A[31:3] during memory and
I/O cycles, and cycle definition information during special bus
cycles. The processor samples addresses on A[31:5] during
inquire cycles.
Driven, Sampled, and
Floated
As Outputs: A[31:3] are driven valid off the same clock edge as
ADS # and remain in the same state until the clock edge on
which NA# or the last expected BRDY# of the cycle is sampled
asserted. A[31:3] are driven during memory cycles, I/O cycles,
special bus cycles, and interrupt acknowledge cycles. The
processor continues to drive the address bus while the bus is
idle.
As Inputs: The processor samples A[31:5] during inquire cycles
on the clock edge on which EADS# is sampled asserted. Even
though A4 and A3 are not used during the inquire cycle, they
must be driven to a valid state and must meet the same timings
as A[31:5].
A[31:3] are floated off the clock edge that AHOLD or BOFF# is
sampled asserted and off the clock edge that the processor
asserts HLDA in recognition of HOLD.
The processor resumes driving A[31:3] off the clock edge on
which the processor samples AHOLD or BOFF# negated and off
the clock edge on which the processor negates HLDA.
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5.3
ADS# (Address Strobe)
Output
Summary
The assertion of ADS # indicates the beginning of a new bus
cycle. The address bus and all cycle definition signals
corresponding to this bus cycle are driven valid off the same
clock edge as ADS#.
Driven and Floated
ADS # is asserted for one clock at the beginning of each bus
cycle. For non-pipelined cycles, ADS# can be asserted as early
as the clock edge after the clock edge on which the last
expected BRDY# of the cycle is sampled asserted, resulting in a
single idle state between cycles. For pipelined cycles if the
processor is prepared to start a new cycle, ADS# can be asserted
as early as one clock edge after NA# is sampled asserted.
If AHOLD is sampled asserted, ADS# is only driven in order to
perform a writeback cycle due to an inquire cycle that hits a
modified cache line.
The processor floats ADS # off the clock edge that BOFF # is
sampled asserted and off the clock edge that the processor
asserts HLDA in recognition of HOLD.
5.4
ADSC# (Address Strobe Copy)
Output
Summary
Chapter 5
ADSC # has the identical function and timing as ADS#. In the
event ADS# becomes too heavily loaded due to a large fanout in
a system, ADSC # can be used to split the load across two
outputs, which improves timing.
Signal Descriptions
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AHOLD (Address Hold)
Input
Summary
AHOLD can be asserted by the system to initiate one or more
inquire cycles. To allow the system to drive the address bus
during an inquire cycle, the processor floats A[31:3] and AP off
the clock edge on which AHOLD is sampled asserted. The data
bus and all other control and status signals remain under the
control of the processor and are not floated. This allows a bus
cycle that is in progress when AHOLD is sampled asserted to
continue to completion. The processor resumes driving the
address bus off the clock edge on which AHOLD is sampled
negated.
If AHOLD is sampled asserted, ADS# is only asserted in order
to perform a writeback cycle due to an inquire cycle that hits a
modified cache line.
Sampled
82
The processor samples AHOLD on every clock edge. AHOLD is
recognized while INIT and RESET are sampled asserted.
Signal Descriptions
Chapter 5
Preliminary Information
AMD-K6® Processor Data Sheet
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5.6
AP (Address Parity)
Bidirectional
Summary
AP contains the even parity bit for cache line addresses driven
and sampled on A[31:5]. Even parity means that the total
number of 1 bits on AP and A[31:5] is even. (A4 and A3 are not
used for the generation or checking of address parity because
these bits are not required to address a cache line.) AP is driven
by the processor during processor-initiated cycles and is
sampled by the processor during inquire cycles. If AP does not
reflect even parity during an inquire cycle, the processor
asserts APCHK # to indicate an address bus parity check. The
processor does not take an internal exception as the result of
detecting an address bus parity check, and system logic must
respond appropriately to the assertion of this signal.
Driven, Sampled, and
Floated
As an Output: The processor drives AP valid off the clock edge
on which ADS# is asserted until the clock edge on which NA# or
the last expected BRDY# of the cycle is sampled asserted. AP is
driven during memory cycles, I/O cycles, special bus cycles, and
interrupt acknowledge cycles. The processor continues to drive
AP while the bus is idle.
As an Input: The processor samples AP during inquire cycles on
the clock edge on which EADS# is sampled asserted.
The processor floats AP off the clock edge that AHOLD or
BOFF # is sampled asserted and off the clock edge that the
processor asserts HLDA in recognition of HOLD.
The processor resumes driving AP off the clock edge on which
the processor samples AHOLD or BOFF # negated and off the
clock edge on which the processor negates HLDA.
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APCHK# (Address Parity Check)
Output
Summary
If the processor detects an address parity error during an
inquire cycle, APCHK# is asserted for one clock. The processor
does not take an internal exception as the result of detecting an
address bus parity check, and system logic must respond
appropriately to the assertion of this signal.
The processor ensures that APCHK # does not glitch, enabling
the signal to be used as a clocking source for system logic.
Driven
APCHK# is driven valid the clock edge after the clock edge on
which the processor samples EADS# asserted. It is negated off
the next clock edge.
APCHK# is always driven except in Tri-State Test mode.
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5.8
BE[7:0]# (Byte Enables)
Output
Summary
BE[7:0]# are used by the processor to indicate the valid data
bytes during a write cycle and the requested data bytes during
a read cycle. The byte enables can be used to derive address bits
A[2:0], which are not physically part of the processor’s address
bus. The processor checks and generates valid data parity for
the data bytes that are valid as defined by the byte enables. The
eight byte enables correspond to the eight bytes of the data bus
as follows:
■
■
■
■
BE7#: D[63:56]
BE6#: D[55:48]
BE5#: D[47:40]
BE4#: D[39:32]
■
■
■
■
BE3#: D[31:24]
BE2#: D[23:16]
BE1#: D[15:8]
BE0#: D[7:0]
The processor expects data to be driven by the system logic on
all eight bytes of the data bus during a burst cache-line read
cycle, independent of the byte enables that are asserted.
The byte enables are also used to distinguish between special
bus cycles as defined in Table 19 on page 119.
Driven and Floated
BE[7:0]# are driven off the same clock edge as ADS # and
remain in the same state until the clock edge on which NA# or
the last expected BRDY # of the cycle is sampled asserted.
BE[7:0]# are driven during memory cycles, I/O cycles, special
bus cycles, and interrupt acknowledge cycles.
The processor floats BE[7:0]# off the clock edge that BOFF# is
sampled asserted and off the clock edge that the processor
asserts HLDA in recognition of HOLD. Unlike the address bus,
BE[7:0]# are not floated in response to AHOLD.
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BF[2:0] (Bus Frequency)
Inputs, Internal Pullups
Summary
BF[2:0] determine the internal operating frequency of the
processor. The frequency of the CLK input signal is multiplied
internally by a ratio determined by the state of these signals as
defined in Table 13. BF[2:0] have weak internal pullups and
default to the 3.5 multiplier if left unconnected.
Table 13. Processor-to-Bus Clock Ratios
Sampled
86
State of BF[2:0] Inputs
Processor-Clock to Bus-Clock Ratio
100b
2.5x
101b
3.0x
110b
2.0x
111b
3.5x
000b
4.5x
001b
5.0x
010b
4.0x
011b
5.5x
BF[2:0] are sampled during the falling transition of RESET.
They must meet a minimum setup time of 1.0 ms and a
minimum hold time of two clocks relative to the negation of
RESET.
Signal Descriptions
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5.10
BOFF# (Backoff)
Input
Summary
If BOFF # is sampled asserted, the processor unconditionally
aborts any cycles in progress and transitions to a bus hold state
by floating the following signals: A[31:3], ADS #, ADSC #, AP,
BE[7:0]#, CACHE #, D[63:0], D/C #, DP[7:0], LOCK #, M/IO #,
PCD, PWT, SCYC, and W/R#. These signals remain floated until
BOFF# is sampled negated. This allows an alternate bus master
or the system to control the bus.
When BOFF# is sampled negated, any processor cycle that was
aborted due to the assertion of BOFF # is restarted from the
beginning of the cycle, regardless of the number of transfers
that were completed. If BOFF# is sampled asserted on the same
clock edge as BRDY# of a bus cycle of any length, then BOFF#
takes precedence over the BRDY #. In this case, the cycle is
aborted and restarted after BOFF# is sampled negated.
Sampled
BOFF# is sampled on every clock edge. The processor floats its
bus signals off the clock edge on which BOFF # is sampled
asserted. These signals remain floated until the clock edge on
which BOFF# is sampled negated.
BOFF # is recognized while INIT and RESET are sampled
asserted.
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BRDY# (Burst Ready)
Input, Internal Pullup
Summary
BRDY# is asserted to the processor by system logic to indicate
either that the data bus is being driven with valid data during a
read cycle or that the data bus has been latched during a write
cycle. If necessary, the system logic can insert bus cycle wait
states by negating BRDY# until it is ready to continue the data
transfer. BRDY # is also used to indicate the completion of
special bus cycles.
Sampled
BRDY# is sampled every clock edge within a bus cycle starting
with the clock edge after the clock edge that negates ADS #.
BRDY# is ignored while the bus is idle. The processor samples
the following inputs on the clock edge on which BRDY # is
sampled asserted: D[63:0], DP[7:0], and KEN # during read
cycles, EWBE# during write cycles, and WB/WT# during read
and write cycles. If NA # is sampled asserted prior to BRDY #,
then KEN # and WB/WT # are sampled on the clock edge on
which NA# is sampled asserted.
The number of times the processor expects to sample BRDY #
asserted depends on the type of bus cycle, as follows:
■
■
One time for a single-transfer cycle, a special bus cycle, or
each of two cycles in an interrupt acknowledge sequence
Four times for a burst cycle (once for each data transfer)
BRDY # can be held asserted for four consecutive clocks
throughout the four transfers of the burst, or it can be negated
to insert wait states.
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5.12
BRDYC# (Burst Ready Copy)
Input, Internal Pullup
Summary
BRDYC # has the identical function as BRDY #. In the event
BRDY # becomes too heavily loaded due to a large fanout or
loading in a system, BRDYC # can be used to reduce this
loading, which improves timing.
In addition, BRDYC # is sampled when RESET is negated to
configure the drive strength of A[20:3], ADS #, HITM #, and
W/R #. If BRDYC# is 0 during the falling transition of RESET,
these particular outputs are configured using higher drive
strengths than the standard strength. If BRDYC# is 1 during the
falling transition of RESET, the standard strength is selected.
Sampled
BRDYC# is sampled every clock edge within a bus cycle starting
with the clock edge after the clock edge that negates ADS#.
BRDYC# is also sampled during the falling transition of RESET.
If RESET is driven synchronously, BRDYC # must meet the
specified hold time relative to the negation of RESET. If
RESET is driven asynchronously, the minimum setup and hold
time for BRDYC # relative to the negation of RESET is two
clocks.
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BREQ (Bus Request)
Output
Summary
BREQ is asserted by the processor to request the bus in order to
complete an internally pending bus cycle. The system logic can
use BREQ to arbitrate among the bus participants. If the
processor does not own the bus, BREQ is asserted until the
processor gains access to the bus in order to begin the pending
cycle or until the processor no longer needs to run the pending
cycle. If the processor currently owns the bus, BREQ is asserted
with ADS#. The processor asserts BREQ for each assertion of
ADS# but does not necessarily assert ADS# for each assertion of
BREQ.
Driven
BREQ is asserted off the same clock edge on which ADS # is
asserted. BREQ can also be asserted off any clock edge,
independent of the assertion of ADS#. BREQ can be negated
one clock edge after it is asserted.
The processor always drives BREQ except in Tri-State Test
mode.
5.14
CACHE# (Cacheable Access)
Output
Summary
For reads, CACHE# is asserted to indicate the cacheability of
the current bus cycle. In addition, if the processor samples
KEN # assert ed, which indicates t he driven address is
cacheable, the cycle is a 32-byte burst read cycle. For write
cycles, CACHE# is asserted to indicate the current bus cycle is a
modified cache-line writeback. KEN # is ignored during
writebacks. If CACHE# is not asserted, or if KEN # is sampled
negated during a read cycle, the cycle is not cacheable and
defaults to a single-transfer cycle.
Driven and Floated
CACHE# is driven off the same clock edge as ADS# and remains
in the same state until the clock edge on which NA# or the last
expected BRDY# of the cycle is sampled asserted.
CACHE # is floated off the clock edge that BOFF # is sampled
asserted and off the clock edge that the processor asserts HLDA
in recognition of HOLD.
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5.15
CLK (Clock)
Input
Summary
The CLK signal is the bus clock for the processor and is the
reference for all signal timings under normal operation (except
for TDI, TDO, TMS, and TRST#). BF[2:0] determine the internal
frequency multiplier applied to CLK to obtain the processor’s
core operating frequency. (See “BF[2:0] (Bus Frequency)” on
page 86 for a list of the processor-to-bus clock ratios.)
Sampled
The CLK signal must be stable a minimum of 1.0 ms prior to the
negation of RESET to ensure the proper operation of the
processor. See “CLK Switching Characteristics” on page 241 for
details regarding the CLK specifications.
5.16
D/C# (Data/Code)
Output
Summary
The processor drives D/C # during a memory bus cycle to
indicate whether it is addressing data or executable code. D/C#
is also used to define other bus cycles, including interrupt
acknowledge and special cycles. (See Table 19 on page 119 for
more details.)
Driven and Floated
D/C# is driven off the same clock edge as ADS# and remains in
the same state until the clock edge on which NA # or the last
expected BRDY # of the cycle is sampled asserted. D/C # is
driven during memory cycles, I/O cycles, special bus cycles, and
interrupt acknowledge cycles.
D/C # is floated off the clock edge that BOFF # is sampled
asserted and off the clock edge that the processor asserts HLDA
in recognition of HOLD.
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D[63:0] (Data Bus)
Bidirectional
Summary
D[63:0] represent the processor’s 64-bit data bus. Each of the
eight bytes of data that comprise this bus is qualified as valid
by its corresponding byte enable. (See “BE[7:0]# (Byte
Enables)” on page 85.)
Driven, Sampled, and
Floated
As Outputs: For single-transfer write cycles, the processor drives
D[63:0] with valid data one clock edge after the clock edge on
which ADS# is asserted and D[63:0] remain in the same state
until the clock edge on which BRDY# is sampled asserted. If the
cycle is a writeback—in which case four, 8-byte transfers
occur—D[63:0] are driven one clock edge after the clock edge
on which ADS# is asserted and are subsequently changed off
the clock edge on which each BRDY# assertion of the burst
cycle is sampled.
If the assertion of ADS# represents a pipelined write cycle that
follows a read cycle, the processor does not drive D[63:0] until it
is certain that contention on the data bus will not occur. In this
case, D[63:0] are driven the clock edge after the last expected
BRDY# of the previous cycle is sampled asserted.
As Inputs: During read cycles, the processor samples D[63:0] on
the clock edge on which BRDY# is sampled asserted.
The processor always floats D[63:0] except when they are being
driven during a write cycle as described above. In addition,
D[63:0] are floated off the clock edge that BOFF # is sampled
asserted and off the clock edge that the processor asserts
HLDA in recognition of HOLD.
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5.18
DP[7:0] (Data Parity)
Bidirectional
Summary
DP[7:0] are even parity bits for each valid byte of data — as
defined by BE[7:0]#—driven and sampled on the D[63:0] data
bus. (Even parity means that the total number of 1 bits within
each byte of data and its respective data parity bit is even.)
DP[7:0] are driven by the processor during write cycles and
sampled by the processor during read cycles. If the processor
detects bad parity on any valid byte of data during a read cycle,
PCHK# is asserted for one clock beginning the clock edge after
BRDY # is sampled asserted. The processor does not take an
internal exception as the result of detecting a data parity
check, and system logic must respond appropriately to the
assertion of this signal.
The eight data parity bits correspond to the eight bytes of the
data bus as follows:
■
■
■
■
DP7: D[63:56]
DP6: D[55:48]
DP5: D[47:40]
DP4: D[39:32]
■
■
■
■
DP3: D[31:24]
DP2: D[23:16]
DP1: D[15:8]
DP0: D[7:0]
For systems that do not support data parity, DP[7:0] should be
connected to VCC3 through pullup resistors.
Driven, Sampled, and
Floated
As Outputs: For single-transfer write cycles, the processor drives
DP[7:0] with valid parity one clock edge after the clock edge on
which ADS# is asserted and DP[7:0] remain in the same state
until the clock edge on which BRDY# is sampled asserted. If the
cycle is a writeback, DP[7:0] are driven one clock edge after the
clock edge on which ADS# is asserted and are subsequently
changed off the clock edge on which each BRDY# assertion of
the burst cycle is sampled.
As Inputs: During read cycles, the processor samples DP[7:0] on
the clock edge BRDY# is sampled asserted.
The processor always floats DP[7:0] except when they are being
driven during a write cycle as described above. In addition,
DP[7:0] are floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts
HLDA in recognition of HOLD.
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EADS# (External Address Strobe)
Input
Summary
System logic asserts EADS # during a cache inquire cycle to
indicate that the address bus contains a valid address. EADS#
can only be driven after the system logic has taken control of
the address bus by asserting AHOLD or BOFF# or by receiving
HLDA. The processor responds to the sampling of EADS# and
the address bus by driving HIT#, which indicates if the inquired
cache line exists in the processor’s cache, and HITM#, which
indicates if it is in the modified state.
Sampled
If AHOLD or BOFF# is asserted by the system logic in order to
execute a cache inquire cycle, the processor begins sampling
EADS # two clock edges after AHOLD or BOFF # is sampled
asserted. If the system logic asserts HOLD in order to execute a
cache inquire cycle, the processor begins sampling EADS# two
clock edges after the clock edge HLDA is asserted by the
processor.
EADS# is ignored during the following conditions:
■
■
■
■
94
One clock edge after the clock edge on which EADS# is
sampled asserted
Two clock edges after the clock edge on which ADS# is
asserted
When the processor is driving the address bus
When the processor asserts HITM#
Signal Descriptions
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5.20
EWBE# (External Write Buffer Empty)
Input
Summary
The system logic can negate EWBE# to the processor to indicate
that its external write buffers are full and that additional data
cannot be stored at this time. This causes the processor to delay
the following activities until EWBE# is sampled asserted:
■
The commitment of write hit cycles to cache lines in the
modified state or exclusive state in the processor’s cache
■
The decode and execution of an instruction that follows a
currently-executing serializing instruction
The assertion or negation of SMIACT#
The entering of the Halt state and the Stop Grant state
■
■
Negating EWBE# does not prevent the completion of any type
of cycle that is currently in progress.
Sampled
The processor samples EWBE# on each clock edge that BRDY#
is sampled asserted during all memory write cycles (except
writeback cycles), I/O write cycles, and special bus cycles.
If EWBE# is sampled negated, it is sampled on every clock edge
until it is asserted, and then it is ignored until BRDY # is
sampled asserted in the next write cycle or special cycle.
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FERR# (Floating-Point Error)
Output
Summary
The assertion of FERR # indicates the occurrence of an
unmasked floating-point exception resulting from the
execution of a floating-point instruction. This signal is provided
to allow the system logic to handle this exception in a manner
consistent with IBM-compatible PC/AT systems. See “Handling
Floating-Point Exceptions” on page 189 for a system logic
implementation that supports floating-point exceptions.
The state of the numeric error (NE) bit in CR0 does not affect
the FERR# signal.
The processor ensures that FERR# does not glitch, enabling the
signal to be used as a clocking source for system logic.
Driven
The processor asserts FERR # on the instruction boundary of
the next floating-point instruction, MMX instruction, or WAIT
instruction that occurs following the floating-point instruction
that caused the unmasked floating-point exception—that is,
FERR # is not asserted at the time the exception occurs. The
IGNNE# signal does not affect the assertion of FERR#.
FERR# is negated during the following conditions:
■
■
■
Following the successful execution of the floating-point
instructions FCLEX, FINIT, FSAVE, and FSTENV
Under certain circumstances, following the successful
execution of the floating-point instructions FLDCW,
FLDENV, and FRSTOR, which load the floating-point status
word or the floating-point control word
Following the falling transition of RESET
FERR# is always driven except in Tri-State Test mode.
See “IGNNE# (Ignore Numeric Exception)” on page 100 for
more details on floating-point exceptions.
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5.22
FLUSH# (Cache Flush)
Input
Summary
In response to sampling FLUSH# asserted, the processor writes
back any data cache lines that are in the modified state,
invalidates all lines in the instruction and data caches, and then
executes a flush acknowledge special cycle. (See Table 19 on
page 119 for the bus definition of special cycles.)
In addition, FLUSH # is sampled when RESET is negated to
determine if the processor enters Tri-State Test mode. If
FLUSH # is 0 during the falling transition of RESET, the
processor enters Tri-State Test mode instead of performing the
normal RESET functions.
Sampled
FLUSH # is sampled and latched as a falling edge-sensitive
signal. During normal operation (not RESET), FLUSH # is
sampled on every clock edge but is not recognized until the next
instruction boundary. If FLUSH# is asserted synchronously, it
can be asserted for a minimum of one clock. If FLUSH # is
asserted asynchronously, it must have been negated for a
minimum of two clocks, followed by an assertion of a minimum
of two clocks.
FLUSH# is also sampled during the falling transition of RESET.
If RESET and FLUSH# are driven synchronously, FLUSH# is
sampled on the clock edge prior to the clock edge on which
RESET is sampled negated. If RESET is driven asynchronously,
the minimum setup and hold time for FLUSH#, relative to the
negation of RESET, is two clocks.
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HIT# (Inquire Cycle Hit)
Output
Summary
The processor asserts HIT# during an inquire cycle to indicate
that the cache line is valid within the processor’s instruction or
data cache (also known as a cache hit). The cache line can be in
the modified, exclusive, or shared state.
Driven
HIT # is always driven — except in Tri-State Test mode — and
only changes state the clock edge after the clock edge on which
EADS# is sampled asserted. It is driven in the same state until
the next inquire cycle.
5.24
HITM# (Inquire Cycle Hit To Modified Line)
Output
Summary
The processor asserts HITM # during an inquire cycle to
indicate that the cache line exists in the processor’s data cache
in the modified state. The processor performs a writeback cycle
as a result of this cache hit. If an inquire cycle hits a cache line
that is currently being written back, the processor asserts
HITM # but does not execute another writeback cycle. The
system logic must not expect the processor to assert ADS# each
time HITM# is asserted.
Driven
HITM# is always driven—except in Tri-State Test mode—and,
in particular, is driven to represent the result of an inquire cycle
the clock edge after the clock edge on which EADS# is sampled
asserted. If HITM # is negated in response to the inquire
address, it remains negated until the next inquire cycle. If
HITM# is asserted in response to the inquire address, it remains
asserted throughout the writeback cycle and is negated one
clock edge after the last BRDY # of the writeback is sampled
asserted.
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5.25
HLDA (Hold Acknowledge)
Output
Summary
When HOLD is sampled asserted, the processor completes the
current bus cycles, floats the processor bus, and asserts HLDA
in an acknowledgment that these events have been completed.
The processor does not assert HLDA until the completion of a
locked sequence of cycles. While HLDA is asserted, another bus
master can drive cycles on the bus, including inquire cycles to
the processor. The following signals are floated when HLDA is
asserted: A[31:3], ADS #, ADSC #, AP, BE[7:0]#, CACHE #,
D[63:0], D/C #, DP[7:0], LOCK #, M/IO #, PCD, PWT, SCYC, and
W/R#.
The processor ensures that HLDA does not glitch.
Driven
HLDA is always driven except in Tri-State Test mode. If a
processor cycle is in progress while HOLD is sampled asserted,
HLDA is asserted one clock edge after the last BRDY # of the
cycle is sampled asserted. If the bus is idle, HLDA is asserted
one clock edge after HOLD is sampled asserted. HLDA is
negated one clock edge after the clock edge on which HOLD is
sampled negated.
The assertion of HLDA is independent of the sampled state of
BOFF#.
The processor floats the bus every clock in which HLDA is
asserted.
5.26
HOLD (Bus Hold Request)
Input
Summary
The system logic can assert HOLD to gain control of the
processor’s bus. When HOLD is sampled asserted, the processor
completes the current bus cycles, floats the processor bus, and
asserts HLDA in an acknowledgment that these events have
been completed.
Sampled
The processor samples HOLD on every clock edge. If a
processor cycle is in progress while HOLD is sampled asserted,
HLDA is asserted one clock edge after the last BRDY # of the
cycle is sampled asserted. If the bus is idle, HLDA is asserted
one clock edge after HOLD is sampled asserted. HOLD is
recognized while INIT and RESET are sampled asserted.
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IGNNE# (Ignore Numeric Exception)
Input
Summary
IGNNE#, in conjunction with the numeric error (NE) bit in CR0,
is used by the system logic to control the effect of an unmasked
floating-point exception on a previous floating-point instruction
during the execution of a floating-point instruction, MMX
instruction, or the WAIT instruction—hereafter referred to as
the target instruction.
If an unmasked floating-point exception is pending and the
target instruction is considered error-sensitive, then the
relationship between NE and IGNNE# is as follows:
■
If NE = 0, then:
• If IGNNE# is sampled asserted, the processor ignores the
floating-point exception and continues with the
execution of the target instruction.
• If IGNNE# is sampled negated, the processor waits until
it samples IGNNE#, INTR, SMI#, NMI, or INIT asserted.
If IGNNE# is sampled asserted while waiting, the
processor ignores the floating-point exception and
continues with the execution of the target instruction.
If INTR, SMI#, NMI, or INIT is sampled asserted while
waiting, the processor handles its assertion
appropriately.
■
If NE = 1, the processor invokes the INT 10h exception
handler.
If an unmasked floating-point exception is pending and the
target instruction is considered error-insensitive, then the
processor ignores the floating-point exception and continues
with the execution of the target instruction.
FERR # is not affected by the state of the NE bit or IGNNE #.
FERR # is always asserted at the instruction boundary of the
target instruction that follows the floating-point instruction
that caused the unmasked floating-point exception.
This signal is provided to allow the system logic to handle
exceptions in a manner consistent with IBM-compatible PC/AT
systems.
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Sampled
5.28
The processor samples IGNNE # as a level-sensitive input on
every clock edge. The system logic can drive the signal either
s y n ch ro n o u s ly o r a s y n ch ro n o u s ly. I f i t i s a s s e r t e d
asynchronously, it must be asserted for a minimum pulse width
of two clocks.
INIT (Initialization)
Input
Summary
The assertion of INIT causes the processor to empty its
pipelines, to initialize most of its internal state, and to branch
to address FFFF_FFF0h—the same instruction execution
starting point used after RESET. Unlike RESET, the processor
preserves the contents of its caches, the floating-point state, the
MMX state, Model-Specific Registers, the CD and NW bits of
the CR0 register, and other specific internal resources.
INIT can be used as an accelerator for 80286 code that requires
a reset to exit from Protected mode back to Real mode.
Sampled
INIT is sampled and latched as a rising edge-sensitive signal.
INIT is sampled on every clock edge but is not recognized until
the next instruction boundary. During an I/O write cycle, it must
be sampled asserted a minimum of three clock edges before
BRDY # is sampled asserted if it is to be recognized on the
boundary between the I/O write instruction and the following
instruction.
If INIT is asserted synchronously, it can be asserted for a
minimum of one clock. If it is asserted asynchronously, it must
have been negated for a minimum of two clocks, followed by an
assertion of a minimum of two clocks.
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INTR (Maskable Interrupt)
Input
Summary
INTR is the system’s maskable interrupt input to the processor.
When the processor samples and recognizes INTR asserted, the
processor executes a pair of interrupt acknowledge bus cycles
and then jumps to the interrupt service routine specified by the
interrupt number that was returned during the interrupt
acknowledge sequence. The processor only recognizes INTR if
the interrupt flag (IF) in the EFLAGS register equals 1.
Sampled
The processor samples INTR as a level-sensitive input on every
clock edge, but the interrupt request is not recognized until the
next instruction boundary. The system logic can drive INTR
either synchronously or asynchronously. If it is asserted
asynchronously, it must be asserted for a minimum pulse width
of two clocks. In order to be recognized, INTR must remain
asserted until an interrupt acknowledge sequence is complete.
5.30
INV (Invalidation Request)
Input
Summary
During an inquire cycle, the state of INV determines whether
an addressed cache line that is found in the processor’s
instruction or data cache transitions to the invalid state or the
shared state.
If INV is sampled asserted during an inquire cycle, the
processor transitions the cache line (if found) to the invalid
state, regardless of its previous state. If INV is sampled negated
during an inquire cycle, the processor transitions the cache line
(if found) to the shared state. In either case, if the cache line is
found in the modified state, the processor writes it back to
memory before changing its state.
Sampled
102
INV is sampled on the clock edge on which EADS# is sampled
asserted.
Signal Descriptions
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5.31
KEN# (Cache Enable)
Input
Summary
If KEN # is sampled asserted, it indicates that the address
presented by the processor is cacheable. If KEN # is sampled
asserted and the processor intends to perform a cache-line fill
(signified by the assertion of CACHE#), the processor executes
a 32-byte burst read cycle and expects to sample BRDY #
asserted a total of four times. If KEN # is sampled negated
during a read cycle, a single-transfer cycle is executed and the
processor does not cache the data. For write cycles, CACHE# is
asserted to indicate the current bus cycle is a modified
cache-line writeback. KEN# is ignored during writebacks.
If PCD is asserted during a bus cycle, the processor does not
cache any data read during that cycle, regardless of the state of
KEN#. (See “PCD (Page Cache Disable)” on page 107 for more
details.)
If the processor has sampled the state of KEN# during a cycle,
and that cycle is aborted due to the sampling of BOFF #
asserted, the system logic must ensure that KEN# is sampled in
the same state when the processor restarts the aborted cycle.
Sampled
Chapter 5
KEN# is sampled on the clock edge on which the first BRDY# or
NA # of a read cycle is sampled asserted. If the read cycle is a
burst, KEN # is ignored during the last three assertions of
BRDY #. KEN # is sampled during read cycles only when
CACHE# is asserted.
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LOCK# (Bus Lock)
Output
Summary
The processor asserts LOCK# during a sequence of bus cycles to
ensure that the cycles are completed without allowing other bus
masters to intervene. Locked operations consist of two to five
bus cycles. LOCK# is asserted during the following operations:
■
An interrupt acknowledge sequence
Descriptor Table accesses
Page Directory and Page Table accesses
XCHG instruction
■
An instruction with an allowable LOCK prefix
■
■
■
In order to ensure that locked operations appear on the bus and
are visible to the entire system, any data operands addressed
during a locked cycle that reside in the processor’s cache are
flushed and invalidated from the cache prior to the locked
operation. If the cache line is in the modified state, it is written
back and invalidated prior to the locked operation. Likewise,
any data read during a locked operation is not cached.
The processor ensures that LOCK# does not glitch.
Driven and Floated
During a locked cycle, LOCK# is asserted off the same clock
edge on which ADS# is asserted and remains asserted until the
last BRDY# of the last bus cycle is sampled asserted. The
processor negates LOCK# for at least one clock between
consecutive sequences of locked operations to allow the system
logic to arbitrate for the bus.
LOCK# is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD. When LOCK# is floated due to BOFF#
sampled asserted, the system logic is responsible for preserving
the lock condition while LOCK# is in the high-impedance state.
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5.33
M/IO# (Memory or I/O)
Output
Summary
The processor drives M/IO# during a bus cycle to indicate
whether it is addressing the memory or I/O space. If M/IO# = 1,
the processor is addressing memory or a memory-mapped I/O
port as the result of an instruction fetch or an instruction that
loads or stores data. If M/IO# = 0, the processor is addressing an
I/O port during the execution of an I/O instruction. In addition,
M/IO# is used to define other bus cycles, including interrupt
acknowledge and special cycles. (See Table 19 on page 119 for
more details.)
Driven and Floated
M/IO# is driven off the same clock edge as ADS# and remains in
the same state until the clock edge on which NA# or the last
expected BRDY# of the cycle is sampled asserted. M/IO# is
driven during memory cycles, I/O cycles, special bus cycles, and
interrupt acknowledge cycles.
M/IO# is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD.
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NA# (Next Address)
Input
Summary
System logic asserts NA# to indicate to the processor that it is
ready to accept another bus cycle pipelined into the previous
bus cycle. ADS#, along with address and status signals, can be
asserted as early as one clock edge after NA# is sampled
asserted if the processor is prepared to start a new cycle.
Because the processor allows a maximum of two cycles to be in
progress at a time, the assertion of NA# is sampled while two
cycles are in progress but ADS# is not asserted until the
completion of the first cycle.
Sampled
NA# is sampled every clock edge during bus cycles, starting one
clock edge after the clock edge that negates ADS#, until the last
expected BRDY# of the last executed cycle is sampled asserted
(with the exception of the clock edge after the clock edge that
negates the ADS# for a second pending cycle). Because the
processor latches NA# when sampled, the system logic only
needs to assert NA# for one clock.
5.35
NMI (Non-Maskable Interrupt)
Input
Summary
When NMI is sampled asserted, the processor jumps to the
interrupt service routine defined by interrupt number 02h.
Unlike the INTR signal, software cannot mask the effect of NMI
if it is sampled asserted by the processor. However, NMI is
temporarily masked upon entering System Management Mode
(SMM). In addition, an interrupt acknowledge cycle is not
executed because the interrupt number is predefined.
If NMI is sampled asserted while the processor is executing the
interrupt service routine for a previous NMI, the subsequent
NMI remains pending until the completion of the execution of
the IRET instruction at the end of the interrupt service routine.
Sampled
106
NMI is sampled and latched as a rising edge-sensitive signal.
During normal operation, NMI is sampled on every clock edge
but is not recognized until the next instruction boundary. If it is
asserted synchronously, it can be asserted for a minimum of one
clock. If it is asserted asynchronously, it must have been
negated for a minimum of two clocks, followed by an assertion
of a minimum of two clocks.
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5.36
PCD (Page Cache Disable)
Output
Summary
The processor drives PCD to indicate the operating system’s
specification of cacheability for the page being addressed.
System logic can use PCD to control external caching. If PCD is
asserted, the addressed page is not cached. If PCD is negated,
the cacheability of the addressed page depends upon the state
of CACHE# and KEN#.
The state of PCD depends upon the processor’s operating mode
and the state of certain bits in its control registers and TLB as
follows:
■
■
Driven and Floated
In Real mode, or in Protected and Virtual-8086 modes while
paging is disabled (PG bit in CR0 set to 0):
PCD output = CD bit in CR0
In Protected and Virtual-8086 modes while caching is
enabled (CD bit in CR0 set to 0) and paging is enabled (PG
bit in CR0 set to 1):
• For accesses to I/O space, page directory entries, and
other non-paged accesses:
PCD output = PCD bit in CR3
• For accesses to 4-Kbyte page table entries or 4-Mbyte
pages:
PCD output = PCD bit in page directory entry
• For accesses to 4-Kbyte pages:
PCD output = PCD bit in page table entry
PCD is driven off the same clock edge as ADS# and remains in
the same state until the clock edge on which NA# or the last
expected BRDY# of the cycle is sampled asserted.
PCD is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD.
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PCHK# (Parity Check)
Output
Summary
The processor asserts PCHK# during read cycles if it detects an
even parity error on one or more valid bytes of D[63:0] during a
read cycle. (Even parity means that the total number of 1 bits
within each byte of data and its respective data parity bit is
even.) The processor checks data parity for the data bytes that
are valid, as defined by BE[7:0]#, the byte enables.
PCHK# is always driven but is only asserted for memory and I/O
re a d b u s cy c l es a n d t he se c o n d cy c l e of a n i n t e r ru p t
acknowledge sequence. PCHK# is not driven during any type of
write cycles or special bus cycles. The processor does not take
an internal exception as the result of detecting a data parity
error, and system logic must respond appropriately to the
assertion of this signal.
The processor ensures that PCHK# does not glitch, enabling the
signal to be used as a clocking source for system logic.
Driven
108
PCHK# is always driven except in Tri-State Test mode. For each
BRDY# returned to the processor during a read cycle with a
parity error detected on the data bus, PCHK# is asserted for
one clock, one clock edge after BRDY# is sampled asserted.
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5.38
PWT (Page Writethrough)
Output
Summary
The processor drives PWT to indicate the operating system’s
specification of the writeback state or writethrough state for
the page being addressed. PWT, together with WB/WT#,
specifies the data cache-line state during cacheable read misses
and write hits to shared cache lines. (See “WB/WT# (Writeback
or Writethrough)” on page 116 for more details.)
The state of PWT depends upon the processor’s operating mode
and the state of certain bits in its control registers and TLB as
follows:
■
■
Driven and Floated
In Real mode, or in Protected and Virtual-8086 modes while
paging is disabled (PG bit in CR0 set to 0):
PWT output = 0 (writeback state)
In Protected and Virtual-8086 modes while paging is
enabled (PG bit in CR0 set to 1):
• For accesses to I/O space, page directory entries, and
other non-paged accesses:
PWT output = PWT bit in CR3
• For accesses to 4-Kbyte page table entries or 4-Mbyte
pages:
PWT output = PWT bit in page directory entry
• For accesses to 4-Kbyte pages:
PWT output = PWT bit in page table entry
PWT is driven off the same clock edge as ADS# and remains in
the same state until the clock edge on which NA# or the last
expected BRDY# of the cycle is sampled asserted.
PWT is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD.
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RESET (Reset)
Input
Summary
When the processor samples RESET asserted, it immediately
flushes and initializes all internal resources and its internal
state including its pipelines and caches, the floating-point
state, the MMX state, and all registers, and then the processor
jumps to address FFFF_FFF0h to start instruction execution.
The signals BRDYC# and FLUSH# are sampled during the
falling transition of RESET to select the drive strength of
selected output signals and to invoke the Tri-State Test mode,
respectively. (See these signal descriptions for more details.)
Sampled
RESET is sampled as a level-sensitive input on every clock
edge. System logic can drive the signal either synchronously or
asynchronously.
During the initial power-on reset of the processor, RESET must
remain asserted for a minimum of 1.0 ms after CLK and VCC
reach specification before it is negated.
During a warm reset, while CLK and V CC are within their
specification, RESET must remain asserted for a minimum of
15 clocks prior to its negation.
5.40
Summary
RSVD (Reserved)
Reserved signals are a special class of pins that can be treated
in one of the following ways:
■
■
■
As no-connect (NC) pins, in which case these pins are left
unconnected
As pins connected to the system logic as defined by the
industry-standard Pentium interface (Socket 7)
Any combination of NC and Socket 7 pins
In any case, if the RSVD pins are treated accordingly, the
normal operation of the AMD-K6 processor is not adversely
affected in any manner.
See “Pin Designations” on page 269 for a list of the locations of
the RSVD pins.
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5.41
SCYC (Split Cycle)
Output
Summary
The processor asserts SCYC during misaligned, locked transfers
on the D[63:0] data bus. The processor generates additional bus
cycles to complete the transfer of misaligned data.
For purposes of bus cycles, the term aligned means:
■
Any 1-byte transfers
2-byte and 4-byte transfers that lie within 4-byte address
boundaries
■
8-byte transfers that lie within 8-byte address boundaries
■
Driven and Floated
SCYC is asserted off the same clock edge as ADS#, and negated
off the clock edge on which NA# or the last expected BRDY# of
the entire locked sequence is sampled asserted. SCYC is only
valid during locked memory cycles.
SCYC is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD.
5.42
SMI# (System Management Interrupt)
Input, Internal Pullup
Summary
The assertion of SMI# causes the processor to enter System
Management Mode (SMM). Upon recognizing SMI#, the
processor performs the following actions, in the order shown:
1. Flushes its instruction pipelines
2. Completes all pending and in-progress bus cycles
3. Acknowledges the interrupt by asserting SMIACT# after
sampling EWBE# asserted
4. Saves the internal processor state in SMM memory
5. Disables interrupts by clearing the interrupt flag (IF) in
EFLAGS and disables NMI interrupts
6. Jumps to the entry point of the SMM service routine at the
SMM base physical address which defaults to 0003_8000h in
SMM memory
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See “System Management Mode (SMM)” on page 193 for more
details regarding SMM.
Sampled
SMI# is sampled and latched as a falling edge-sensitive signal.
SMI# is sampled on every clock edge but is not recognized until
the next instruction boundary. If SMI# is to be recognized on
the instruction boundary associated with a BRDY#, it must be
sampled asserted a minimum of three clock edges before the
BRDY# is sampled asserted. If it is asserted synchronously, it
can be asserted for a minimum of one clock. If it is asserted
asynchronously, it must have been negated for a minimum of
two clocks followed by an assertion of a minimum of two clocks.
A second assertion of SMI# while in SMM is latched but is not
recognized until the SMM service routine is exited.
5.43
SMIACT# (System Management Interrupt Active)
Output
Summary
The processor acknowledges the assertion of SMI# with the
assertion of SMIACT# to indicate that the processor has
entered System Management Mode (SMM). The system logic
can use SMIACT# to enable SMM memory. See “SMI# (System
Management Interrupt)” on page 111 for more details.
See “System Management Mode (SMM)” on page 193 for more
details regarding SMM.
Driven
The processor asserts SMIACT# after the last BRDY# of the last
pending bus cycle is sampled asserted (including all pending
write cycles) and after EWBE# is sampled asserted. SMIACT#
remains asserted until after the last BRDY# of the last pending
bus cycle associated with exiting SMM is sampled asserted.
SMIACT# remains asserted during any flush, internal snoop, or
writeback cycle due to an inquire cycle.
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5.44
STPCLK# (Stop Clock)
Input, Internal Pullup
Summary
The assertion of STPCLK# causes the processor to enter the
Stop Grant state, during which the processor’s internal clock is
stopped. From the Stop Grant state, the processor can
subsequently transition to the Stop Clock state, in which the
bus clock CLK is stopped. Upon recognizing STPCLK#, the
processor performs the following actions, in the order shown:
1. Flushes its instruction pipelines
2. Completes all pending and in-progress bus cycles
3. Acknowledges the STPCLK# assertion by executing a Stop
Grant special bus cycle (see Table 19 on page 119)
4. Stops its internal clock after BRDY# of the Stop Grant
special bus cycle is sampled asserted and after EWBE# is
sampled asserted
5. Enters the Stop Clock state if the system logic stops the bus
clock CLK (optional)
See “Clock Control” on page 223 for more details regarding
clock control.
Sampled
STPCLK# is sampled as a level-sensitive input on every clock
edge but is not recognized until the next instruction boundary.
System logic can drive the signal either synchronously or
asynchronously. If it is asserted asynchronously, it must be
asserted for a minimum pulse width of two clocks.
STPCLK# must remain asserted until recognized, which is
indicated by the completion of the Stop Grant special cycle.
5.45
TCK (Test Clock)
Input, Internal Pullup
Summary
TCK is the clock for boundary-scan testing using the Test
Access Port (TAP). See “Boundary-Scan Test Access Port
(TAP)” on page 205 for details regarding the operation of the
TAP controller.
Sampled
The processor always samples TCK, except while TRST# is
asserted.
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TDI (Test Data Input)
Input, Internal Pullup
Summary
T D I i s t h e s e r i a l t e s t d a t a a n d i n s t r u c t i o n i n p u t fo r
boundary-scan testing using the Test Access Port (TAP). See
“Boundary-Scan Test Access Port (TAP)” on page 205 for details
regarding the operation of the TAP controller.
Sampled
The processor samples TDI on every rising TCK edge but only
while in the Shift-IR and Shift-DR states.
5.47
TDO (Test Data Output)
Output
Summary
TDO is the serial test data and instruction out put for
boundary-scan testing using the Test Access Port (TAP). See
“Boundary-Scan Test Access Port (TAP)” on page 205 for details
regarding the operation of the TAP controller.
Driven and Floated
The processor drives TDO on every falling TCK edge but only
while in the Shift-IR and Shift-DR states. TDO is floated at all
other times.
5.48
TMS (Test Mode Select)
Input, Internal Pullup
Summary
TMS specifies the test function and sequence of state changes
for boundary-scan testing using the Test Access Port (TAP). See
“Boundary-Scan Test Access Port (TAP)” on page 205 for details
regarding the operation of the TAP controller.
Sampled
The processor samples TMS on every rising TCK edge. If TMS is
sampled High for five or more consecutive clocks, the TAP
controller enters its Test-Logic-Reset state, regardless of the
controller state. This action is the same as that achieved by
asserting TRST#.
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5.49
TRST# (Test Reset)
Input, Internal Pullup
Summary
The assertion of TRST# initializes the Test Access Port (TAP) by
resetting its state machine to the Test-Logic-Reset state. See
“Boundary-Scan Test Access Port (TAP)” on page 205 for details
regarding the operation of the TAP controller.
Sampled
TRST# is a completely asynchronous input that does not
require a minimum setup and hold time relative to TCK. See
Table 54 on page 253 for the minimum pulse width requirement.
5.50
VCC2DET (VCC2 Detect)
Output
Summary
VCC2DET is tied to VSS (logic level 0) to indicate to the system
logic that it must supply the specified processor core voltage to
the VCC2 pins. The VCC2 pins supply voltage to the processor
core, independent of the voltage supplied to the I/O buffers on
the VCC3 pins.
Driven
VCC2DET always equals 0 and is never floated—even during
Tri-State Test mode.
5.51
W/R# (Write/Read)
Output
Summary
The processor drives W/R# to indicate whether it is performing
a write or a read cycle on the bus. In addition, W/R# is used to
define other bus cycles, including interrupt acknowledge and
special cycles (see Table 19 on page 119 for more details).
Driven and Floated
W/R# is driven off the same clock edge as ADS# and remains in
the same state until the clock edge on which NA# or the last
expected BRDY# of the cycle is sampled asserted. W/R# is
driven during memory cycles, I/O cycles, special bus cycles, and
interrupt acknowledge cycles.
W/R# is floated off the clock edge that BOFF# is sampled
asserted and off the clock edge that the processor asserts HLDA
in response to HOLD.
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5.52
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WB/WT# (Writeback or Writethrough)
Input
Summary
WB/WT#, together with PWT, specifies the data cache-line state
during cacheable read misses and write hits to shared cache
lines.
If WB/WT# = 0 or PWT = 1 during a cacheable read miss or write
hit to a shared cache line, the accessed line is cached in the
shared state. This is referred to as the writethrough state
because all write cycles to this cache line are driven externally
on the bus.
If WB/WT# = 1 and PWT = 0 during a cacheable read miss or a
write hit to a shared cache line, the accessed line is cached in
the exclusive state. Subsequent write hits to the same line
cause its state to transition from exclusive to modified. This is
referred to as the writeback state because the data cache can
contain modified cache lines that are subject to be written
back—referred as a writeback cycle—as the result of an inquire
cycle, an internal snoop, a flush operation, or the WBINVD
instruction.
Sampled
116
WB/WT# is sampled on the clock edge that the first BRDY# or
NA# of a bus cycle is sampled asserted. If the cycle is a burst
read, WB/WT# is ignored during the last three assertions of
BRDY #. WB /WT# is sampled during mem ory re ad and
non-writeback write cycles and is ignored during all other types
of cycles.
Signal Descriptions
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Preliminary Information
AMD-K6® Processor Data Sheet
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Table 14. Input Pin Types
Name
Type
Note
A20M#
Asynchronous
Note 1
AHOLD
Synchronous
BF[2:0]
Synchronous
Type
Note
IGNNE#
Asynchronous
Note 1
INIT
Asynchronous
Note 2
INTR
Asynchronous
Note 1
BOFF#
Synchronous
INV
Synchronous
BRDY#
Synchronous
KEN#
Synchronous
BRDYC#
Synchronous
NA#
Synchronous
NMI
Asynchronous
Note 2
CLK
Note 4
Note 7
Clock
Name
EADS#
Synchronous
RESET
Asynchronous
Note 5, 6
EWBE#
Synchronous
SMI#
Asynchronous
Note 2
FLUSH#
Asynchronous
STPCLK#
Asynchronous
Note 1
HOLD
Synchronous
WB/WT#
Synchronous
Note 2, 3
Notes:
1. These level-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must be asserted for a minimum pulse width of two clocks.
2. These edge-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must have been negated at least two clocks prior to assertion and must
remain asserted at least two clocks.
3. FLUSH# is also sampled during the falling transition of RESET and can be asserted synchronously or asynchronously. To be
sampled on a specific clock edge, setup and hold times must be met the clock edge before the clock edge on which RESET is
sampled negated. If asserted asynchronously, FLUSH# must meet a minimum setup and hold time of two clocks relative to the
negation of RESET.
4. BF[2:0] are sampled during the falling transition of RESET. They must meet a minimum setup time of 1.0 ms and a minimum hold
time of two clocks relative to the negation of RESET.
5. During the initial power-on reset of the processor, RESET must remain asserted for a minimum of 1.0 ms after CLK and VCC reach
specification before it is negated.
6. During a warm reset, while CLK and VCC are within their specification, RESET must remain asserted for a minimum of 15 clocks
prior to its negation.
7. BRDYC# is also sampled during the falling transition of RESET. If RESET is driven synchronously, BRDYC# must meet the specified
hold time relative to the negation of RESET. If asserted asynchronously, BRDYC# must meet a minimum setup and hold time of
two clocks relative to the negation of RESET.
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Table 15. Output Pin Float Conditions
Name
Floated At: (Note 1)
Note
A[4:3]
HLDA, AHOLD, BOFF#
Note 2, 3
HITM#
Always Driven
ADS#
HLDA, BOFF#
Note 2
HLDA
Always Driven
ADSC#
HLDA, BOFF#
Note 2
LOCK#
HLDA, BOFF#
Note 2
APCHK#
Always Driven
M/IO#
HLDA, BOFF#
Note 2
BE[7:0]#
HLDA, BOFF#
PCD
HLDA, BOFF#
Note 2
BREQ
Always Driven
PCHK#
Always Driven
CACHE#
HLDA, BOFF#
Note 2
PWT
HLDA, BOFF#
Note 2
D/C#
HLDA, BOFF#
Note 2
SCYC
HLDA, BOFF#
Note 2
FERR#
Always Driven
SMIACT#
Always Driven
HIT#
Always Driven
W/R#
HLDA, BOFF#
Note 2
Name
Floated At: (Note 1)
Note
Note 2
Notes:
1. All outputs except VCC2DET and TDO float during Tri-State Test mode.
2. Floated off the clock edge that BOFF# is sampled asserted and off the clock edge that HLDA is asserted.
3. Floated off the clock edge that AHOLD is sampled asserted.
Table 16. Input/Output Pin Float Conditions
Name
Floated At: (Note 1)
Note
A[31:5]
HLDA, AHOLD, BOFF#
Note 2,3
AP
HLDA, AHOLD, BOFF#
Note 2,3
D[63:0]
HLDA, BOFF#
Note 2
DP[7:0]
HLDA, BOFF#
Note 2
Notes:
1. All outputs except VCC2DET and TDO float during Tri-State Test mode.
2. Floated off the clock edge that BOFF# is sampled asserted and off the clock edge that HLDA is asserted.
3. Floated off the clock edge that AHOLD is sampled asserted.
Table 17. Test Pins
Name
Type
Note
TCK
Clock
TDI
Input
Sampled on the rising edge of TCK
TDO
Output
Driven on the falling edge of TCK
TMS
Input
Sampled on the rising edge of TCK
TRST#
Input
Asynchronous (Independent of TCK)
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Table 18. Bus Cycle Definition
Generated
by System
Generated by Processor
Bus Cycle Initiated
M/IO#
D/C#
W/R#
CACHE#
KEN#
Code Read, Instruction Cache Line Fill
1
0
0
0
0
Code Read, Noncacheable
1
0
0
1
x
Code Read, Noncacheable
1
0
0
x
1
Encoding for Special Cycle
0
0
1
1
x
Interrupt Acknowledge
0
0
0
1
x
I/O Read
0
1
0
1
x
I/O Write
0
1
1
1
x
Memory Read, Data Cache Line Fill
1
1
0
0
0
Memory Read, Noncacheable
1
1
0
1
x
Memory Read, Noncacheable
1
1
0
x
1
Memory Write, Data Cache Writeback
1
1
1
0
x
Memory Write, Noncacheable
1
1
1
1
x
Note:
x means “don’t care”
A4
BE7#
BE6#
BE5#
BE4#
BE3#
BE2#
BE1#
BE0#
M/IO#
D/C#
W/R#
CACHE#
KEN#
Table 19. Special Cycles
Stop Grant
1
1
1
1
1
1
0
1
1
0
0
1
1
x
Flush Acknowledge
(FLUSH# sampled asserted)
0
1
1
1
0
1
1
1
1
0
0
1
1
x
Writeback
(WBINVD instruction)
0
1
1
1
1
0
1
1
1
0
0
1
1
x
Halt
0
1
1
1
1
1
0
1
1
0
0
1
1
x
Flush (INVD, WBINVD
instruction)
0
1
1
1
1
1
1
0
1
0
0
1
1
x
Shutdown
0
1
1
1
1
1
1
1
0
0
0
1
1
x
Special Cycle
Note:
x means “don’t care”
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Signal Descriptions
Chapter 5
Preliminary Information
AMD-K6® Processor Data Sheet
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6
Bus Cycles
The following sections describe and illustrate the timing and
relationship of bus signals during various types of bus cycles. A
representative set of bus cycles is illustrated.
6.1
Timing Diagrams
The timing diagrams illustrate the signals on the external local
bus as a function of time, as measured by the bus clock (CLK).
Throughout this chapter, the term clock refers to a signal
bus-clock cycle. A clock extends from one rising CLK edge to
the next rising CLK edge. The processor samples and drives
most signals relative to the rising edge of CLK. The exceptions
to this rule include the following:
■
■
■
BF[2:0]—Sampled on the falling edge of RESET
FLUSH#, BRDYC#—Sampled on the falling edge of RESET,
also sampled on the rising edge of CLK
All inputs and outputs are sampled relative to TCK in
Boundary-Scan Test Mode. Inputs are sampled on the rising
edge of TCK, outputs are driven off of the falling edge of
TCK.
For each signal in the timing diagrams, the High level
represents 1, the Low level represents 0, and the Middle level
represents the floating (high-impedance) state. When both the
High and Low levels are shown, the meaning depends on the
signal. A single signal indicates ‘don’t care’. In the case of bus
activity, if both High and Low levels are shown, it indicates the
processor, alternate master, or system logic is driving a value,
but this value may or may not be valid. (For example, the value
on the address bus is valid only during the assertion of ADS#,
but addresses are also driven on the bus at other times.) Figure
43 on page 122 defines the different waveform representations.
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Description
Waveform
Don’t care or bus is driven
Signal or bus is changing from Low to High
Signal or bus is changing from High to Low
Bus is changing
Bus is changing from valid to invalid
Signal or bus is floating
Denotes multiple clock periods
Figure 43. Waveform Definitions
For all active-High signals, the term asserted means the signal is
in the High-voltage state and the term negated means the signal
is in the Low-voltage state. For all active-Low signals, the term
asserted means the signal is in the Low-voltage state and the
term negated means the signal is in the High-voltage state.
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6.2
Bus State Machine Diagram
Bus State
Branch Condition
Addr
No
Pending
Request?
Yes
Address
Data
Idle
Data
Idle
Yes
Last BRDY#
Asserted?
No
NA# Sampled
Asserted?
Data-NA#
Yes
No
Yes
Data-NA#
Requested
Last BRDY#
Asserted?
No
Yes
No
Pending
Request?
Pipe-A
NA# Sampled
Asserted?
No
Yes
Pipeline
Address
Pipe-D
Pipeline
Data
No
Last BRDY#
Asserted?
Yes
Trans
Yes
NA# Sampled
Asserted?
Transition
Yes
Bus Transition?
No
No
Note:
The processor transitions to the IDLE state on the clock edge on which BOFF# or RESET is sampled asserted.
Figure 44. Bus State Machine Diagram
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Idle
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The processor does not drive the system bus in the Idle state
and remains in this state until a new bus cycle is requested. The
processor enters this state off the clock edge on which the last
BRDY# of a cycle is sampled asserted during the following
conditions:
■
■
The processor is in the Data state
The processor is in the Data-NA# Requested state and no
internal pending cycle is requested
In addition, the processor is forced into this state when the
system logic asserts RESET or BOFF#. The transition to this
state occurs on the clock edge on which RESET or BOFF# is
sampled asserted.
Address
In this state, the processor drives ADS# to indicate the
beginning of a new bus cycle by validating the address and
control signals. The processor remains in this state for one clock
and unconditionally enters the Data state on the next clock
edge.
Data
In the Data state, the processor drives the data bus during a
write cycle or expects data to be returned during a read cycle.
The processor remains in this state until either NA# or the last
BRDY# is sampled asserted. If the last BRDY# is sampled
asserted or both the last BRDY# and NA# are sampled asserted
on the same clock edge, the processor enters the Idle state. If
NA# is sampled asserted first, the processor enters the
Data-NA# Requested state.
Data-NA# Requested
If the processor samples NA# asserted while in the Data state
and the current bus cycle is not completed (the last BRDY# is
not sampled asserted), it enters the Data-NA# Requested state.
The processor remains in this state until either the last BRDY#
is sampled asserted or an internal pending cycle is requested. If
the last BRDY# is sampled asserted before the processor drives
a new bus cycle, the processor enters the Idle state (no internal
pending cycle is requested) or the Address state (processor has
a internal pending cycle).
Pipeline Address
In this state, the processor drives ADS# to indicate the
beginning of a new bus cycle by validating the address and
control signals. In this state, the processor is still waiting for the
current bus cycle to be completed (until the last BRDY# is
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sampled asserted). If the last BRDY# is not sampled asserted,
the processor enters the Pipeline Data state.
If the processor samples the last BRDY# asserted in this state, it
determines if a bus transition is required between the current
bus cycle and the pipelined bus cycle. A bus transition is
required when the data bus direction changes between bus
cycles, such as a memory write cycle followed by a memory read
cycle. If a bus transition is required, the processor enters the
Transition state for one clock to prevent data bus contention. If
a bus transition is not required, the processor enters the Data
state.
The processor does not transition to the Data-NA# Requested
state from the Pipeline Address state because the processor
does not begin sampling NA# until it has exited the Pipeline
Address state.
Pipeline Data
Two bus cycles are concurrently executing in this state. The
processor cannot issue any additional bus cycles until the
current bus cycle is completed. The processor drives the data
bus during write cycles or expects data to be returned during
read cycles for the current bus cycle until the last BRDY# of the
current bus cycle is sampled asserted.
If the processor samples the last BRDY# asserted in this state, it
determines if a bus transition is required between the current
bus cycle and the pipelined bus cycle. If the bus transition is
required, the processor enters the Transition state for one clock
to prevent data bus contention. If a bus transition is not
required, the processor enters the Data state (NA# was not
sampled asserted) or the Data-NA# Requested state (NA# was
sampled asserted).
Transition
Chapter 6
The processor enters this state for one clock during data bus
transitions and enters the Data state on the next clock edge if
NA# is not sampled asserted. The sole purpose of this state is to
avoid bus contention caused by bus transitions during pipeline
operation.
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6.3
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Memory Reads and Writes
The AMD-K6 processor performs single or burst memory bus
cycles. The single-transfer memory bus cycle transfers 1, 2, 4, or
8 bytes and requires a minimum of two clocks. Misaligned
instructions or operands result in a split cycle, which requires
multiple transactions on the bus. A burst cycle consists of four
back-to-back 8-byte (64-bit) transfers on the data bus.
Single-Transfer
Memory Read and
Write
Figure 45 on page 127 shows a single-transfer read from memory,
followed by two single-transfer writes to memory. For the
memory read cycle, the processor asserts ADS# for one clock to
validate the bus cycle and also drives A[31:3], BE[7:0]#, D/C#,
W/R#, and M/IO# to the bus. The processor then waits for the
system logic to return the data on D[63:0] (with DP[7:0] for
parity checking) and assert BRDY#. The processor samples
BRDY# on every clock edge starting with the clock edge after
the clock edge that negates ADS#. See “BRDY# (Burst Ready)”
on page 88.
During the read cycle, the processor drives PCD, PWT, and
CACHE# to indicate its caching and cache-coherency intent for
the access. The system logic returns KEN# and WB/WT# to
either confirm or change this intent. If the processor asserts
PCD and negates CACHE#, the accesses are non-cacheable,
even though the system logic asserts KEN# during the BRDY#
to indicate its support for cacheability. The processor (which
drives CACHE#) and the system logic (which drives KEN#) must
agree in order for an access to be cacheable.
The processor can drive another cycle (in this example, a write
cycle) by asserting ADS# off the next clock edge after BRDY# is
sampled asserted. Therefore, an idle clock is guaranteed
between any two bus cycles. The processor drives D[63:0] with
valid data one clock edge after the clock edge on which ADS# is
asserted. To minimize CPU idle times, the system logic stores the
address and data in write buffers, returns BRDY#, and performs
the store to memory later. If the processor samples EWBE#
negated during a write cycle, it suspends certain activities until
EWBE# is sampled asserted. See “EWBE# (External Write
Buffer Empty)” on page 95. In Figure 45, the second write cycle
occurs during the execution of a serializing instruction. The
processor delays the following cycle until EWBE# is sampled
asserted.
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Read Cycle
ADDR DATA
IDLE
Write Cycle (Next Cycle Delayed by EWBE#)
Write Cycle
ADDR DATA DATA
IDLE
ADDR DATA DATA
IDLE
IDLE
IDLE
IDLE
IDLE
ADDR
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
BREQ
D[63:0]
DP[7:0]
CACHE#
EWBE#
KEN#
BRDY#
WB/WT#
Figure 45. Non-Pipelined Single-Transfer Memory Read/Write and Write Delayed by EWBE#
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Misaligned
Single-Transfer
Memory Read and
Write
20695H/0—March 1998
Figure 46 on page 129 shows a misaligned (split) memory read
followed by a misaligned memory write. Any cycle that is not
aligned as defined in “SCYC (Split Cycle)” on page 111 is
considered misaligned. When the processor encounters a
misaligned access, it determines the appropriate pair of bus
cycles — each with its own ADS# and BRDY# — required to
complete the access.
The AMD-K6 processor performs misaligned memory reads and
memory writes using least-significant bytes (LSBs) first
followed by most-significant bytes (MSBs). Table 20 shows the
order. In the first memory read cycle in Figure 46, the processor
reads the least-significant bytes. Immediately after the
processor samples BRDY# asserted, it drives the second bus
cycle to read the most-significant bytes to complete the
misaligned transfer.
Table 20. Bus-Cycle Order During Misaligned Transfers
Type of Access
First Cycle
Second Cycle
Memory Read
LSBs
MSBs
Memory Write
LSBs
MSBs
Similarly, the misaligned memory write cycle in Figure 46
transfers the LSBs to the memory bus first. In the next cycle,
after the processor samples BRDY# asserted, the MSBs are
written to the memory bus.
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Memory Read (Misaligned)
Memory Write (Misaligned)
ADDR DATA DATA IDLE ADDR DATA DATA IDLE ADDR DATA DATA DATA IDLE ADDR DATA DATA DATA IDLE
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
D[63:0]
LSB
MSB
LSB
MSB
BRDY#
Figure 46. Misaligned Single-Transfer Memory Read and Write
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AMD-K6® Processor Data Sheet
Burst Reads and
Pipelined Burst Reads
20695H/0—March 1998
Figure 47 on page 131 shows normal burst read cycles and a
pipelined burst read cycle. The AMD-K6 processor drives
CACHE# and ADS# together to specify that the current bus
cycle is a burst cycle. If the processor samples KEN# asserted
with the first BRDY#, it performs burst transfers. During the
burst transfers, the system logic must ignore BE[7:0]# and must
return all eight bytes beginning at the starting address the
processor asserts on A[31:3]. Depending on the starting
address, the system logic must determine the successive
quadword addresses (A[4:3]) for each transfer in a burst, as
shown in Table 21. The processor expects the second, third, and
fourth quadwords to occur in the sequences shown in Table 21.
Table 21. A[4:3] Address-Generation Sequence During Bursts
Address Driven By
Processor on A[4:3]
A[4:3] Addresses of Subsequent
Quadwords* Generated By System Logic
Quadword 1
Quadword 2
Quadword 3
Quadword 4
00b
01b
10b
11b
01b
00b
11b
10b
10b
11b
00b
01b
11b
10b
01b
00b
Note:
*
quadword = 8 bytes
In Figure 47, the processor drives CACHE# throughout all burst
read cycles. In the first burst read cycle, the processor drives
ADS# and CACHE#, then samples BRDY# on every clock edge
starting with the clock edge after the clock edge that negates
ADS#. The processor samples KEN# asserted on the clock edge
on which the first BRDY# is sampled asserted, executes a
32-byte burst read cycle, and expects to sample BRDY# a total
of four times. An ideal no-wait state access is shown in Figure
47, whereas most system logic solutions add wait states between
the transfers.
The second burst read cycle illustrates a similar sequence, but
the processor samples NA# asserted on the same clock edge
that the first BRDY# is sampled asserted. NA# assertion
indicates the system logic is requesting the processor to output
the next address early (also known as a pipeline transfer
request). Without waiting for the current cycle to complete, the
processor drives ADS# and related signals for the next burst
cycle. Pipelining can reduce CPU cycle-to-cycle idle times.
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Burst Read
Burst Read
Pipelined Burst Read
ADDR DATA DATA DATA DATA IDLE ADDR DATA DATA DATA
-NA PIPE-A DATA DATA DATA DATA IDLE
CLK
A[31:3]
ADDR1
ADDR2
ADDR3
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
NA#
D[63:0]
DATA1
DATA2
DATA3
CACHE#
KEN#
BRDY#
Figure 47. Burst Reads and Pipelined Burst Reads
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Burst Writeback
20695H/0—March 1998
Figure 48 on page 133 shows a burst read followed by a
writeback transaction. The AMD-K6 processor initiates
writebacks under the following conditions:
■
■
■
■
Replacement—If a cache-line fill is initiated for a cache line
currently filled with valid entries, the processor uses a
least-recently-allocated (LRA) algorithm to select a line for
replacement. Before a replacement is made to a data cache
line that is in the modified state, the modified line is
scheduled to be written back to memory.
Internal Snoop—The processor snoops the data cache
whenever an instruction-cache line is read, and it snoops the
instruction cache whenever a data cache line is written. This
snooping is performed to determine whether the same
address is stored in both caches, a situation that is taken to
imply the occurrence of self-modifying code. If a snoop hits a
data cache line in the modified state, the line is written back
to memory before being invalidated.
WBINVD Instruction—When the processor executes a
WBINVD instruction, it writes back all modified lines in the
data cache and then invalidates all lines in both caches.
Cache Flush—When the processor samples FLUSH#
asserted, it executes a flush acknowledge special cycle and
writes back all modified lines in the data cache and then
invalidates all lines in both caches.
The processor drives writeback cycles during inquire or cache
flush cycles. The writeback shown in Figure 48 is caused by a
cache-line replacement. The processor completes the burst read
cycle that fills the cache line. Immediately following the burst
read cycle is the burst writeback cycle that represents the
modified line to be written back to memory. D[63:0] are driven
one clock edge after the clock edge on which ADS# is asserted
and are subsequently changed off the clock edge on which each
BRDY# assertion of the burst cycle is sampled.
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Burst Writeback from L1 Cache
Burst Read
ADDR
DATA
DATA
DATA
DATA
IDLE
ADDR
DATA
DATA
DATA
DATA
IDLE
CLK
A[31:3]
BE[7:0]#
ADS#
CACHE#
M/IO#
D/C#
W/R#
D[63:0]
KEN#
BRDY#
WB/WT#
Figure 48. Burst Writeback due to Cache-Line Replacement
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Preliminary Information
AMD-K6® Processor Data Sheet
6.4
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I/O Read and Write
Basic I/O Read and
Write
The processor accesses I/O when it executes an I/O instruction
(for example, IN or OUT). Figure 49 shows an I/O read followed
by an I/O write. The processor drives M/IO# Low and D/C# High
during I/O cycles. In this example, the first cycle shows a single
wait state I/O read cycle. It follows the same sequence as a
single-transfer memory read cycle. The processor drives ADS#
to initiate the bus cycle, then it samples BRDY# on every clock
edge starting with the clock edge after the clock edge that
negates ADS#. The system logic must return BRDY# to
complete the cycle. When the processor samples BRDY#
asserted, it can assert ADS# for the next cycle off the next clock
edge. (In this example, an I/O write cycle.)
The I/O write cycle is similar to a memory write cycle, but the
processor drives M/IO# low during an I/O write cycle. The
processor asserts ADS# to initiate the bus cycle. The processor
drives D[63:0] with valid data one clock edge after the clock
edge on which ADS# is asserted. The system logic must assert
BRDY# when the data is properly stored to the I/O destination.
The processor samples BRDY# on every clock edge starting with
the clock edge after the clock edge that negates ADS#. In this
example, two wait states are inserted while the processor waits
for BRDY# to be asserted.
I/O Write Cycle
I/O Read Cycle
ADDR
DATA
DATA
IDLE
ADDR
DATA
DATA
DATA
IDLE
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
D[63:0]
BRDY#
Figure 49. Basic I/O Read and Write
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Misaligned I/O Read
and Write
Table 22 shows the misaligned I/O read and write cycle order
executed by the AMD-K6. In Figure 50, the least-significant
bytes (LSBs) are transferred first. Immediately after the
processor samples BRDY# asserted, it drives the second bus
cycle to transfer the most-significant bytes (MSBs) to complete
the misaligned bus cycle.
Table 22. Bus-Cycle Order During Misaligned I/O Transfers
Type of Access
First Cycle
Second Cycle
I/O Read
LSBs
MSBs
I/O Write
LSBs
MSBs
Misaligned I/O Write
Misaligned I/O Read
ADDR DATA DATA IDLE ADDR DATA DATA IDLE ADDR DATA DATA DATA IDLE ADDR DATA DATA DATA IDLE
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
LOCK#
SCYC
D[63:0]
LSB
MSB
LSB
MSB
BRDY#
Figure 50. Misaligned I/O Transfer
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Preliminary Information
AMD-K6® Processor Data Sheet
6.5
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Inquire and Bus Arbitration Cycles
The AMD-K6 processor provides built-in level-one data and
instruction caches. Each cache is 32 Kbytes and two-way
set-associative. The system logic or other bus master devices
can initiate an inquire cycle to maintain cache/memory
coherency. In response to the inquire cycle, the processor
compares the inquire address with its cache tag addresses in
both caches, and, if necessary, updates the MESI state of the
cache line and performs writebacks to memory.
An inquire cycle can be initiated by asserting AHOLD, BOFF#,
or HOLD. AHOLD is exclusively used to support inquire cycles.
During AHOLD-initiated inquire cycles, the processor only
floats the address bus. BOFF# provides the fastest access to the
bus because it aborts any processor cycle that is in-progress,
whereas AHOLD and HOLD both permit an in-progress bus
cycle to complete. During HOLD-initiated and BOFF#-initiated
inquire cycles, the processor floats all of its bus-driving signals.
Hold and Hold
Acknowledge Cycle
The system logic or another bus device can assert HOLD to
initiate an inquire cycle or to gain full control of the bus. When
the AMD-K6 processor samples HOLD asserted, it completes
any in-progress bus cycle and asserts HLDA to acknowledge
release of the bus. The processor floats the following signals off
the same clock edge that HLDA is asserted:
■
■
■
■
■
■
■
A[31:3]
ADS#
AP#
BE[7:0]#
CACHE#
D[63:0]
D/C#
■
■
■
■
■
■
■
DP[7:0]
LOCK#
M/IO#
PCD
PWT
SCYC
W/R#
Figure 51 on page 137 shows a basic HOLD/HLDA operation. In
this example, the processor samples HOLD asserted during the
memory read cycle. It continues the current memory read cycle
until BRDY# is sampled asserted. The processor drives HLDA
and floats its outputs one clock edge after the last BRDY# of the
cycle is sampled asserted. The system logic can assert HOLD for
as long as it needs to utilize the bus. The processor samples
HOLD on every clock edge but does not assert HLDA until any
in-progress cycle or sequence of locked cycles is completed.
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AMD-K6® Processor Data Sheet
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When the processor samples HOLD negated during a hold
acknowledge cycle, it negates HLDA off the next clock edge.
The processor regains control of the bus and can assert ADS#
off the same clock edge on which HLDA is negated.
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
D[63:0]
HOLD
HLDA
BRDY#
Figure 51. Basic HOLD/HLDA Operation
Chapter 6
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Preliminary Information
AMD-K6® Processor Data Sheet
HOLD-Initiated
Inquire Hit to Shared
or Exclusive Line
20695H/0—March 1998
Figure 52 on page 139 shows a HOLD-initiated inquire cycle. In
this example, the processor samples HOLD asserted during the
burst memory read cycle. The processor completes the current
cycle (until the last expected BRDY# is sampled asserted),
asserts HLDA and floats its outputs as described on page 136.
The system logic drives an inquire cycle within the hold
acknowledge cycle. It asserts EADS#, which validates the
inquire address on A[31:5]. If EADS# is sampled asserted
before HOLD is sampled negated, the processor recognizes it as
a valid inquire cycle.
In Figure 52, the processor asserts HIT# and negates HITM# on
the clock edge after the clock edge on which EADS# is sampled
asserted, indicating the current inquire cycle hit a shared or
exclusive cache line. (Shared and exclusive cache lines in the
processor data or instruction cache have the same contents as
the data in the external memory.) During an inquire cycle, the
processor samples INV to determine whether the addressed
cache line found in the processor’s instruction or data cache
transitions to the invalid state or the shared state. In this
example, the processor samples INV asserted with EADS#,
which invalidates the cache line.
The system logic can negate HOLD off the same clock edge on
which EADS# is sampled asserted. The processor continues
driving HIT# in the same state until the next inquire cycle.
HITM# is not asserted unless HIT# is asserted.
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Burst Memory Read
Inquire
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
HIT#
HITM#
D[63:0]
KEN#
BRDY#
HOLD
HLDA
EADS#
INV
Figure 52. HOLD-Initiated Inquire Hit to Shared or Exclusive Line
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Preliminary Information
AMD-K6® Processor Data Sheet
HOLD-Initiated
Inquire Hit to
Modified Line
20695H/0—March 1998
Figure 53 on page 141 shows the same sequence as Figure 52 on
page 139, but in Figure 53 the inquire cycle hits a modified line
and the processor asserts both HIT# and HITM#. In this
example, the processor performs a writeback cycle immediately
after the inquire cycle. It updates the modified cache line to the
external memory (normally, level-two cache or DRAM). The
processor uses the address (A[31:5]) that was latched during the
inquire cycle to perform the writeback cycle. The processor
asserts HITM# throughout the writeback cycle and negates
HITM# one clock edge after the last expected BRDY# of the
writeback is sampled asserted.
When the processor samples EADS# during the inquire cycle, it
also samples INV to determine the cache line MESI state after
the inquire cycle. If INV is sampled asserted during an inquire
cycle, the processor transitions the line (if found) to the invalid
stat e, regardless of its previous sta te. The cache line
invalidation operation is not visible on the bus. If INV is
sampled negated during an inquire cycle, the processor
transitions the line (if found) to the shared state. In Figure 53
the processor samples INV asserted during the inquire cycle.
In a HOLD-initiated inquire cycle, the system logic can negate
HOLD off the same clock edge on which EADS# is sampled
asserted. The processor drives HIT# and HITM# on the clock
edge after the clock edge on which EADS# is sampled asserted.
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Burst Memory Read
Inquire
Writeback Cycle
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
HIT#
HITM#
D[63:0]
KEN#
BRDY#
HOLD
HLDA
EADS#
INV
Figure 53. HOLD-Initiated Inquire Hit to Modified Line
Chapter 6
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141
Preliminary Information
AMD-K6® Processor Data Sheet
AHOLD-Initiated
Inquire Miss
20695H/0—March 1998
AHOLD can be asserted by the system to initiate one or more
inquire cycles. To allow the system to drive the address bus
during an inquire cycle, the processor floats A[31:3] and AP off
the clock edge on which AHOLD is sampled asserted. The data
bus and all other control and status signals remain under the
control of the processor and are not floated. This functionality
allows a bus cycle in progress when AHOLD is sampled asserted
to continue to completion. The processor resumes driving the
address bus off the clock edge on which AHOLD is sampled
negated.
In Figure 54 on page 143, the processor samples AHOLD
asserted during the memory burst read cycle, and it floats the
address bus off the same clock edge on which it samples AHOLD
asserted. While the processor still controls the bus, it completes
the current cycle until the last expected BRDY# is sampled
asserted. The system logic drives EADS# with an inquire
address on A[31:5] during an inquire cycle. The processor
samples EADS# asserted and compares the inquire address to
its tag address in both the instruction and data caches. In Figure
54, the inquire address misses the tag address in the processor
(both HIT# and HITM# are negated). Therefore, the processor
proceeds to the next cycle when it samples AHOLD negated.
(The processor can drive a new cycle by asserting ADS# off the
same clock edge that it samples AHOLD negated.)
For an AHOLD-initiated inquire cycle to be recognized, the
processor must sample AHOLD asserted for at least two
consecutive clocks before it samples EADS# asserted. If the
processor detects an address parity error during an inquire
cycle, APCHK# is asserted for one clock. The system logic must
respond appropriately to the assertion of this signal.
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Inquire
Read
CLK
A[31:3]
BE[7:0]#
AP
APCHK#
ADS#
HIT#
HITM#
D[63:0]
KEN#
BRDY#
AHOLD
EADS#
INV
Figure 54. AHOLD-Initiated Inquire Miss
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143
Preliminary Information
AMD-K6® Processor Data Sheet
AHOLD-Initiated
Inquire Hit to Shared
or Exclusive Line
20695H/0—March 1998
In Figure 55 on page 145, the processor asserts HIT# and
negates HITM# off the clock edge after the clock edge on which
EADS# is sampled asserted, indicating the current inquire
cycle hits either a shared or exclusive line. (HIT# is driven in
the same state until the next inquire cycle.) The processor
samples INV asserted during the inquire cycle and transitions
the line to the invalid state regardless of its previous state.
During an AHOLD-initiated inquire cycle, the processor
samples AHOLD on every clock edge until it is negated. In
Figure 55, the processor asserts ADS# off the same clock on
which AHOLD is sampled negated. If the inquire cycle hits a
modified line, the processor performs a writeback cycle before
it drives a new bus cycle. The next section describes the
AHOLD-initiated inquire cycle that hits a modified line.
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Inquire
Burst Memory Read
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
HIT#
HITM#
D[63:0]
KEN#
BRDY#
AHOLD
EADS#
INV
Figure 55. AHOLD-Initiated Inquire Hit to Shared or Exclusive Line
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Preliminary Information
AMD-K6® Processor Data Sheet
AHOLD-Initiated
Inquire Hit to
Modified Line
20695H/0—March 1998
Figure 56 on page 147 shows an AHOLD-initiated inquire cycle
that hits a modified line. During the inquire cycle in this
example, the processor asserts both HIT# and HITM# on the
clock edge after the clock edge that it samples EADS# asserted.
This condition indicates that the cache line exists in the
processor’s data cache in the modified state.
If the inquire cycle hits a modified line, the processor performs
a writeback cycle immediately after the inquire cycle to update
the modified cache line to shared memory (normally level-two
cache or DRAM). In Figure 56, the system logic holds AHOLD
asserted throughout the inquire cycle and the processor
writeback cycle. In this case, the processor is not driving the
address bus during the writeback cycle because AHOLD is
sampled asserted. The system logic writes the data to memory
by using its latched copy of the inquire cycle address. If the
processor samples AHOLD negated before it performs the
writeback cycle, it drives the writeback cycle by using the
address (A[31:5]) that it latched during the inquire cycle.
If INV is sampled asserted during an inquire cycle, the
processor transitions the line (if found) to the invalid state,
regardless of its previous state (the cache invalidation
operation is not visible on the bus). If INV is sampled negated
during an inquire cycle, the processor transitions the line (if
found) to the shared state. In either case, if the line is found in
the modified state, the processor writes it back to memory
before changing its state. Figure 56 shows that the processor
samples INV asserted during the inquire cycle and invalidates
the cache line after the inquire cycle.
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Burst Memory Read
Inquire
Writeback
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
HIT#
HITM#
D[63:0]
KEN#
BRDY#
AHOLD
EADS#
INV
Figure 56. AHOLD-Initiated Inquire Hit to Modified Line
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Preliminary Information
AMD-K6® Processor Data Sheet
AHOLD Restriction
When the system logic drives an AHOLD-initiated inquire
cycle, it must assert AHOLD for at least two clocks before it
asserts EADS#. This requirement guarantees the processor
recognizes and responds to the inquire cycle properly. The
processor’s 32 address bus drivers turn on almost immediately
after AHOLD is sampled negated. If the processor switches the
data bus (D[63:0] and DP[7:0]) during a write cycle off the same
clock edge that switches the address bus (A[31:3] and AP), the
processor switches 102 drivers simultaneously, which can lead
to ground-bounce spikes. Therefore, before negating AHOLD
the following restrictions must be observed by the system logic:
■
When the system logic negates AHOLD during a write cycle,
it must ensure that AHOLD is not sampled negated on the
clock edge on which BRDY# is sampled asserted (See Figure
57 on page 149).
■
When the system logic negates AHOLD during a writeback
cycle, it must ensure that AHOLD is not sampled negated on
the clock edge on which ADS# is negated (See Figure 57).
When a write cycle is pipelined into a read cycle, AHOLD
must not be sampled negated on the clock edge after the
clock edge on which the last BRDY# of the read cycle is
sampled asserted to avoid the processor simultaneously
driving the data bus (for the pending write cycle) and the
address bus off this same clock edge.
■
148
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AMD-K6® Processor Data Sheet
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CLK
ADS#
W/R#
HITM#
EADS#
D[63:0]
BRDY#
Legal AHOLD negation during write cycle
AHOLD
Illegal AHOLD negation during write cycle
The system must ensure that AHOLD is not sampled negated on the clock edge that ADS# is negated.
The system must ensure that AHOLD is not sampled negated on the clock edge on which BRDY# is sampled
asserted.
Figure 57. AHOLD Restriction
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AMD-K6® Processor Data Sheet
Bus Backoff (BOFF#)
20695H/0—March 1998
BOFF# provides the fastest response among bus-hold inputs.
Either the system logic or another bus master can assert BOFF#
to gain control of the bus immediately. BOFF# is also used to
resolve potential deadlock problems that arise as a result of
inquire cycles. The processor samples BOFF# on every clock
e d g e . I f B O F F # i s s a m p l e d a s s e r t e d , t h e p ro c e s s o r
unconditionally aborts any cycles in progress and transitions to
a bus hold state. (See “BOFF# (Backoff)” on page 87.) Figure 58
on page 151 shows a read cycle that is aborted when the
processor samples BOFF# asserted even though BRDY# is
sampled asserted on the same clock edge. The read cycle is
restarted after BOFF# is sampled negated (KEN# must be in
the same state during the restarted cycle as its state during the
aborted cycle).
During a BOFF#-initiated inquire cycle that hits a shared or
exclusive line, the processor samples BOFF# negated and
restarts any bus cycle that was aborted when BOFF# was
asserted. If a BOFF#-initiated inquire cycle hits a modified line,
the processor performs a writeback cycle before it restarts the
aborted cycle.
If the processor samples BOFF# asserted on the same clock
edge that it asserts ADS#, ADS# is floated but the system logic
may erroneously interpret ADS# as asserted. In this case, the
system logic must properly interpret the state of ADS# when
BOFF# is negated.
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Read
Back Off Cycle
Restart Read Cycle
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
BOFF#
D[63:0]
BRDY#
Figure 58. BOFF# Timing
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Preliminary Information
AMD-K6® Processor Data Sheet
Locked Cycles
20695H/0—March 1998
The processor asserts LOCK# during a sequence of bus cycles to
ensure the cycles are completed without allowing other bus
masters to intervene. Locked operations can consist of two to
five cycles. LOCK# is asserted during the following operations:
■
■
■
■
■
An interrupt acknowledge sequence
Descriptor Table accesses
Page Directory and Page Table accesses
XCHG instruction
An instruction with an allowable LOCK prefix
In order to ensure that locked operations appear on the bus and
are visible to the entire system, any data operands addressed
during a locked cycle that reside in the processor’s cache are
flushed and invalidated from the cache prior to the locked
operation. If the cache line is in the modified state, it is written
back and invalidated prior to the locked operation. Likewise,
any data read during a locked operation is not cached. The
processor negates LOCK# for at least one clock between
consecutive sequences of locked operations to allow the system
logic to arbitrate for the bus.
The processor asserts SCYC during misaligned locked transfers
on the D[63:0] data bus. The processor generates additional bus
cycles to complete the transfer of misaligned data.
Basic Locked
Operation
152
Figure 59 on page 153 shows a pair of read-write bus cycles. It
represents a typical read-modify-write locked operation. The
processor asserts LOCK# off the same clock edge that it asserts
ADS# of the first bus cycle in the locked operation and holds it
asserted until the last expected BRDY# of the last bus cycle in
the locked operation is sampled asserted. (The processor
negates LOCK# off the same clock edge.)
Bus Cycles
Chapter 6
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Locked Write Cycle
Locked Read Cycle
ADDR DATA DATA DATA IDLE IDLE ADDR DATA DATA DATA IDLE IDLE ADDR
CLK
A[31:3]
BE[7:0]#
ADS#
LOCK#
M/IO#
D/C#
W/R#
SCYC
D[63:0]
BRDY#
Figure 59. Basic Locked Operation
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Preliminary Information
AMD-K6® Processor Data Sheet
Locked Operation
with BOFF#
Intervention
20695H/0—March 1998
Figure 60 on page 155 shows BOFF# asserted within a locked
read-write pair of bus cycles. In this example, the processor
asserts LOCK# with ADS# to drive a locked memory read cycle
followed by a locked memory write cycle. During the locked
memory write cycle in this example, the processor samples
BOFF# asserted. The processor immediately aborts the locked
memory write cycle and floats all its bus-driving signals,
including LOCK#. The system logic or another bus master can
initiate an inquire cycle or drive a new bus cycle one clock edge
after the clock edge on which BOFF# is sampled asserted. If the
system logic drives a BOFF#-initiated inquire cycle and hits a
modified line, the processor performs a writeback cycle before
it restarts the locked cycle (the processor asserts LOCK# during
the writeback cycle).
In Figure 60, the processor immediately restarts the aborted
locked write cycle by driving the bus off the clock edge on
which BOFF# is sampled negated. The system logic must ensure
the processor results for interrupted and uninterrupted locked
cycles are consistent. That is, the system logic must guarantee
the memory accessed by the processor is not modified during
the time another bus master controls the bus.
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Locked Read Cycle
Aborted Write Cycle
Restart Write Cycle
CLK
A[31:3]
BE[7:0]#
ADS#
LOCK#
M/IO#
D/C#
W/R#
BOFF#
D[63:0]
BRDY#
Figure 60. Locked Operation with BOFF# Intervention
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Preliminary Information
AMD-K6® Processor Data Sheet
Interrupt
Acknowledge
20695H/0—March 1998
In response to recognizing the system’s maskable interrupt
(INTR), the processor drives an interrupt acknowledge cycle at
t h e n e x t i n s t r u c t i o n b o u n d a ry. D u r i n g a n i n t e r r u p t
acknowledge cycle, the processor drives a locked pair of read
cycles as shown in Figure 61 on page 157. The first read cycle is
not functional, and the second read cycle returns the interrupt
number on D[7:0] (00h–FFh). Table 23 shows the state of the
signals during an interrupt acknowledge cycle.
Table 23. Interrupt Acknowledge Operation Definition
Processor Outputs
First Bus Cycle
Second Bus Cycle
D/C#
Low
Low
M/IO#
Low
Low
W/R#
Low
Low
BE[7:0]#
EFh
FEh (low byte enabled)
A[31:3]
0000_0000h
0000_0000h
D[63:0]
(ignored)
Interrupt number expected from interrupt
controller on D[7:0]
The system logic can drive INTR either synchronously or
asynchronously. If it is asserted asynchronously, it must be
asserted for a minimum pulse width of two clocks. To ensure it
is recognized, INTR must remain asserted until an interrupt
acknowledge sequence is complete.
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Interrupt Acknowledge Cycles
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
LOCK#
INTR
D[63:0]
Interrupt Number
KEN#
BRDY#
Figure 61. Interrupt Acknowledge Operation
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Preliminary Information
AMD-K6® Processor Data Sheet
6.6
20695H/0—March 1998
Special Bus Cycles
The AMD-K6 processor drives special bus cycles that include
stop grant, flush acknowledge, cache writeback invalidation,
halt, cache invalidation, and shutdown cycles. During all
special cycles, D/C# = 0, M/IO# = 0, and W/R# = 1. BE[7:0]# and
A[31:3] are driven to differentiate among the special cycles, as
shown in Table 24. The system logic must return BRDY# in
response to all processor special cycles.
Table 24. Encodings For Special Bus Cycles
BE[7:0]#
A[4:3]*
Special Bus Cycle
Cause
FBh
10b
Stop Grant
EFh
00b
Flush Acknowledge FLUSH# sampled asserted
F7h
00b
Writeback
WBINVD instruction
FBh
00b
Halt
HLT instruction
FDh
00b
Flush
INVD,WBINVD instruction
FEh
00b
Shutdown
Triple fault
STPCLK# sampled asserted
Note:
*
Basic Special Bus
Cycle
A[31:5] = 0
Figure 62 on page 159 shows a basic special bus cycle. The
processor drives D/C# = 0, M/IO# = 0, and W/R# = 1 off the same
clock edge that it asserts ADS#. In this example, BE[7:0]# = FBh
and A[31:3] = 0000_0000h, which indicates that the special
cycle is a halt special cycle (See Table 24). A halt special cycle is
generated after the processor executes the HLT instruction.
If the processor samples FLUSH# asserted, it writes back any
data cache lines that are in the modified state and invalidates
all lines in the instruction and data cache. The processor then
drives a flush acknowledge special cycle.
If the processor executes a WBINVD instruction, it drives a
writeback special cycle after the processor completes
invalidating and writing back the cache lines.
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Halt Cycle
CLK
A[31:3]
BE[7:0]#
A[4:3] = 00b
FBh
ADS#
M/IO#
D/C#
W/R#
BRDY#
Figure 62. Basic Special Bus Cycle (Halt Cycle)
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Shutdown Cycle
20695H/0—March 1998
In Figure 63, a shutdown (triple fault) occurs in the first half of
the waveform, and a shutdown special cycle follows in the
second half. The processor enters shutdown when an interrupt
or exception occurs during the handling of a double fault (INT
8), which amounts to a triple fault. When the processor
encounters a triple fault, it stops its activity on the bus and
generates the shutdown special bus cycle (BE[7:0]# = FEh).
The system logic must assert NMI, INIT, RESET, or SMI# to get
the processor out of the shutdown state.
Shutdown Occurs
(Triple Fault)
Shutdown Special Cycle
CLK
A[4:3] = 00b
A[31:3]
FEh
BE[7:0]#
ADS#
LOCK#
M/IO#
D/C#
W/R#
D[63:0]
KEN#
BRDY#
Figure 63. Shutdown Cycle
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Stop Grant and Stop
Clock States
Figure 64 on page 162 and Figure 65 on page 163 show the
processor transition from normal execution to the Stop Grant
state, then to the Stop Clock state, back to the Stop Grant state,
and finally back to normal execution. The series of transitions
begins when the processor samples STPCLK# asserted. On
recognizing a STPCLK# interrupt at the next instruction
retirement boundary, the processor performs the following
actions, in the order shown:
1. Its instruction pipelines are flushed
2. All pending and in-progress bus cycles are completed
3. The STPCLK# assertion is acknowledged by executing a
Stop Grant special bus cycle
4. Its internal clock is stopped after BRDY# of the Stop Grant
special bus cycle is sampled asserted and after EWBE# is
sampled asserted
5. The Stop Clock state is entered if the system logic stops the
bus clock CLK (optional)
STPCLK# is sampled as a level-sensitive input on every clock
edge but is not recognized until the next instruction boundary.
The system logic drives the signal either synchronously or
asynchronously. If it is asserted asynchronously, it must be
asserted for a minimum pulse width of two clocks. STPCLK#
must remain asserted until recognized, which is indicated by
the completion of the Stop Grant special cycle.
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STPCLK# Sampled Asserted
Stop Grant Special Cycle
Stop Clock
CLK
A[4:3] = 10b
A[31:3]
FBh
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
CACHE#
STPCLK#
D[63:0]
KEN#
BRDY#
Figure 64. Stop Grant and Stop Clock Modes, Part 1
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Stop Clock
Stop Grant State
(Re-entered after PLL stabilization)
STPCLK# Sampled
Negated
Normal
CLK
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
CACHE#
STPCLK#
D[63:0]
KEN#
BRDY#
Figure 65. Stop Grant and Stop Clock Modes, Part 2
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INIT-Initiated
Transition from
Protected Mode to
Real Mode
20695H/0—March 1998
INIT is typically asserted in response to a BIOS interrupt that
writes to an I/O port. This interrupt is often in response to a
Ctrl-Alt-Del keyboard input. The BIOS writes to a port (similar
to port 64h in the keyboard controller) that asserts INIT. INIT is
also used to support 80286 software that must return to Real
mode after accessing extended memory in Protected mode.
The assertion of INIT causes the processor to empty its
pipelines, initialize most of its internal state, and branch to
address FFFF_FFF0h—the same instruction execution starting
point used after RESET. Unlike RESET, the processor
preserves the contents of its caches, the floating-point state, the
MMX state, Model-Specific Registers (MSRs), the CD and NW
bits of the CR0 register, the time stamp counter, and other
specific internal resources.
Figure 66 on page 165 shows an example in which the operating
system writes to an I/O port, causing the system logic to assert
INIT. The sampling of INIT asserted starts an extended
microcode sequence that terminates with a code fetch from
FFFF_FFF0h, the reset location. INIT is sampled on every clock
edge but is not recognized until the next instruction boundary.
During an I/O write cycle, it must be sampled asserted a
minimum of three clock edges before BRDY# is sampled
asserted if it is to be recognized on the boundary between the I/O
write instruction and the following instruction. If INIT is
asserted synchronously, it can be asserted for a minimum of one
clock. If it is asserted asynchronously, it must have been negated
for a minimum of two clocks, followed by an assertion of a
minimum of two clocks.
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INIT Sampled Asserted
CLK
Code Fetch
FFFF_FFF0
A[31:3]
BE[7:0]#
ADS#
M/IO#
D/C#
W/R#
D[63:0]
KEN#
BRDY#
INIT
Figure 66. INIT-Initiated Transition from Protected Mode to Real Mode
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7
Power-on Configuration and Initialization
On power-on the system logic must reset the AMD-K6 processor
by asserting the RESET signal. When the processor samples
RESET asserted, it immediately flushes and initializes all
internal resources and its internal state, including its pipelines
and caches, the floating-point state, the MMX state, and all
registers. Then the processor jumps to address FFFF_FFF0h to
start instruction execution.
7.1
Chapter 7
Signals Sampled During the Falling Transition of RESET
FLUSH#
FLUSH# is sampled on the falling transition of RESET to
determine if the processor begins normal instruction execution
or enters Tri-State Test mode. If FLUSH# is High during the
falling transition of RESET, the processor unconditionally runs
its Built-In Self Test (BIST), performs the normal reset
functions, then jumps to address FFFF_FFF0h to start
instruction execution. (See “Built-In Self-Test (BIST)” on page
203 for more details.) If FLUSH# is Low during the falling
transition of RESET, the processor enters Tri-State Test mode.
(See “Tri-State Test Mode” on page 204 and “FLUSH# (Cache
Flush)” on page 97 for more details.)
BF[2:0]
The in t er n a l op erat i n g f re q u e n cy o f t h e p roce s so r is
determined by the state of the bus frequency signals BF[2:0]
when they are sampled during the falling transition of RESET.
The frequency of the CLK input signal is multiplied internally
by a ratio defined by BF[2:0]. (See “BF[2:0] (Bus Frequency)”
on page 86 for the processor-clock to bus-clock ratios.)
BRDYC#
BRDYC# is sampled on the falling transition of RESET to
configure the drive strength of A[20:3], ADS#, HITM#, and
W/R#. If BRDYC# is Low during the fall of RESET, these
outputs are configured using higher drive strengths than the
standard strength. If BRDYC# is High during the fall of RESET,
the standard strength is selected. (See “BRDYC# (Burst Ready
Copy)” on page 89 for more details.)
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7.2
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RESET Requirements
During the initial power-on reset of the processor, RESET must
remain asserted for a minimum of 1.0 ms after CLK and VCC
reach specification. (See “CLK Switching Characteristics” on
page 241 for clock specifications. See “Electrical Data” on page
233 for VCC specifications.)
D u r i n g a wa r m re s e t w h i l e C L K a n d V C C a re w i t h i n
specification, RESET must remain asserted for a minimum of
15 clocks prior to its negation.
7.3
State of Processor After RESET
Output Signals
Table 25 show s the state of all processor outputs and
bidirectional signals immediately after RESET is sampled
asserted.
Table 25. Output Signal State After RESET
Signal
A[31:3], AP
168
Signal
State
Floating
HLDA
Low
ADS#, ADSC#
High
LOCK#
High
APCHK#
High
M/IO#
Low
BE[7:0]#
Floating
PCD
Low
BREQ
Low
PCHK#
High
CACHE#
High
PWT
Low
D/C#
Low
SCYC
Low
SMIACT#
High
D[63:0], DP[7:0]
Registers
State
Floating
FERR#
High
TDO
Floating
HIT#
High
VCC2DET
Low
HITM#
High
W/R#
Low
Table 26 on page 169 shows the state of all architecture
registers and Model-Specific Registers (MSRs) after the
processor has completed its initialization due to the recognition
of the assertion of RESET.
Power-on Configuration and Initialization
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Table 26. Register State After RESET
Register
State (hex)
Notes
GDTR
base:0000_0000h limit:0FFFFh
IDTR
base:0000_0000h limit:0FFFFh
TR
0000h
LDTR
0000h
EIP
FFFF_FFF0h
EFLAGS
0000_0002h
EAX
0000_0000h
EBX
0000_0000h
ECX
0000_0000h
EDX
0000_056Xh
ESI
0000_0000h
EDI
0000_0000h
EBP
0000_0000h
ESP
0000_0000h
CS
F000h
SS
0000h
DS
0000h
ES
0000h
FS
0000h
GS
0000h
FPU Stack R7–R0
0000_0000_0000_0000_0000h
3
FPU Control Word
0040h
3
FPU Status Word
0000h
3
FPU Tag Word
5555h
3
FPU Instruction Pointer
0000_0000_0000h
3
FPU Data Pointer
0000_0000_0000h
3
FPU Opcode Register
000_0000_0000b
3
CR0
6000_0010h
4
CR2
0000_0000h
1
2
Notes:
1. The contents of EAX indicate if BIST was successful. If EAX = 0000_0000h, BIST was successful.
If EAX is non-zero, BIST failed.
2. EDX contains the AMD-K6 processor signature, where X indicates the processor Stepping ID.
3. The contents of these registers are preserved following the recognition of INIT.
4. The CD and NW bits of CR0 are preserved following the recognition of INIT.
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Table 26. Register State After RESET (continued)
Register
State (hex)
Notes
CR3
0000_0000h
CR4
0000_0000h
DR7
0000_0400h
DR6
FFFF_0FF0h
DR3
0000_0000h
DR2
0000_0000h
DR1
0000_0000h
DR0
0000_0000h
MCAR
0000_0000_0000_0000h
3
MCTR
0000_0000_0000_0000h
3
TR12
0000_0000_0000_0000h
3
TSC
0000_0000_0000_0000h
3
WHCR
0000_0000_0000_0000h
3
Notes:
1. The contents of EAX indicate if BIST was successful. If EAX = 0000_0000h, BIST was successful.
If EAX is non-zero, BIST failed.
2. EDX contains the AMD-K6 processor signature, where X indicates the processor Stepping ID.
3. The contents of these registers are preserved following the recognition of INIT.
4. The CD and NW bits of CR0 are preserved following the recognition of INIT.
7.4
State of Processor After INIT
The recognition of the assertion of INIT causes the processor to
empty its pipelines, to initialize most of its internal state, and to
branch to address FFFF_FFF0h—the same instruction
execution starting point used after RESET. Unlike RESET, the
p r o c e s s o r p re s e rve s t h e c o n t e n t s o f i t s c a ch e s , t h e
floating-point state, the MMX state, MSRs, and the CD and NW
bits of the CR0 register.
The edge-sensitive interrupts FLUSH# and SMI# are sampled
and preserved during the INIT process and are handled
accordingly after the initialization is complete. However, the
processor resets any pending NMI interrupt upon sampling
INIT asserted.
INIT can be used as an accelerator for 80286 code that requires
a reset to exit from Protected mode back to Real mode.
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8
Cache Organization
The following sections describe the basic architecture and
resources of the AMD-K6 processor internal caches.
The performance of the AMD-K6 processor is enhanced by a
writeback level-one (L1) cache. The cache is organized as a
separate 32-Kbyte instruction cache and a 32-Kbyte data cache,
each with two-way set associativity (See Figure 67). The cache
line size is 32 bytes, and lines are prefetched from main memory
using an efficient, pipelined burst transaction. As the
instruction cache is filled, each instruction byte is analyzed for
instruction boundaries using predecode logic. Predecoding
annotates each instruction byte with information that later
enables the decoders to efficiently decode multiple instructions
simultaneously. Translation lookaside buffers (TLB) are also
used to translate linear addresses to physical addresses. The
instruction cache is associated with a 64-entry TLB while the
data cache is associated with a 128-entry TLB.
32-Kbyte Instruction Cache
Tag
RAM
Way 0
State Tag
Bit RA
Way 1
State
Bit
64-Entry TLB
System Bus
Interface Unit
Processor
Core
Pre-Decode Instruction Cache
128-Entry TLB
Tag
RAM
Way 0
MESI Tag
Bits RA
Way 1
MESI
Bits
32-Kbyte Data Cache
Figure 67. Cache Organization
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The processor cache design takes advantage of a sectored
organization (See Figure 68). Each sector consists of 64 bytes
configured as two 32-byte cache lines. The two cache lines of a
sector share a common tag but have separate MESI (modified,
exclusive, shared, invalid) bits that track the state of each cache
line.
Instruction Cache Line
Tag
Cache Line 1 Byte 31 Predecode Bits Byte 30 Predecode Bits ........
Address Cache Line 2 Byte 31 Predecode Bits Byte 30 Predecode Bits ........
........ Byte 0 Predecode Bits 1 MESI Bit
........ Byte 0 Predecode Bits 1 MESI Bit
Data Cache Line
Tag
Address
Cache Line 1
Byte 31
Byte 30
........
........
Byte 0
2 MESI Bits
Cache Line 2
Byte 31
Byte 30
........
........
Byte 0
2 MESI Bits
Note: Instruction-cache lines have only two coherency states (valid or invalid) rather than
the four MESI coherency states of data-cache lines. Only two states are needed for the
instruction cache because these lines are read-only.
Figure 68. Cache Sector Organization
8.1
MESI States in the Data Cache
The state of each line in the caches is tracked by the MESI bits.
The coherency of these states or MESI bits is maintained by
internal processor snoops and external inquiries by the system
logic. The following four states are defined for the data cache:
■
■
■
■
8.2
Modified—This line has been modified and is different from
main memory.
Exclusive—This line is not modified and is the same as main
memory. If this line is written to, it becomes Modified.
Shared—If a cache line is in the shared state it means that
the same line can exist in more than one cache system.
Invalid—The information in this line is not valid.
Predecode Bits
Decoding x86 instructions is particularly difficult because the
instructions vary in length, ranging from 1 to 15 bytes long.
Predecode logic supplies the predecode bits associated with
each instruction byte. The predecode bits indicate the number
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of bytes to the start of the next x86 instruction. The predecode
bits are passed with the instruction bytes to the decoders where
they assist with parallel x86 instruction decoding. The
predecode bits use memory separate from the 32-Kbyte
instruction cache. The predecode bits are stored in an extended
instruction cache alongside each x86 instruction byte as shown
in Figure 68 on page 172.
8.3
Cache Operation
The operating modes for the caches are configured by software
using the not writethrough (NW) and cache disable (CD) bits of
control register 0 (CR0 bits 29 and 30 respectively). These bits
are used in all operating modes.
When the CD and NW bits are both set to 0, the cache is fully
enabled. This is the standard operating mode for the cache. If a
read miss occurs when the processor reads from the cache, a
line fill takes place. Write hits to the cache are updated, while
write misses and writes to shared lines cause external memory
updates.
Note: A write allocate operation can modify the behavior of write
misses to the cache. See “Write Allocate” on page 177.
When CD is set to 0 and NW is set to 1, an invalid mode of
operation exists that causes a general protection fault to occur.
When CD is set to 1 (disabled) and NW is set to 0, the cache fill
mechanism is disabled but the contents of the cache are still
valid. The processor reads from the cache and, if a read miss
occurs, no line fills take place. Write hits to the cache are
updated, while write misses and writes to shared lines cause
external memory updates.
When the CD and NW bits are both set to 1, the cache is fully
disabled. Even though the cache is disabled, the contents are
not necessarily invalid. The processor reads from the cache and,
if a read miss occurs, no line fills take place. If a write hit
occurs, the cache is updated but an external memory update
does not occur. If a data line is in the exclusive state during a
write hit, the MESI bits are changed to the modified state.
Write misses access memory directly.
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The operating system can control the cacheability of a page.
The paging mechanism is controlled by CR3, the Page Directory
Entry (PDE), and the Page Table Entry (PTE). Within CR3,
PDE, and PTE are Page Cache Disable (PCD) and Page
Writethrough (PWT) bits. The values of the PCD and PWT bits
used in Table 27 through Table 29 are taken from either the PTE
or PDE. For more information see the descriptions of PCD and
PWT on pages 107 and 109, respectively.
Table 27 through Table 29 describe the logic that determines
the cacheability of a cycle and how that cacheability is affected
by the PCD bits, the PWT bits, the PG bit of CR0, the CD bit of
CR0, writeback cycles, the Cache Inhibit (CI) bit of Test
Register 12 (TR12), and unlocked memory reads.
Table 27 describes how the PWT signal is driven based on the
values of the PWT bits and the PG bit of CR0.
Table 27. PWT Signal Generation
PWT Bit*
PG Bit of CR0
PWT Signal
1
1
High
0
1
Low
1
0
Low
0
0
Low
Note:
* PWT is taken from PTE or PDE
Table 28 describes how the PCD signal is driven based on the
values of the CD bit of CR0, the PCD bits, and the PG bit of
CR0.
Table 28. PCD Signal Generation
CD Bit of CR0
PCD Bit*
PG Bit of CR0
PCD Signal
1
X
X
High
0
1
1
High
0
0
1
Low
0
1
0
Low
0
0
0
Low
Note:
* PCD is taken from PTE or PDE
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Table 29 describes how the CACHE# signal is driven based on
writeback cycles, the CI bit of TR12, unlocked memory reads,
and the PCD signal.
Table 29. CACHE# Signal Generation
Cache-Related Signals
CI Bit of TR12
1
X
X
X
Low
0
1
1
High
High
0
0
1
High
High
0
1
0
High
High
0
0
0
High
High
0
1
1
Low
High
0
0
1
Low
Low
0
1
0
Low
High
0
0
0
Low
High
Unlocked
PCD Signal
Memory Reads
CACHE#
Complete descriptions of the signals that control cacheability
and cache coherency are given on the following pages:
■
■
■
■
■
■
■
■
■
■
8.4
Writeback
Cycle
CACHE#—page 90
EADS#—page 94
FLUSH#—page 97
HIT#—page 98
HITM#—page 98
INV—page 102
KEN#—page 103
PCD—page 107
PWT—page 109
WB/WT#—page 116
Cache Disabling
To completely disable all cache accesses, the CD and NW bits
must be set to 1 and the cache must be completely flushed.
There are two different methods for flushing the cache. The
first method relies on the system logic and the second relies on
software.
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For the system logic to flush the cache, the processor must
sample FLUSH# asserted. In this method, the processor writes
back any data cache lines that are in the modified state,
invalidates all lines in the instruction and data caches, and then
executes a flush acknowledge special cycle (See Table 19 on
page 119).
Software can use two different instructions to flush the cache.
Both the WBINVD and INVD instructions cause all cache lines
to be marked invalid. The WBINVD instruction causes all
modified lines to first be written back to memory. The INVD
instruction invalidates all cache lines without writing modified
lines back to memory.
Any area of system memory can be cached. However, the
processor prevents caching of locked operations and TLB reads,
the operating system can prevent caching of certain pages by
setting the PCD and PWT bits in the PDE or PTE, and system
logic can prevent caching of certain bus cycles by negating the
KEN# input signal with the first BRDY# or NA# of a cycle.
8.5
Cache-Line Fills
When the CPU needs to read memory, the processor drives a
read cycle onto the bus. If the cycle is cacheable the CPU
asserts CACHE#. The system logic also has control of the
cacheability of bus cycles. If it determines the address is
cacheable, system logic asserts the KEN# signal and the
appropriate value of WB/WT#.
One of two events takes place next. If the cycle is not cacheable,
a non-pipelined, single-transfer read takes place. The processor
waits for the system logic to return the data and assert a single
BRDY# (See Figure 45 on page 127). If the cycle is cacheable,
the processor executes a 32-byte burst read cycle. The processor
expects to sample BRDY# asserted a total of four times for a
burst read cycle to take place (See Figure 47 on page 131).
Instruction-cache line fills initiate 32-byte transfers from
memory (one burst cycle) on the bus. Data-cache line fills also
initiate 32-byte transfers on the bus. If the data-cache line being
filled replaces a modified line, the prior contents of the line are
copied to a 32-byte writeback (copyback) buffer in the bus
interface unit while the new line is being read.
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8.6
Cache-Line Replacements
As programs execute and task switches occur, some cache lines
eventually require replacement.
Instruction cache lines are replaced using a Least Recently
Used (LRU) algorithm. If line replacement is required, lines are
replaced when read cache misses occur.
The data cache uses a slightly different approach to line
replacement. If a miss occurs, and a replacement is required,
lines are replaced by using a Least Recently Allocated (LRA)
algorithm.
Two forms of cache misses and associated cache fills can take
place—a sector replacement and a cache line replacement. In
the case of a sector replacement, the miss is due to a tag
mismatch, in which case the required cache line is filled from
external memory, and the cache line within the sector that was
not required is marked as invalid. In the case of a cache line
replacement, the address matches the tag, but the requested
cache line is marked as invalid. The required cache line is filled
from external memory, and the cache line within the sector that
is not required remains in the same cache state.
8.7
Write Allocate
Write allocate, if enabled, occurs when the processor has a
pending memory write cycle to a cacheable line and the line
does not currently reside in the L1 data cache. In this case, the
processor performs a burst read cycle to fetch the data-cache
line addressed by the pending write cycle. The data associated
w i t h t h e p e n d i n g w r i t e cy c l e i s m e r g e d w i t h t h e
recently-allocated data-cache line and stored in the processor’s
L1 data cache. The final MESI state of the cache line depends
on the state of the WB/WT# and PWT signals during the burst
read cycle and the subsequent cache write hit (See Table 30 on
page 182 to determine the cache-line states and the access
types following a cache read miss and cache write hit).
During write allocates, a 32-byte burst read cycle is executed in
place of a non-burst write cycle. While the burst read cycle
generally takes longer to execute than the write cycle,
performance gains are realized on subsequent write cycle hits
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to the write-allocated cache line. Due to the nature of software,
memory accesses tend to occur in proximity of each other
(principle of locality). The likelihood of additional write hits to
the write-allocated cache line is high.
The following is a description of three mechanisms by which the
AMD-K6 processor performs write allocations. A write allocate
is performed when any one or more of these mechanisms
indicates that a pending write is to a cacheable area of memory.
Write to a Cacheable
Page
Every time the processor performs a cache line fill, the address
of the page in which the cache line resides is saved in the
Cacheability Control Register (CCR). The page address of
subsequent write cycles is compared with the page address
stored in the CCR. If the two addresses are equal, then the
processor performs a write allocate because the page has
already been determined to be cacheable.
When the processor performs a cache line fill from a different
page than the address saved in the CCR, the CCR is updated
with the new page address.
Write to a Sector
If the address of a pending write cycle matches the tag address
of a valid cache sector, but the addressed cache line within the
sector is marked invalid (a sector hit but a cache line miss),
then the processor performs a write allocate. The pending write
cycle is determined to be cacheable because the sector hit
indicates the presence of at least one valid cache line in the
sector. The two cache lines within a sector are guaranteed by
design to be within the same page.
Write Allocate Limit
The Write Handling Control Register (WHCR) is a MSR that
contains three fields — the WCDE bit, the Write Allocate
Enable Limit (WAELIM) field, and the Write Allocate Enable
15-to-16-Mbyte (WAE15M) bit (See Figure 69 on page 179).
For proper functionality, always program the WCDE bit to 0.
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9
63
8
0
7
1
WAELIM
0
W
A
E
1
5
M
Reserved
Symbol
WCDE
WAELIM
WAE15M
Description
Bits
Always program to 0
8
Write Allocate Enable Limit
7–1
Write Allocate Enable 15-to-16-Mbyte 0
Note: Hardware RESET initializes this MSR to all zeros.
Figure 69. Write Handling Control Register (WHCR)
The WAELIM field is 7 bits wide. This field, multiplied by 4
Mbytes, defines an upper memory limit. Any pending write
cycle that addresses memory below this limit causes the
processor to perform a write allocate. Write allocate is disabled
for memory accesses at and above this limit unless the
processor determines a pending write cycle is cacheable by
means of one of the other write allocate mechanisms—Write to
a Cacheable Page and Write to a Sector. The maximum value of
this memory limit is ((27 – 1) · 4 Mbytes) = 508 Mbytes. When all
the bits in this field are set to 0, all memory is above this limit
and this mechanism for allowing write allocate is effectively
disabled.
The Write Allocate Enable 15-to-16-Mbyte (WAE15M) bit is
used to enable write allocations for the memory write cycles
that address the 1 Mbyte of memory between 15 Mbytes and 16
Mbytes. This bit must be set to 1 to allow write allocate in this
memory area. This bit is provided to account for a small number
of uncommon memory-mapped I/O adapters that use this
particular memory address space. If the system contains one of
these peripherals, the bit should be set to 0. The WAE15M bit is
ignored if the value in the WAELIM field is set to less than 16
Mbytes.
By definition a write allocate is never performed in the memory
area between 640 Kbytes and 1 Mbyte unless the processor
determines a pending write cycle is cacheable by means of one
of the other write allocate mechanisms—Write to a Cacheable
Page and Write to a Sector. It is not considered safe to perform
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write allocations between 640 Kbytes and 1 Mbyte (000A_0000h
to 000F_FFFFh) because it is considered a non-cacheable
region of memory.
Figure 70 shows the logic flow for all the mechanisms involved
with write allocate for memory bus cycles. The left side of the
diagram (the text) describes the conditions that need to be true
in order for the value of that line to be a 1. Items 1 to 3 of the
diagram are related to general cache operation and items 4 to
11 are related to the write allocate mechanisms.
Fo r m o re i n f o r m a t i o n a b o u t w r i t e a l l o c a t e , s e e t h e
Implementation of Write Allocate in the K86™ Processors
Application Note, order# 21326.
Perform
Write Allocate
1) CD Bit of CR0.
2) PCD Signal
3) CI Bit of TR12
4) Write to Cacheable Page (CCR)
5) Write to a Sector
6) WCDE Bit
7) Less Than Limit (WAELIM)
8) Between 640 Kbytes and 1 Mbyte
9) Between 15–16 Mbytes
10) Write Allocate Enable 15–16 Mbyte (WAE15M)
Figure 70. Write Allocate Logic Mechanisms and Conditions
Descriptions of the
Logic Mechanisms
and Conditions
1. CD Bit of CR0—When the cache disable (CD) bit within
control register 0 (CR0) is set to 1, the cache fill mechanism
for both reads and writes is disabled, therefore write
allocate does not occur.
2. PCD Signal—When the PCD (page cache disable) signal is
driven High, caching for that page is disabled even if KEN#
is sampled asserted, therefore write allocate does not occur.
3. CI Bit of TR12—When the cache inhibit bit of Test Register
12 is set to 1, the L1 caches are disabled, therefore write
allocate does not occur.
4. Write to a Cacheable Page (CCR)—A write allocate is
performed if the processor knows that a page is cacheable.
The CCR is used to store the page address of the last cache
fill for a read miss. See “Write to a Cacheable Page” on page
178 for a detailed description of this condition.
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5. Write to a Sector—A write allocate is performed if the
address of a pending write cycle matches the tag address of a
valid cache sector but the addressed cache line within the
sector is invalid. See “Write to a Sector” on page 178 for a
detailed description of this condition.
6. WCDE Bit—For proper functionality, always program bit 8
of WHCR to 0.
7. Less Than Limit (WAELIM)—The write allocate limit
mechanism determines if the memory area being addressed
is less than the limit set in the WAELIM field of WHCR. If
the address is less than the limit, write allocate for that
memory address is performed as long as conditions 9 and 10
do not prevent write allocate.
8. Between 640 Kbytes and 1 Mbyte —Write allocate is not
performed in the memory area between 640 Kbytes and 1
Mbyte. It is not considered safe to perform write allocations
between 640 Kbytes and 1 Mbyte (000A_0000h to
000F_FFFFh) because this area of memory is considered a
non-cacheable region of memory.
9. Between 15–16 Mbytes—If the address of a pending write
cycle is in the 1 Mbyte of memory between 15 Mbytes and 16
Mbytes, and the WAE15M bit is set to 1, write allocate for
this cycle is enabled.
10. Write Allocate Enable 15–16 Mbytes (WAE15M)—This
condition is associated with the Write Allocate Limit
mechanism and affects write allocate only if the limit
specified by the WAELIM field is greater than or equal to 16
Mbytes. If the memory address is between 15 Mbytes and 16
Mbytes, and the WAE15M bit in the WHCR is set to 0, write
allocate for this cycle is disabled.
8.8
Prefetching
The AMD-K6 processor performs instruction cache prefetching
for sector replacements only — as opposed to cache-line
replacements. The cache prefetching results in the filling of the
required cache line first, and a prefetch of the second cache line
making up the other half of the sector. Furthermore, the
prefetch of the second cache line is initiated only in the forward
direction—that is, only if the requested cache line is the first
position within the sector. From the perspective of the external
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bus, the two cache-line fills typically appear as two 32-byte
burst read cycles occurring back-to-back or, if allowed, as
p i p e l in e d cy c le s . The b u rst re a d cy c l e s d o n o t o c c u r
back-to-back (wait states occur) if the processor is not ready to
start a new cycle, if higher priority data read or write requests
exist, or if NA# (next address) was sampled negated. Wait states
can also exist between burst cycles if the processor samples
AHOLD or BOFF# asserted.
8.9
Cache States
Table 30 shows all the possible cache-line states before and
after program-generated accesses to individual cache lines. The
table includes the correspondence between MESI states and
writethrough or writeback states for lines in the data cache.
Table 30. Data Cache States for Read and Write Accesses
Type
Read Miss
Cache
Read
Cache
Write
Cache State After Access
Cache State Before
Access
Access
Type1
MESI State
Writeback
Writethrough State
invalid
single read
invalid
–
invalid
burst read2
(cacheable)
shared or
exclusive3
writethrough or
writeback3
Read
Hit
shared
–
shared
writethrough
exclusive
–
exclusive
writeback
modified
–
modified
writeback
Write Miss
invalid
single write4
invalid
–
shared
cache update and
single write
shared or
exclusive3
writethrough or
writeback3
exclusive or modified
cache update
modified
writeback
Write Hit
Notes:
1.
2.
3.
4.
Single read, single write, cache update, and writethrough = 1 to 8 bytes. Line fill = 32-byte burst read.
If CACHE# is driven Low and KEN# is sampled asserted.
If PWT is driven Low and WB/WT# is sampled High, the line is cached in the exclusive (writeback) state.
A write cycle occurs only if the write allocate conditions as specified in “Write Allocate” on page 177 are not met.
– Not applicable or none.
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8.10
Cache Coherency
Different ways exist to maintain coherency between the system
memory and cache memories. Inquire cycles, internal snoops,
FLUSH#, WBINVD, INVD, and line replacements all prevent
inconsistencies between memories.
Inquire Cycles
Inquire cycles are bus cycles initiated by system logic. These
inquiries ensure coherency between the caches and main
memory. In systems with multiple caching masters, system logic
maintains cache coherency by driving inquire cycles to the
processor. System logic initiates inquire cycles by asserting
AHOLD, BOFF#, or HOLD to obtain control of the address bus
and then driving EADS#, INV (optional), and an inquire
address (A[31:5]). This type of bus cycle causes the processor to
compare the tags for both its instruction and data caches with
the inquire address. If there is a hit to a shared or exclusive line
in the data cache or a valid line in the instruction cache, the
processor asserts HIT#. If the compare hits a modified line in
the data cache, the processor asserts HIT# and HITM#. If
HITM# is asserted, the processor writes the modified line back
to memory. If INV was sampled asserted with EADS#, a hit
invalidates the line. If INV was sampled negated with EADS#, a
hit leaves the line in the shared state or transitions it from the
exclusive or modified to shared state.
Internal Snooping
Internal snooping is initiated by the processor (rather than
system logic) during certain cache accesses. It is used to
maintain coherency between the L1 instruction and data
caches.
The processor automatically snoops its instruction cache during
read or write misses to its data cache, and it snoops its data
cache during read misses to its instruction cache. Table 31 on
page 185 summarizes the actions taken during this internal
snooping.
If an internal snoop hits its target, the processor does the
following:
■
Chapter 8
Data cache snoop during an instruction-cache read miss—If
modified, the line in the data cache is written back to
memory. Regardless of its state, the data-cache line is
invalidated and the instruction cache performs a burst cycle
read from memory.
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■
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Instruction cache snoop during a data cache miss—The line in
the instruction cache is marked invalid, and the data-cache
read or write is performed from memory.
FLUSH#
In response to sampling FLUSH# asserted, the processor writes
back any data cache lines that are in the modified state and
then marks all lines in the instruction and data caches as
invalid.
WBINVD and INVD
These x86 instructions cause all cache lines to be marked as
invalid. WBINVD writes back modified lines before marking all
cache lines invalid. INVD does not write back modified lines.
Cache-Line
Replacement
Replacing lines in the instruction or data cache, according to
the line replacement algorithms described in “Cache-Line
Fills” on page 176, ensures coherency between main memory
and the caches.
Table 31 on page 185 shows all possible cache-line states before
and after cache snoop or invalidation operations performed
with inquire cycles. This table shows all of the conditions for
writethroughs and writebacks to memory.
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Table 31. Cache States for Inquiries, Snoops, Invalidation, and Replacement
Type of Operation
Inquire
Cycle
Internal
Snoop
FLUSH#
Signal
WBINVD
Instruction
INVD
Instruction
Cache-Line
Replacement
Cache State After Operation
Cache State
Before Operation
Memory Access
shared or
exclusive
–
modified
burst write
(writeback)
shared or
exclusive
–
modified
burst write
(writeback)
shared or
exclusive
–
modified
burst write
(writeback)
shared or
exclusive
–
modified
burst write
(writeback)
–
–
shared or
exclusive
–
modified
burst write
(writeback)
MESI State
Writeback
Writethrough State
INV=0
shared
writethrough
INV=1
invalid
invalid
INV=0
shared
writethrough
INV=1
invalid
invalid
invalid
invalid
invalid
invalid
invalid
invalid
invalid
invalid
See Table 30
Notes:
All writebacks are 32-byte burst write cycles.
– Not applicable or none.
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Cache Snooping
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Table 32 shows the conditions under which snooping occurs in
the AMD-K6 processor and the resources that are snooped.
Table 32. Snoop Action
Snooping Action
Type of Event
Type of Access
Instruction
Cache
Data Cache
Inquire Cycle
System Logic
yes1
yes1
Read
Miss
–
yes2
Read
Hit
–
no
Read
Miss
yes3
–
Read
Hit
no
–
Write
Miss
yes3
–
Write
Hit
no
–
Instruction
Cache
Internal Snoop
Data
Cache
Notes:
1. The processor’s response to an inquire cycle depends on the state of the INV input signal
and the state of the cache line as follows:
For the instruction cache, if INV is sampled negated, the line remains invalid or valid, but
if INV is sampled asserted, the line is invalidated.
For the data cache, if INV is sampled negated, valid lines remain in or transition to the
shared state, a modified data cache line is written back before the line is marked shared
(with HITM# asserted), and invalid lines remain invalid. For the data cache, if INV is
sampled asserted, the line is marked invalid. Modified lines are written back before
invalidation.
2. If an internal snoop hits a modified line in the data cache, the line is written back and
invalidated. Then the instruction cache performs a burst read from memory.
3. If an internal snoop hits a line in the instruction cache, the instruction cache line is
invalidated and the data-cache read or write is performed from memory.
– Not applicable.
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8.11
Writethrough vs. Writeback Coherency States
The terms writethrough and writeback apply to two related
concepts in a read-write cache like the AMD-K6 processor L1
data cache. The following conditions apply to both the
writethrough and writeback modes:
■
■
8.12
Memory Writes—A relationship exists between external
memory writes and their concurrence with cache updates:
• An external memory write that occurs concurrently with
a cache update to the same location is a writethrough.
Writethroughs are driven as single cycles on the bus.
• An external memory write that occurs after the processor
has modified a cache line is a writeback. Writebacks are
driven as burst cycles on the bus.
Coherency State—A relationship exists between MESI
coherency states and writethrough-writeback coherency
states of lines in the cache as follows:
• Shared MESI lines are in the writethrough state.
• Modified and exclusive MESI lines are in the writeback
state.
A20M# Masking of Cache Accesses
Although the processor samples A20M# as a level-sensitive
input on every clock edge, it should only be asserted in Real
mode. The CPU applies the A20M# masking to its tags, through
which all programs access the caches. Therefore, assertion of
A20M# affects all addresses (cache and external memory),
including the following:
■
■
Cache-line fills (caused by read misses)
Cache writethroughs (caused by write misses or write hits to
lines in the shared state)
However, A20M# does not mask writebacks or invalidations
caused by the following actions:
■
■
■
■
Chapter 8
Internal snoops
Inquire cycles
The FLUSH# signal
The WBINVD instruction
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9
Floating-Point and Multimedia Execution Units
9.1
Floating-Point Execution Unit
The AMD-K6 processor contains an IEEE 754-compatible and
854-compatible floating-point execution unit designed to
accelerate the performance of software that utilizes the x86
floating-point instruction set. Floating-point software is
typically written to manipulate numbers that are very large or
very small, that require a high degree of precision, or that result
f r o m c o m p l e x m a t h e m a t i c a l o p e ra t i o n s s u c h a s
transce ndentals. Applications t hat t ake advantage of
floating-point operations include geometric calculations for
graphics acceleration, scientific, statistical, and engineering
applications, and business applications that use large amounts
of high-precision data.
The high-performance floating-point execution unit contains an
adder unit, a multiplier unit, and a divide/square root unit.
These low-latency units can execute floating-point instructions
in as few as two processor clocks. To increase performance, the
proce sso r is de sig ned to simul ta neo usly de code mo st
floating-point instructions with most short-decodeable
instructions.
See “Software Environment” on page 21 for a description of the
floating-point data types, registers, and instructions.
Handling
Floating-Point
Exceptions
The AMD-K6 processor provides the following two types of
exception handling for floating-point exceptions:
■
■
External Logic
Support of
Floating-Point
Exceptions
Chapter 9
If the numeric error (NE) bit in CR0 is set to 1, the processor
invokes the interrupt 10h handler. In this manner, the
floating-point exception is completely handled by software.
If the NE bit in CR0 is set to 0, the processor requires
external logic to generate an interrupt on the INTR signal in
order to handle the exception.
The processor provides the FERR# (Floating-Point Error) and
IGNNE# (Ignore Numeric Error) signals to allow the external
logic to generate the interrupt in a manner consistent with
IBM-compatible PC/AT systems. The assertion of FERR#
indicates the occurrence of an unmasked floating-point
exception resulting from the execution of a floating-point
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instruction. IGNNE# is used by the external hardware to control
the effect of an unmasked floating-point exception. Under
certain circumstances, if IGNNE# is sampled asserted, the
processor ignores the floating-point exception.
Figure 71 illustrates an implementation of external logic for
supporting floating-point exceptions. The following example
explains the operation of the external logic in Figure 71:
As the result of a floating-point exception, the processor
asserts FERR#. The assertion of FERR# and the
sampling of IGNNE# negated indicates the processor has
stopped instruction execution and is waiting for an
interrupt. The assertion of FERR# leads to the assertion
of INTR by the interrupt controller. The processor
a ck n o w l e d g e s t h e i n t e r r u p t a n d j u m p s t o t h e
corresponding interrupt service routine in which an I/O
write cycle to address port F0h leads to the assertion of
IGNNE#. When IGNNE# is sampled asserted, the
processor ignores the floating-point exception and
continues instruction execution. When the processor
negates FERR#, the external logic negates IGNNE#.
See “FERR# (Floating-Point Error)” on page 96 and “IGNNE#
(Ignore Numeric Exception)” on page 100 for more details.
AMD-K6®
Processor
I/O Address
Port F0h
IGNNE#
Flip-Flop
CLOCK Q
RESET
“1”
FERR#
DATA
Q
CLEAR
FERR#
Flip-Flop
CLOCK Q
DATA
Interrupt
Controller
IRQ13
Q
CLEAR
INTR
IGNNE#
Figure 71. External Logic for Supporting Floating-Point Exceptions
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9.2
Multimedia Execution Unit
The multimedia execution unit of the AMD-K6 processor is
designed to accelerate the performance of software written
using the industry-standard MMX instructions. Applications
that can take advantage of the MMX instructions include
graphics, video and audio compression and decompression,
speech recognition, and telephony applications.
The multimedia execution unit can execute MMX instructions
in a single processor clock. To increase performance, the
processor is designed to simultaneously decode all MMX
instructions with most other instructions.
For more information on MMX instructions, refer to AMD-K6®
Processor Multimedia Technology, order# 20726.
9.3
Floating-Point and MMX™ Instruction Compatibility
Registers
T h e e i g h t 6 4 -b i t M M X re g i s t e rs a re m a p p e d o n t h e
floating-point stack. This enables backward compatibility with
all existing software. For example, the register saving event
that is performed by operating systems during task switching
requires no changes to the operating system. The same support
provided in an operating system’s interrupt 7 handler (Device
Not Available) for saving and restoring the floating-point
registers also supports saving and restoring the MMX registers.
Exceptions
There are no new exceptions defined for supporting the MMX
instructions. All exceptions that occur while decoding or
executing an MMX instruction are handled in existing
exception handlers without modification.
FERR# and IGNNE#
MMX instructions do not generate floating-point exceptions.
However, if an unmasked floating-point exception is pending,
the processor asserts FERR# at the instruction boundary of the
next floating-point instruction, MMX instruction, or WAIT
instruction.
The sampling of IGNNE# asserted only affects processor
o p e ra t i o n d u r i n g t h e ex e c u t i o n o f a n e r ro r -s e n s i t ive
floating-point instruct ion, MMX inst ruct ion, or WAIT
instruction when the NE bit in CR0 is set to 0.
Chapter 9
Floating-Point and Multimedia Execution Units
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Chapter 9
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AMD-K6® Processor Data Sheet
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10
10.1
System Management Mode (SMM)
Overview
SMM is an alternate operating mode entered by way of a system
management interrupt (SMI#) and handled by an interrupt
service routine. SMM is designed for system control activities
s u ch a s p owe r m a n a g e m e n t . Th e s e a c t iv i t i e s a p p e a r
transparent to conventional operating systems like DOS and
Windows. SMM is primarily targeted for use by the Basic Input
Output System (BIOS) and specialized low-level device drivers.
The code and data for SMM are stored in the SMM memory
area, which is isolated from main memory.
The processor enters SMM by the system logic’s assertion of the
SMI# interrupt and the processor’s acknowledgment by the
assertion of SMIACT#. At this point the processor saves its state
into the SMM memory state-save area and jumps to the SMM
service routine. The processor returns from SMM when it
executes the RSM (resume) instruction from within the SMM
service routine. Subsequently, the processor restores its state
from the SMM save area, negates SMIACT#, and resumes
execution with the instruction following the point where it
entered SMM.
The following sections summarize the SMM state-save area,
entry into and exit from SMM, exceptions and interrupts in
SMM, memory allocation and addressing in SMM, and the SMI#
and SMIACT# signals.
10.2
SMM Operating Mode and Default Register Values
The software environment within SMM has the following
characteristics:
■
■
■
■
Chapter 10
Addressing and operation in Real mode
4-Gbyte segment limits
Default 16-bit operand, address, and stack sizes, although
instruction prefixes can override these defaults
Control transfers that do not override the default operand
size truncate the EIP to 16 bits
System Management Mode (SMM)
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■
■
■
■
■
■
■
20695H/0—March 1998
Far jumps or calls cannot transfer control to a segment with
a base address requiring more than 20 bits, as in Real mode
segment-base addressing
A20M# is masked
Interrupt vectors use the Real-mode interrupt vector table
The IF flag in EFLAGS is cleared (INTR not recognized)
The TF flag in EFLAGS is cleared
The NMI and INIT interrupts are disabled
Debug register DR7 is cleared (debug traps disabled)
Figure 72 on page 195 shows the default map of the SMM
me mo ry a rea . I t consis ts o f a 64 -Kbyt e area, bet wee n
0003_0000h and 0003_FFFFh, of which the top 32 Kbytes
(0003_8000h to 0003_FFFFh) must be populated with RAM.
The default code-segment (CS) base address for the area —
called the SMM base address —is at 0003_0000h. The top 512
bytes (0003_FE00h to 0003_FFFFh) contain a fill-down SMM
state-save area. The default entry point for the SMM service
routine is 0003_8000h.
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Fill Down
SMM
State-Save
Area
0003_FFFFh
0003_FE00h
32-Kbyte
Minimum RAM
SMM
Service Routine
Service Routine Entry Point
0003_8000h
SMM Base Address (CS)
0003_0000h
Figure 72. SMM Memory
Table 33 shows the initial state of registers when entering SMM.
Table 33. Initial State of Registers in SMM
Registers
Chapter 10
SMM Initial State
General Purpose Registers
unmodified
EFLAGs
0000_0002h
CR0
PE, EM, TS, and PG are cleared (bits 0, 2, 3,
and 31). The other bits are unmodified.
DR7
0000_0400h
GDTR, LDTR, IDTR, TSSR, DR6
unmodified
EIP
0000_8000h
CS
0003_0000h
DS, ES, FS, GS, SS
0000_0000h
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SMM State-Save Area
When the processor acknowledges an SMI# interrupt by
asserting SMIACT#, it saves its state in a 512-byte SMM
state-save area shown in Table 34. The save begins at the top of
the SMM memory area (SMM base address + FFFFh) and fills
down to SMM base address + FE00h.
Table 34 shows the offsets in the SMM state-save area relative
to the SMM base address. The SMM service routine can alter
any of the read/write values in the state-save area.
Table 34. SMM State-Save Area Map
Address Offset
Contents Saved
FFFCh
CR0
FFF8h
CR3
FFF4h
EFLAGS
FFF0h
EIP
FFECh
EDI
FFE8h
ESI
FFE4h
EBP
FFE0h
ESP
FFDCh
EBX
FFD8h
EDX
FFD4h
ECX
FFD0h
EAX
FFCCh
DR6
FFC8h
DR7
FFC4h
TR
FFC0h
LDTR Base
FFBCh
GS
FFB8h
FS
FFB4h
DS
FFB0h
SS
FFACh
CS
FFA8h
ES
Notes:
— No data dump at that address
* Only contains information if SMI# is asserted during a valid I/O bus cycle.
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Table 34. SMM State-Save Area Map (continued)
Address Offset
Contents Saved
FFA4h
I/O Trap Dword
FFA0h
—
FF9Ch
I/O Trap EIP*
FF98h
—
FF94h
—
FF90h
IDT Base
FF8Ch
IDT Limit
FF88h
GDT Base
FF84h
GDT Limit
FF80h
TSS Attr
FF7Ch
TSS Base
FF78h
TSS Limit
FF74h
—
FF70h
LDT High
FF6Ch
LDT Low
FF68h
GS Attr
FF64h
GS Base
FF60h
GS Limit
FF5Ch
FS Attr
FF58h
FS Base
FF54h
FS Limit
FF50h
DS Attr
FF4Ch
DS Base
FF48h
DS Limit
FF44h
SS Attr
FF40h
SS Base
FF3Ch
SS Limit
FF38h
CS Attr
FF34h
CS Base
FF30h
CS Limit
FF2Ch
ES Attr
Notes:
— No data dump at that address
* Only contains information if SMI# is asserted during a valid I/O bus cycle.
Chapter 10
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Table 34. SMM State-Save Area Map (continued)
Address Offset
Contents Saved
FF28h
ES Base
FF24h
ES Limit
FF20h
—
FF1Ch
—
FF18h
—
FF14h
CR2
FF10h
CR4
FF0Ch
I/O restart ESI*
FF08h
I/O restart ECX*
FF04h
I/O restart EDI*
FF02h
HALT Restart Slot
FF00h
I/O Trap Restart Slot
FEFCh
SMM RevID
FEF8h
SMM BASE
FEF7h–FE00h
—
Notes:
— No data dump at that address
* Only contains information if SMI# is asserted during a valid I/O bus cycle.
10.4
SMM Revision Identifier
The SMM revision identifier at offset FEFCh in the SMM
state-save area specifies the version of SMM and the extensions
that are available on the processor. The SMM revision identifier
fields are as follows:
■
■
■
■
Bits 31–18—Reserved
Bit 17—SMM base address relocation (1 = enabled)
Bit 16—I/O trap restart (1 = enabled)
Bits 15–0—SMM revision level for the AMD-K6 processor =
0002h
Table 35 on page 199 shows the format of the SMM Revision
Identifier.
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Table 35. SMM Revision Identifier
10.5
31–18
17
16
15–0
Reserved
SMM Base Relocation
I/O Trap Extension
SMM Revision Level
0
1
1
0002h
SMM Base Address
During RESET, the processor sets the base address of the
code-segment (CS) for the SMM memory area—the SMM base
address—to its default, 0003_0000h. The SMM base address at
offset FEF8h in the SMM state-save area can be changed by the
SMM service routine to any address that is aligned to a
32-Kbyte boundary. (Locations not aligned to a 32-Kbyte
boundary cause the processor to enter the Shutdown state when
executing the RSM instruction.)
In some operating environments it may be desirable to relocate
the 64-Kbyte SMM memory area to a high memory area in order
to provide more low memory for legacy software. During system
initialization, the base of the 64-Kbyte SMM memory area is
relocated by the BIOS. To relocate the SMM base address, the
system enters the SMM handler at the default address. This
handler changes the SMM base address location in the SMM
state-save area, copies the SMM handler to the new location,
and exits SMM.
The next time SMM is entered, the processor saves its state at
the new base address. This new address is used for every SMM
entry until the SMM base address in the SMM state-save area is
changed or a hardware reset occurs.
10.6
Halt Restart Slot
During entry into SMM, the halt restart slot at offset FF02h in
the SMM state-save area indicates if SMM was entered from the
Halt state. Before returning from SMM, the halt restart slot
(offset FF02h) can be written to by the SMM service routine to
specify whether the return from SMM takes the processor back
to the Halt state or to the next instruction after the HLT
instruction.
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Upon entry into SMM, the halt restart slot is defined as follows:
■
■
Bits 15–1—Reserved
Bit 0—Point of entry to SMM:
1 = entered from Halt state
0 = not entered from Halt state
After entry into the SMI handler and before returning from
SMM, the halt restart slot can be written using the following
definition:
■
■
Bits 15–1—Reserved
Bit 0—Point of return when exiting from SMM:
1 = return to Halt state
0 = return to next instruction after the HLT instruction
If the return from SMM takes the processor back to the Halt
state, the HLT instruction is not re-executed, but the Halt
special bus cycle is driven on the bus after the return.
10.7
I/O Trap Dword
If the assertion of SMI# is recognized during the execution of an
I/O instruction, the I/O trap dword at offset FFA4h in the SMM
state-save area contains information about the instruction. The
fields of the I/O trap dword are configured as follows:
■
■
■
■
■
■
Bits 31–16—I/O port address
Bits 15–4—Reserved
Bit 3—REP (repeat) string operation (1 = REP string, 0 = not
a REP string)
Bit 2—I/O string operation (1 = I/O string, 0 = not an I/O
string)
Bit 1—Valid I/O instruction (1 = valid, 0 = invalid)
Bit 0—Input or output instruction (1 = INx, 0 = OUTx)
Table 36 shows the format of the I/O trap dword.
Table 36. I/O Trap Dword Configuration
200
31—16
15—4
3
2
1
0
I/O Port
Address
Reserved
REP String
Operation
I/O String
Operation
Valid I/O
Instruction
Input or
Output
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The I/O trap dword is related to the I/O trap restart slot (see “I/O
Trap Restart Slot”). If bit 1 of the I/O trap dword is set by the
processor, it means that SMI# was asserted during the
execution of an I/O instruction. The SMI handler tests bit 1 to
see if there is a valid I/O instruction trapped. If the I/O
instruction is valid, the SMI handler is required to ensure the
I/O trap restart slot is set properly. The I/O trap restart slot
informs the CPU whether it should re-execute the I/O
instruction after the RSM or execute the instruction following
the trapped I/O instruction.
Note: If SMI# is sampled asserted during an I/O bus cycle a
minimum of three clock edges before BRDY# is sampled
asserted, the associated I/O instruction is guaranteed to be
trapped by the SMI handler.
10.8
I/O Trap Restart Slot
The I/O trap restart slot at offset FF00h in the SMM state-save
area specifies whether the trapped I/O instruction should be
re-executed on return from SMM. This slot in the state-save area
is called the I/O instruction restart function. Re-executing a
trapped I/O instruction is useful, for example, if an I/O write
occurs to a disk that is powered down. The system logic
monitoring such an access can assert SMI#. Then the SMM
service routine would query the system logic, detect a failed I/O
write, take action to power-up the I/O device, enable the I/O
trap restart slot feature, and return from SMM.
The fields of the I/O trap restart slot are defined as follows:
■
■
Bits 31–16—Reserved
Bits 15–0—I/O instruction restart on return from SMM:
0000h = execute the next instruction after the trapped
I/O instruction
00FFh = re-execute the trapped I/O instruction
Table 37 shows the format of the I/O trap restart slot.
Table 37. I/O Trap Restart Slot
31–16
15–0
I/O Instruction restart on return from SMM:
Reserved
Chapter 10
■
0000h = execute the next instruction after the trapped I/O
■
00FFh = re-execute the trapped I/O instruction
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The processor initializes the I/O trap restart slot to 0000h upon
entry into SMM. If SMM was entered due to a trapped I/O
instruction, the processor indicates the validity of the I/O
instruction by setting or clearing bit 1 of the I/O trap dword at
offset FFA4h in the SMM state-save area. The SMM service
routine should test bit 1 of the I/O trap dword to determine if a
valid I/O instruction was being executed when entering SMM
and before writing the I/O trap restart slot. If the I/O instruction
is valid, the SMM service routine can safely rewrite the I/O trap
restart slot with the value 00FFh, which causes the processor to
re-execute t he trapped I/O instruction w hen the RSM
instruction is executed. If the I/O instruction is invalid, writing
the I/O trap restart slot has undefined results.
If a second SMI# is asserted and a valid I/O instruction was
trapped by the first SMM handler, the CPU services the second
SMI# prior to re-executing the trapped I/O instruction. The
second entry into SMM never has bit 1 of the I/O trap dword set,
and the second SMM service routine must not rewrite the I/O
trap restart slot.
During a simultaneous SMI# I/O instruction trap and debug
breakpoint trap, the AMD-K6 processor first responds to the
SMI# and postpones recognizing the debug exception until
after returning from SMM via the RSM instruction. If the debug
registers DR3–DR0 are used while in SMM, they must be saved
and restored by the SMM handler. The processor automatically
saves and restores DR7–DR6. If the I/O trap restart slot in the
SMM state-save area contains the value 00FFh when the RSM
instruction is executed, the debug trap does not occur until
after the I/O instruction is re-executed.
10.9
Exceptions, Interrupts, and Debug in SMM
During an SMI# I/O trap, the exception/interrupt priority of the
AMD-K6 processor changes from its normal priority. The
normal priority places the debug traps at a priority higher than
the sampling of the FLUSH# or SMI# signals. However, during
an SMI# I/O trap, the sampling of the FLUSH# or SMI# signals
takes precedence over debug traps.
The processor recognizes the assertion of NMI within SMM
immediately after the completion of an IRET instruction. Once
NMI is recognized within SMM, NMI recognition remains
enabled until SMM is exited, at which point NMI masking is
restored to the state it was in before entering SMM.
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11
Test and Debug
The AMD-K6 processor implements various test and debug
modes to enable the functional and manufacturing testing of
systems and boards that use the processor. In addition, the
debug features of the processor allow designers to debug the
instruction execution of software components. This chapter
describes the following test and debug features:
■
Built-In Self-Test (BIST)—The BIST, which is invoked after
the falling transition of RESET, runs internal tests that
exercise most on-chip RAM structures.
■
Tri-State Test Mode—A test mode that causes the processor
to float its output and bidirectional pins.
Boundary-Scan Test Access Port (TAP)—The Joint Test Action
Group (JTAG) test access function defined by the IEEE
Standard Test Access Port and Boundary-Scan Architecture
(IEEE 1149.1-1990) specification.
Level-One (L1) Cache Inhibit—A feature that disables the
processor’s internal L1 instruction and data caches.
Debug Support—Consists of all x86-compatible software
debug features, including the debug extensions.
■
■
■
11.1
Built-In Self-Test (BIST)
Following the falling transition of RESET, the processor
unconditionally runs its BIST. The internal resources tested
during BIST include the following:
■
■
L1 instruction and data caches
Instruction and Data Translation Lookaside Buffers (TLBs)
The contents of the EAX general-purpose register after the
completion of reset indicate if the BIST was successful. If EAX
contains 0000_0000h, then BIST was successful. If EAX is
non-zero, the BIST failed. Following the completion of the BIST,
the pro ce ssor jum ps to address FF FF_FF F0 h to start
instruction execution, regardless of the outcome of the BIST.
The BIST takes approximately 295,000 processor clocks to
complete.
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Tri-State Test Mode
The Tri-State Test mode causes the processor to float its output
and bidirectional pins, which is useful for board-level
manufacturing testing. In this mode, the processor is
electrically isolated from other components on a system board,
allowing automated test equipment (ATE) to test components
that drive the same signals as those the processor floats.
If the FLUSH# signal is sampled Low during the falling
transition of RESET, the processor enters the Tri-State Test
mode. (See “FLUSH# (Cache Flush)” on page 97 for the
specific sampling requirements.) The signals floated in the
Tri-State Test mode are as follows:
■
■
■
■
■
■
■
■
A[31:3]
ADS#
ADSC#
AP
APCHK#
BE[7:0]#
BREQ
CACHE#
■
■
■
■
■
■
■
■
D/C#
D[63:0]
DP[7:0]
FERR#
HIT#
HITM#
HLDA
LOCK#
■
■
■
■
■
■
■
M/IO#
PCD
PCHK#
PWT
SCYC
SMIACT#
W/R#
The VCC2DET and TDO signals are the only outputs not
floated in the Tri-State Test mode. VCC2DET must remain Low
to ensure the system continues to supply the specified
processor core voltage to the VCC2 pins. TDO is never floated
because the Boundary-Scan Test Access Port must remain
enabled at all times, including during the Tri-State Test mode.
The Tri-State Test mode is exited when the processor samples
RESET asserted.
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11.3
Boundary-Scan Test Access Port (TAP)
The boundary-scan Test Access Port (TAP) is an IEEE standard
that defines synchronous scanning test methods for complex
logic circuits, such as boards containing a processor. The
AMD-K6 processor supports the TAP standard defined in the
IEEE Standard Test Access Port and Boundary-Scan Architecture
(IEEE 1149.1-1990) specification.
Boundary scan testing uses a shift register consisting of the
serial interconnection of boundary-scan cells that correspond
to each I/O buffer of the processor. This non-inverting register
chain, called a Boundary Scan Register (BSR), can be used to
capture the state of every processor pin and to drive every
processor output and bidirectional pin to a known state.
Each BSR of every component on a board that implements the
boundary-scan architecture can be serially interconnected to
enable component interconnect testing.
Test Access Port
The TAP consists of the following:
■
■
■
TAP Signals
The test signals associated with the TAP controller are as
follows:
■
Chapter 11
Test Access Port (TAP) Controller—The TAP controller is a
synchronous, finite state machine that uses the TMS and
TDI input signals to control a sequence of test operations.
See “TAP Controller State Machine” on page 212 for a list
of TAP states and their definition.
Instruction Register (IR)—The IR contains the instructions
that select the test operation to be performed and the Test
Data Register (TDR) to be selected. See “TAP Registers” on
page 206 for more details on the IR.
Test Data Registers (TDR)—The three TDRs are used to
process the test data. Each TDR is selected by an
instruction in the Instruction Register (IR). See “TAP
Registers” on page 206 for a list of these registers and their
functions.
TCK—The Test Clock for all TAP operations. The rising edge
of TCK is used for sampling TAP signals, and the falling
edge of TCK is used for asserting TAP signals. The state of
the TMS signal sampled on the rising edge of TCK causes
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■
■
■
■
20695H/0—March 1998
the state transitions of the TAP controller to occur. TCK can
be stopped in the logic 0 or 1 state.
TDI—The Test Data Input represents the input to the most
significant bit of all TAP registers, including the IR and all
test data registers. Test data and instructions are serially
shifted by one bit into their respective registers on the rising
edge of TCK.
TDO—The Test Data Output represents the output of the
least significant bit of all TAP registers, including the IR and
all test data registers. Test data and instructions are serially
shifted by one bit out of their respective registers on the
falling edge of TCK.
TMS—The Test Mode Select input specifies the test
function and sequence of state changes for boundary-scan
testing. If TMS is sampled High for five or more consecutive
clocks, the TAP controller enters its reset state.
TRST#—The Test Reset signal is an asynchronous reset that
unconditionally causes the TAP controller to enter its reset
state.
Refer to “Electrical Data” on page 233 and “Signal Switching
Charac teristics” on page 241 to obtain t he electrical
specifications of the test signals.
TAP Registers
The AMD-K6 processor provides an Instruction Register (IR)
a n d t h re e Te s t D a t a R e g i s t e rs ( T D R ) t o s u p p o r t t h e
boundary-scan architecture. The IR and one of the TDRs—the
Boundary-Scan Register (BSR)—consist of a shift register and
an output register. The shift register is loaded in parallel in the
Capture states. (See “TAP Controller State Machine” on page
212 for a description of the TAP controller states.) In addition,
the shift register is loaded and shifted serially in the Shift
states. The output register is loaded in parallel from its
corresponding shift register in the Update states.
Instruction Register (IR). The IR is a 5-bit register, without parity,
that determines which instruction to run and which test data
register to select. When the TAP controller enters the
Capture-IR state, the processor loads the following bits into the
IR shift register:
■
■
206
01b—Loaded into the two least significant bits, as specified
by the IEEE 1149.1 standard
000b—Loaded into the three most significant bits
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Lo a d ing 0 00 01 b int o t h e I R sh if t re g ist e r d u rin g t h e
Capture-IR state results in loading the SAMPLE/PRELOAD
instruction.
For each entry into the Shift-IR state, the IR shift register is
serially shifted by one bit toward the TDO pin. During the shift,
the most significant bit of the IR shift register is loaded from
the TDI pin.
The IR output register is loaded from the IR shift register in the
Update-IR state, and the current instruction is defined by the IR
output register. See “TAP Instructions” on page 211 for a list and
definition of the instructions supported by the AMD-K6.
Boundary Scan Register (BSR). The BSR is a Test Data Register
consisting of the interconnection of 152 boundary-scan cells.
Each output and bidirectional pin of the processor requires a
two-bit cell, where one bit corresponds to the pin and the other
bit is the output enable for the pin. When a 0 is shifted into the
enable bit of a cell, the corresponding pin is floated, and when
a 1 is shifted into the enable bit, the pin is driven valid. Each
input pin requires a one-bit cell that corresponds to the pin.
The last cell of the BSR is reserved and does not correspond to
any processor pin.
The total number of bits that comprise the BSR is 281. Table 38
on page 209 lists the order of these bits, where TDI is the input
to bit 280, and TDO is driven from the output of bit 0. The
entries listed as pin_E (where pin is an output or bidirectional
signal) are the enable bits.
If the BSR is the register selected by the current instruction
and the TAP controller is in the Capture-DR state, the
processor loads the BSR shift register as follows:
■
■
Chapter 11
If the current instruction is SAMPLE/PRELOAD, then the
current state of each input, output, and bidirectional pin is
loaded. A bidirectional pin is treated as an output if its
enable bit equals 1, and it is treated as an input if its enable
bit equals 0.
If the current instruction is EXTEST, then the current state
of each input pin is loaded. A bidirectional pin is treated as
an input, regardless of the state of its enable.
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While in the Shift-DR state, the BSR shift register is serially
shifted toward the TDO pin. During the shift, bit 280 of the
BSR is loaded from the TDI pin.
The BSR output register is loaded with the contents of the BSR
shift register in the Update-DR state. If the current instruction
is EXTEST, the processor’s output pins, as well as those
bidirectional pins that are enabled as outputs, are driven with
their corresponding values from the BSR output register.
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Table 38. Boundary Scan Bit Definitions
Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit
Pin/Enable
280 D35_E
247 D21
214 D4_E
181 A3
148 A20
115 A16
279 D35
246 D18_E
213 D4
180 A31_E
147 A13_E
114 FERR_E
278 D29_E
245 D18
212 DP0_E
179 A31
146 A13
113 FERR#
277 D29
244 D19_E
211 DP0
178 A21_E
145 DP7_E
112 HIT_E
276 D33_E
243 D19
210 HOLD
177 A21
144 DP7
111 HIT#
275 D33
242 D16_E
209 BOFF#
176 A30_E
143 BE6_E
110 BE7_E
274 D27_E
241 D16
208 AHOLD
175 A30
142 BE6#
109 BE7#
273 D27
240 D17_E
207 STPCLK#
174 A7_E
141 A12_E
108 NA#
272 DP3_E
239 D17
206 INIT
173 A7
140 A12
107 ADSC_E
271 DP3
238 D15_E
205 IGNNE#
172 A24_E
139 CLK
106 ADSC#
270 D25_E
237 D15
204 BF1
171 A24
138 BE4_E
105 BE5_E
269 D25
236 DP1_E
203 BF2
170 A18_E
137 BE4#
104 BE5#
268 D0_E
235 DP1
202 RESET
169 A18
136 A10_E
103 WB/WT#
267 D0
234 D13_E
201 BF0
168 A5_E
135 A10
102 PWT_E
266 D30_E
233 D13
200 FLUSH#
167 A5
134 D63_E
101 PWT
265 D30
232 D6_E
199 INTR
166 A22_E
133 D63
100 BE3_E
264 DP2_E
231 D6
198 NMI
165 A22
132 BE2_E
99
BE3#
263 DP2
230 D14_E
197 SMI#
164 EADS#
131 BE2#
98
BREQ_E
262 D2_E
229 D14
196 A25_E
163 A4_E
130 A15_E
97
BREQ
261 D2
228 D11_E
195 A25
162 A4
129 A15
96
PCD_E
260 D28_E
227 D11
194 A23_E
161 HITM_E
128 BRDY#
95
PCD
259 D28
226 D1_E
193 A23
160 HITM#
127 BE1_E
94
WR_E
258 D24_E
225 D1
192 A26_E
159 A9_E
126 BE1#
93
W/R#
257 D24
224 D12_E
191 A26
158 A9
125 A14_E
92
SMIACT_E
256 D26_E
223 D12
190 A29_E
157 SCYC_E
124 A14
91
SMIACT#
255 D26
222 D10_E
189 A29
156 SCYC
123 BRDYC#
90
EWBE#
254 D22_E
221 D10
188 A28_E
155 A8_E
122 BE0_E
89
DC_E
253 D22
220 D7_E
187 A28
154 A8
121 BE0#
88
D/C#
252 D23_E
219 D7
186 A27_E
153 A19_E
120 A17_E
87
APCHK_E
251 D23
218 D8_E
185 A27
152 A19
119 A17
86
APCHK#
250 D20_E
217 D8
184 A11_E
151 A6_E
118 KEN#
85
CACHE_E
249 D20
216 D9_E
183 A11
150 A6
117 A20M#
84
CACHE#
248 D21_E
215 D9
182 A3_E
149 A20_E
116 A16_E
83
ADS_E
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Table 38. Boundary Scan Bit Definitions (continued)
Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit Pin/Enable Bit
Pin/Enable
82
ADS#
68
DP6_E
54
D53_E
40
D43_E
26
D38_E
12
D3_E
81
AP_E
67
DP6
53
D53
39
D43
25
D38
11
D3
80
AP
66
D54_E
52
D47_E
38
D62_E
24
D58_E
10
D39_E
79
INV
65
D54
51
D47
37
D62
23
D58
9
D39
78
HLDA_E
64
D50_E
50
D59_E
36
D49_E
22
D42_E
8
D32_E
77
HLDA
63
D50
49
D59
35
D49
21
D42
7
D32
76
PCHK_E
62
D56_E
48
D51_E
34
DP4_E
20
D36_E
6
D5_E
75
PCHK#
61
D56
47
D51
33
DP4
19
D36
5
D5
74
LOCK_E
60
D55_E
46
D45_E
32
D46_E
18
D60_E
4
D37_E
73
LOCK#
59
D55
45
D45
31
D46
17
D60
3
D37
72
MIO_E
58
D48_E
44
D61_E
30
D41_E
16
D40_E
2
D31_E
71
M/IO#
57
D48
43
D61
29
D41
15
D40
1
D31
70
D52_E
56
D57_E
42
DP5_E
28
D44_E
14
D34_E
0
Reserved
69
D52
55
D57
41
DP5
27
D44
13
D34
Device Identification Register (DIR). The DIR is a 32-bit Test Data
Register selected during the execution of the IDCODE
instruction. The fields of the DIR and their values are shown in
Table 39 and are defined as follows:
■
■
■
■
Version Code—This 4-bit field is incremented by AMD
manufacturing for each major revision of silicon.
Part Number—This 16-bit field identifies the specific
processor model.
Manufacturer—This 11-bit field identifies the manufacturer
of the component (AMD).
LSB—The least significant bit (LSB) of the DIR is always set
to 1, as specified by the IEEE 1149.1 standard.
Table 39. Device Identification Register
210
Version Code
(Bits 31–28)
Part Number
(Bits 27–12)
Manufacturer
(Bits 11–1)
LSB
(Bit 0)
Xh
0560h
00000000001b
1b
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Bypass Register (BR). The BR is a Test Data Register consisting of
a 1-bit shift register that provides the shortest path between
TDI and TDO. When the processor is not involved in a test
operation, the BR can be selected by an instruction to allow the
transfer of test data through the processor without having to
serially scan the test data through the BSR. This functionality
preserves the state of the BSR and significantly reduces test
time.
The BR register is selected by the BYPASS and HIGHZ
instructions as well as by any instructions not supported by the
AMD-K6.
TAP Instructions
The processor supports the three instructions required by the
IEEE 1149.1 standard — EXTEST, SAMPLE/PRELOAD, and
BYPASS — as well as two additional optional instructions —
IDCODE and HIGHZ.
Table 40 shows the complete set of TAP instructions supported
by the processor along with the 5-bit Instruction Register
encoding and the register selected by each instruction.
Table 40. Supported Tap Instructions
Instruction
Encoding
Register
00000b
BSR
Sample inputs and drive outputs
SAMPLE / PRELOAD
00001b
BSR
Sample inputs and outputs, then load the BSR
IDCODE
00010b
DIR
Read DIR
HIGHZ
00011b
BR
Float outputs and bidirectional pins
BYPASS2
00100b–11110b
BR
Undefined instruction, execute the BYPASS instruction
BYPASS3
11111b
BR
Connect TDI to TDO to bypass the BSR
EXTEST
1
Description
Notes:
1. Following the execution of the EXTEST instruction, the processor must be reset in order to return to normal, non-test operation.
2. These instruction encodings are undefined on the AMD-K6 processor and default to the BYPASS instruction.
3. Because the TDI input contains an internal pullup, the BYPASS instruction is executed if the TDI input is not connected or open
during an instruction scan operation. The BYPASS instruction does not affect the normal operational state of the processor.
EXTEST. When the EXTEST instruction is execut ed, the
processor loads the BSR shift register with the current state of
the input and bidirectional pins in the Capture-DR state and
drives the output and bidirectional pins with the corresponding
values from the BSR output register in the Update-DR state.
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SAMPLE/PRELOAD. The SAMPLE/PRELOAD instruction performs
two functions. These functions are as follows:
■
■
During the Capture-DR state, the processor loads the BSR
shift register with the current state of every input, output,
and bidirectional pin.
During the Update-DR state, the BSR output register is
loaded from the BSR shift register in preparation for the
next EXTEST instruction.
The SAMPLE/PRELOAD instruction does not affect the normal
operational state of the processor.
BYPASS. The BYPASS instruction selects the BR register, which
reduces the boundary-scan length through the processor from
281 to one (TDI to BR to TDO). The BYPASS instruction does
not affect the normal operational state of the processor.
IDCODE. The IDCODE instruction selects the DIR register,
allowing the device identification code to be shifted out of the
processor. This instruction is loaded into the IR when the TAP
controller is reset. The IDCODE instruction does not affect the
normal operational state of the processor.
HIGHZ. T h e H I G H Z i n s t r u c t i o n f o rc e s a l l o u t p u t a n d
bidirectional pins to be floated. During this instruction, the BR
is selected and the normal operational state of the processor is
not affected.
TAP Controller State
Machine
212
The TAP controller state diagram is shown in Figure 73 on page
213. State transitions occur on the rising edge of TCK. The
logic 0 or 1 next to the states represents the value of the TMS
signal sampled by the processor on the rising edge of TCK.
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Test-Logic-Reset
1
0
Run-Test/Idle
1
1
Select-DR-Scan
1
Select-IR-Scan
0
0
0
1
Capture-DR
1
Capture-IR
0
0
Shift-DR
Shift-IR
0
0
1
1
1
Exit1-DR
Exit1-IR
0
0
Pause-DR
1
Pause-IR
0
0
1
1
Exit2-IR
Exit2-DR
0
0
1
1
Update-IR
Update-DR
0
1
1
0
IEEE Std 1149.1-1990, Copyright © 1990. IEEE. All rights reserved
Figure 73. TAP State Diagram
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The states of the TAP controller are described as follows:
Test-Logic-Reset. This state represents the initial reset state of the
TAP controller and is entered when the processor samples
RESET asserted, when TRST# is asynchronously asserted, and
when TMS is sampled High for five or more consecutive clocks.
In addition, this state can be entered from the Select-IR-Scan
state. The IR is initialized with the IDCODE instruction, and
the processor’s normal operation is not affected in this state.
Capture-DR. During the SAMPLE/PRELOAD instruction, the
processor loads the BSR shift register with the current state of
every input, output, and bidirectional pin. During the EXTEST
instruction, the processor loads the BSR shift register with the
current state of every input and bidirectional pin.
Capture-IR. When the TAP controller enters the Capture-IR
state, the processor loads 01b into the two least significant bits
of the IR shift register and loads 000b into the three most
significant bits of the IR shift register.
Shift-DR. While in the Shift-DR state, the selected TDR shift
register is serially shifted toward the TDO pin. During the
shift, the most significant bit of the TDR is loaded from the
TDI pin.
Shift-IR. While in the Shift-IR state, the IR shift register is
serially shifted toward the TDO pin. During the shift, the most
significant bit of the IR is loaded from the TDI pin.
Update-DR. During the SAMPLE/PRELOAD instruction, the BSR
output register is loaded with the contents of the BSR shift
register. During the EXTEST instruction, the output pins, as
well as those bidirectional pins defined as outputs, are driven
with their corresponding values from the BSR output register.
Update-IR. In this state, the IR output register is loaded from the
IR shift register, and the current instruction is defined by the
IR output register.
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The following states have no effect on the normal or test
operation of the processor other than as shown in Figure 73 on
page 213:
■
■
■
■
■
■
■
■
■
11.4
Purpose
Run-Test/Idle—This state is an idle state between scan
operations.
Select-DR-Scan—This is the initial state of the test data
register state transitions.
Select-IR-Scan—This is the initial state of the Instruction
Register state transitions.
Exit1-DR—This state is entered to terminate the shifting
process and enter the Update-DR state.
Exit1-IR—This state is entered to terminate the shifting
process and enter the Update-IR state.
Pause-DR—This state is entered to temporarily stop the
shifting process of a Test Data Register.
Pause-IR—This state is entered to temporarily stop the
shifting process of the Instruction Register.
Exit2-DR—This state is entered in order to either terminate
the shifting process and enter the Update-DR state or to
resume shifting following the exit from the Pause-DR state.
Exit2-IR—This state is entered in order to either terminate
the shifting process and enter the Update-IR state or to
resume shifting following the exit from the Pause-IR state.
L1 Cache Inhibit
The AMD-K6 processor provides a means for inhibiting the
normal operation of its L1 instruction and data caches while
still supporting an external Level-2 (L2) cache. This capability
allows system designers to disable the L1 cache during the
testing and debug of an L2 cache.
If the Cache Inhibit bit (bit 3) of Test Register 12 (TR12) is set
to 0, the processor’s L1 cache is enabled and operates as
described in “Cache Organization” on page 171. If the Cache
Inhibit bit is set to 1, the L1 cache is disabled and no new cache
lines are allocated. Even though new allocations do not occur,
valid L1 cache lines remain valid and are read by the processor
when a requested address hits a cache line. In addition, the
processor continues to support inquire cycles initiated by the
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system logic, including the execution of writeback cycles when
a modified cache line is hit.
While the L1 is inhibited, the processor continues to drive the
PCD output signal appropriately, which system logic can use to
control external L2 caching.
In order to completely disable the L1 cache so no valid lines
exist in the cache, the Cache Inhibit bit must be set to 1 and
the cache must be flushed in one of the following ways:
■
■
■
11.5
By asserting the FLUSH# input signal
By executing the WBINVD instruction
By executing the INVD instruction (modified cache lines are
not written back to memory)
Debug
The AMD-K6 processor implements the standard x86 debug
functions, registers, and exceptions. In addition, the processor
supports the I/O breakpoint debug extension. The debug
feature assists programmers and system designers during
software execution tracing by generating exceptions when one
or more events occur during processor execution. The
exception handler, or debugger, can be written to perform
various tasks, such as displaying the conditions that caused the
breakpoint to occur, displaying and modifying register or
memory contents, or single-stepping through program
execution.
The following sections describe the debug registers and the
various types of breakpoints and exceptions that the processor
supports.
Debug Registers
216
Figures 74 through 77 show the 32-bit debug registers
supported by the processor.
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Symbol
LEN 3
R/W 3
LEN 2
R/W 2
LEN 1
R/W 1
LEN 0
R/W 0
Description
Length of Breakpoint #3
Type of Transaction(s) to Trap
Length of Breakpoint #2
Type of Transaction(s) to Trap
Length of Breakpoint #1
Type of Transaction(s) to Trap
Length of Breakpoint #0
Type of Transaction(s) to Trap
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
LEN
3
R/W
3
LEN
2
R/W
2
LEN
1
R/W
1
LEN
0
R/W
0
G
D
G
E
8
7
Bits
31–30
29–28
27–26
25–24
23–22
21–20
19–18
17–16
6
5
4
3
L G L
E 3 3
L
2
L G
2 1
2
1
0
L G
1 0
L
0
Reserved
Symbol
GD
GE
LE
G3
L3
G2
L2
G1
L1
G0
L0
Description
General Detect Enabled
Global Exact Breakpoint Enabled
Local Exact Breakpoint Enabled
Global Exact Breakpoint # 3 Enabled
Local Exact Breakpoint # 3 Enabled
Global Exact Breakpoint # 2 Enabled
Local Exact Breakpoint # 2 Enabled
Global Exact Breakpoint # 1 Enabled
Local Exact Breakpoint # 1 Enabled
Global Exact Breakpoint # 0 Enabled
Local Exact Breakpoint # 0 Enabled
Bit
13
9
8
7
6
5
4
3
2
1
0
Figure 74. Debug Register DR7
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31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
B B B
T S D
3
2
1
0
B
3
B
2
B
1
B
0
Reserved
Symbol
BT
BS
BD
B3
B2
B1
B0
Description
Breakpoint Task Switch
Breakpoint Single Step
Breakpoint Debug Access Detected
Breakpoint #3 Condition Detected
Breakpoint #2 Condition Detected
Breakpoint #1 Condition Detected
Breakpoint #0 Condition Detected
Bit
15
14
13
3
2
1
0
Figure 75. Debug Register DR6
DR5
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
Reserved
DR4
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Reserved
Figure 76. Debug Registers DR5 and DR4
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DR3
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
8
7
6
4
3
2
1
0
8
7
6
4
3
2
1
0
Breakpoint 3 32-bit Linear Address
DR2
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Breakpoint 2 32-bit Linear Address
DR1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
5
Breakpoint 1 32-bit Linear Address
DR0
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
5
Breakpoint 0 32-bit Linear Address
Figure 77. Debug Registers DR3, DR2, DR1, and DR0
DR3–DR0. The processor allows the setting of up to four
breakpoints. DR3–DR0 contain the linear addresses for
breakpoint 3 through breakpoint 0, respectively, and are
compared to the linear addresses of processor cycles to
determine if a breakpoint occurs. Debug register DR7 defines
the specific type of cycle that must occur in order for the
breakpoint to occur.
DR5–DR4. When debugging extensions are disabled (bit 3 of
CR4 is set to 0), the DR5 and DR4 registers are mapped to DR7
and DR6, respectively, in order to be software compatible with
previous generations of x86 processors. When debugging
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extensions are enabled (bit 3 of CR4 is set to 1), any attempt to
load DR5 or DR4 results in an undefined opcode exception.
Likewise, any attempt to store DR5 or DR4 also results in an
undefined opcode exception.
DR6. If a breakpoint is enabled in DR7, and the breakpoint
conditions as defined in DR7 occur, then the corresponding
B-bit (B3–B0) in DR6 is set to 1. In addition, any other
breakpoints defined using these particular breakpoint
conditions are reported by the processor by setting the
appropriate B-bits in DR6, regardless of whether these
breakpoints are enabled or disabled. However, if a breakpoint
is not enabled, a debug exception does not occur for that
breakpoint.
If the processor decodes an instruction that writes or reads
DR7 through DR0, the BD bit (bit 13) in DR6 is set to 1 (if
enabled in DR7) and the processor generates a debug
exception. This operation allows control to pass to the
debugger prior to debug register access by software.
If the Trap Flag (bit 8) of the EFLAGS register is set to 1, the
processor generates a debug exception after the successful
execution of every instruction (single-step operation) and sets
the BS bit (bit 14) in DR6 to indicate the source of the
exception.
When the processor switches to a new task and the debug trap
bit (T-bit) in the corresponding Task State Segment (TSS) is set
to 1, the processor sets the BT bit (bit 15) in DR6 and generates
a debug exception.
DR7. When set to 1, L3–L0 locally enable breakpoints 3 through
0, respectively. L3–L0 are set to 0 whenever the processor
executes a task switch. Setting L3–L0 to 0 disables the
breakpoints and ens ures that these particular debug
exceptions are only generated for a specific task.
When set to 1, G3–G0 globally enable breakpoints 3 through 0,
respectively. Unlike L3–L0, G3–G0 are not set to 0 whenever
the processor executes a task switch. Not setting G3–G0 to 0
allows breakpoints to remain enabled across all tasks. If a
breakpoint is enabled globally but disabled locally, the global
enable overrides the local enable.
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The LE (bit 8) and GE (bit 9) bits in DR7 have no effect on the
operation of the processor and are provided in order to be
software compatible with previous generations of x86
processors.
When set to 1, the GD bit in DR7 (bit 13) enables the debug
exception associated with the BD bit (bit 13) in DR6. This bit is
set to 0 when a debug exception is generated.
LEN3–LEN0 and RW3–RW0 are two-bit fields in DR7 that
specify the length and type of each breakpoint as defined in
Table 41.
Table 41. DR7 LEN and RW Definitions
LEN Bits1
RW Bits
Breakpoint
00b
00b2
Instruction Execution
00b
One-byte Data Write
01b
01b
Two-byte Data Write
11b
Four-byte Data Write
00b
One-byte I/O Read or Write
10b3
01b
Two-byte I/O Read or Write
11b
Four-byte I/O Read or Write
00b
One-byte Data Read or Write
01b
11b
11b
Two-byte Data Read or Write
Four-byte Data Read or Write
Notes:
1. LEN bits equal to 10b is undefined.
2. When RW equals 00b, LEN must be equal to 00b.
3. When RW equals 10b, debugging extensions (DE) must be enabled (bit 3 of CR4 must be set
to 1). If DE is set to 0, then RW equal to 10b is undefined.
Debug Exceptions
Chapter 11
A debug exception is categorized as either a debug trap or a
debug fault. A debug trap calls the debugger following the
execution of the instruction that caused the trap. A debug fault
calls the debugger prior to the execution of the instruction that
caused the fault. All debug traps and faults generate either an
Interrupt 01h or an Interrupt 03h exception.
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Interrupt 01h. The following events are considered debug traps
that cause the processor to generate an Interrupt 01h
exception:
■
■
■
Enabled breakpoints for data and I/O cycles
Single Step Trap
Task Switch Trap
The following events are considered debug faults that cause
the processor to generate an Interrupt 01h exception:
■
■
Enabled breakpoints for instruction execution
BD bit in DR6 set to 1
Interrupt 03h. The INT 3 instruction is defined in the x86
architecture as a breakpoint instruction. This instruction
causes the processor to generate an Interrupt 03h exception.
This exception is a debug trap because the debugger is called
following the execution of the INT 3 instruction.
The INT 3 instruction is a one-byte instruction (opcode CCh)
typically used to insert a breakpoint in software by writing
CCh to the address of the first byte of the instruction to be
trapped (the target instruction). Following the trap, if the
target instruction is to be executed, the debugger must replace
the INT 3 instruction with the first byte of the target
instruction.
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12
Clock Control
The AMD-K6 processor supports five modes of clock control.
The processor can transition between these modes to maximize
performance, to minimize power dissipation, or to provide a
balance between performance and power. (See “Power
Dissipation” on page 235 for the maximum power dissipation of
the AMD-K6 processor within the normal and reduced-power
states.)
The five clock-control states supported are as follows:
■
■
■
■
■
Normal State: The processor is running in Real Mode,
Virtual-8086 Mode, Protected Mode, or System Management
Mode (SMM). In this state, all clocks are running—including
the external bus clock CLK and the internal processor
clock—and the full features and functions of the processor
are available.
Halt State: This low-power state is entered following the
successful execution of the HLT instruction. During this
state, the internal processor clock is stopped.
Stop Grant State: This low-power state is entered following
the recognition of the assertion of the STPCLK# signal.
During this state, the internal processor clock is stopped.
Stop Grant Inquire State: This state is entered from the Halt
state and the Stop Grant state as the result of a
system-initiated inquire cycle.
Stop Clock State: This low-power state is entered from the
Stop Grant state when the CLK signal is stopped.
The following sections describe each of the four low-power
states. Figure 78 on page 228 illustrates the clock control state
transitions.
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Halt State
Enter Halt State
During the execution of the HLT instruction, the AMD-K6
processor executes a Halt special cycle. After BRDY# is
sampled asserted during this cycle, and then EWBE# is also
sampled asserted, the processor enters the Halt state in which
the processor disables most of its internal clock distribution. In
order to support the following operations, the internal
phase-lock loop (PLL) still runs, and some internal resources
are still clocked in the Halt state:
■
■
■
■
Inquire Cycles: The processor continues to sample AHOLD,
BOFF#, and HOLD in order to support inquire cycles that
are initiated by the system logic. The processor transitions to
the Stop Grant Inquire state during the inquire cycle. After
returning to the Halt state following the inquire cycle, the
processor does not execute another Halt special cycle.
Flush Cycles: The processor continues to sample FLUSH#. If
FLUSH# is sampled asserted, the processor performs the
flush operation in the same manner as it is performed in the
Normal state. Upon completing the flush operation, the
processor executes the Halt special cycle which indicates
the processor is in the Halt state.
Time Stamp Counter (TSC): The TSC continues to count in
the Halt state.
Signal Sampling: The processor continues to sample INIT,
INTR, NMI, RESET, and SMI#.
After entering the Halt state, all signals driven by the processor
retain their state as they existed following the completion of
the Halt special cycle.
Exit Halt State
224
The AMD-K6 processor remains in the Halt state until it
samples INIT, INTR (if interrupts are enabled), NMI, RESET, or
SMI# asserted. If any of these signals is sampled asserted, the
processor returns to the Normal state and performs the
corresponding operation. All of the normal requirements for
recognition of these input signals apply within the Halt state.
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12.2
Stop Grant State
Enter Stop Grant
State
After recognizing the assertion of STPCLK#, the AMD-K6
processor flushes its instruction pipelines, completes all
pending and in-progress bus cycles, and acknowledges the
STPCLK# assertion by executing a Stop Grant special bus cycle.
After BRDY# is sampled asserted during this cycle, and then
EWBE# is also sampled asserted, the processor enters the Stop
Grant state. The Stop Grant state is like the Halt state in that
the processor disables most of its internal clock distribution in
the Stop Grant state. In order to support the following
operations, the internal PLL still runs, and some internal
resources are still clocked in the Stop Grant state:
■
■
■
Inquire cycles: The processor transitions to the Stop Grant
Inquire state during an inquire cycle. After returning to the
Stop Grant state following the inquire cycle, the processor
does not execute another Stop Grant special cycle.
Time Stamp Counter (TSC): The TSC continues to count in
the Stop Grant state.
Signal Sampling: The processor continues to sample INIT,
INTR, NMI, RESET, and SMI#.
FLUSH# is not recognized in the Stop Grant state (unlike while
in the Halt state).
Upon entering the Stop Grant state, all signals driven by the
processor retain their state as they existed following the
completion of the Stop Grant special cycle.
Exit Stop Grant State
The AMD-K6 processor remains in the Stop Grant state until it
samples STPCLK# negated or RESET asserted. If STPCLK# is
sampled negated, the processor returns to the Normal state in
less than 10 bus clock (CLK) periods. After the transition to the
Norm al state, the processor resumes execution at the
instruction boundary on which STPCLK# was initially
recognized.
If STPCLK# is recognized as negated in the Stop Grant state
and subsequently sampled asserted prior to returning to the
Normal state, the AMD-K6 processor guarantees that a
minimum of one instruction is executed prior to re-entering the
Stop Grant state.
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If INIT, INTR (if interrupts are enabled), FLUSH#, NMI, or
SMI# are sampled asserted in the Stop Grant state, the
processor latches the edge-sensitive signals (INIT, FLUSH#,
NMI, and SMI#), but otherwise does not exit the Stop Grant
state to service the interrupt. When the processor returns to the
Normal state due to sampling STPCLK# negated, any pending
interrupts are recognized after returning to the Normal state.
To ensure their recognition, all of the normal requirements for
these input signals apply within the Stop Grant state.
If RESET is sampled asserted in the Stop Grant state, the
processor immediately returns to the Normal state and the
reset process begins.
12.3
Stop Grant Inquire State
Enter Stop Grant
Inquire State
The Stop Grant Inquire state is entered from the Stop Grant
state or the Halt state when EADS# is sampled asserted during
an inquire cycle initiated by the system logic. The AMD-K6
processor responds to an inquire cycle in the same manner as in
the Normal state by driving HIT# and HITM#. If the inquire
cycle hits a modified data cache line, the processor performs a
writeback cycle.
Exit Stop Grant
Inquire State
Following the completion of any writeback, the processor
returns to the state from which it entered the Stop Grant
Inquire state.
12.4
Stop Clock State
Enter Stop Clock
State
If the CLK signal is stopped while the AMD-K6 processor is in
the Stop Grant state, the processor enters the Stop Clock state.
Because all internal clocks and the PLL are not running in the
Stop Clock s tat e, the St op Clock st at e represe nt s t he
minimum-power state of all clock control states. The CLK signal
must be held Low while it is stopped.
The Stop Clock state cannot be entered from the Halt state.
INTR is the only input signal that is allowed to change states
while the processor is in the Stop Clock state. However, INTR is
not sampled until the processor returns to the Stop Grant state.
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All other input signals must remain unchanged in the Stop
Clock state.
Exit Stop Clock State
The AMD-K6 processor returns to the Stop Grant state from the
Stop Clock state after the CLK signal is started and the internal
PLL has stabilized. PLL stabilization is achieved after the CLK
signal has been running within its specification for a minimum
of 1.0 ms.
The frequency of CLK when exiting the Stop Clock state can be
different than the frequency of CLK when entering the Stop
Clock state.
The state of the BF[2:0] signals when exiting the Stop Clock
state is ignored because the BF[2:0] signals are only sampled
during the falling transition of RESET.
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HLT Instruction
RESET, SMI#, INIT,
or INTR Asserted
Halt
State
EADS# Asserted
Writeback
Completed
Normal Mode
- Real
- Virtual-8086
- Protected
- SMM
Stop Grant
Inquire
State
STPCLK# Asserted
STPCLK# Negated,
or RESET Asserted
EADS# Asserted
Stop Grant
State
Writeback
Completed
CLK
Started
CLK
Stopped
Stop Clock
State
Figure 78. Clock Control State Transitions
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13
13.1
Power and Grounding
Power Connections
The AMD-K6 processor is a dual voltage device. Two separate
supply voltages are required: VCC2 and VCC3. VCC2 provides the
core voltage for the processor and VCC3 provides the I/O voltage.
See “Electrical Data” on page 233 for the value and range of VCC2
and VCC3.
There are 28 V CC2 , 32 V CC3 , and 68 V SS pins on the AMD-K6
processor. (See “Pin Designations” on page 269 for all power
and ground pin designations.) The large number of power and
ground pins are provided to ensure that the processor and
package maintain a clean and stable power distribution
network.
For proper operation and functionality, all VCC2, VCC3, and VSS
pins must be connected to the appropriate planes in the circuit
board. The power planes have been arranged in a pattern to
simplify routing and minimize crosstalk on the circuit board.
The isolation region between two voltage planes must be at
least 0.254mm if they are in the same layer of the circuit board.
( S e e Fi g u re 7 9 o n p a g e 2 3 0 . ) I n o rd e r t o m a i n t a i n a
low-impedance current sink and reference, the ground plane
must never be split.
Although the AMD-K6 has two separate supply voltages, there
are no special power sequencing requirements. The best
procedure is to minimize the time between which VCC2 and VCC3
are either both on or both off.
Chapter 13
Power and Grounding
229
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
C21
C2
C11
CC4
+
+
CC5
CC6
C12
C13
VCC3 (I/O) Plane
C26
CC10
C22
C23
C24
CC8
C1
+
+
+
C25
C29
C27
C30
C28
C31
CC7
CC3
C15
C7
C9
C20
C16
C6
C10
C17
C19
C18
C5
CC9
C8
C14
0.254mm (min.) for
isolation region
VCC2 (Core) Plane
CC1
CC2
Figure 79. Suggested Component Placement
13.2
Decoupling Recommendations
In addition to the isolation region mentioned in “Power
Connections” on page 229, adequate decoupling capacitance is
required between the two system power planes and the ground
plane to minimize ringing and to provide a low-impedance path
for return currents. Suggested decoupling capacitor placement
is shown in Figure 79.
Surface mounted capacitors should be used under the
processor’s ZIF socket to minimize resistance and inductance in
the lead lengths while maintaining minimal height. For
information and recommendations about the specific value,
quantity, and location of the capacitors, see the AMD-K6 ®
Processor Power Supply Design Application Note, order# 21103.
230
Power and Grounding
Chapter 13
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
13.3
Pin Connection Requirements
For proper operation, the following requirements for signal pin
connections must be met:
■
■
■
■
■
Chapter 13
Do not drive address and data signals into large capacitive
loads at high frequencies. If necessary, use buffer chips to
drive large capacitive loads.
Leave all NC (no-connect) pins unconnected.
Unused inputs should always be connected to an
appropriate signal level.
• Active Low inputs that are not being used should be
connected to VCC3 through a 20k-Ω pullup resistor.
• Active High inputs that are not being used should be
connected to GND through a pulldown resistor.
Reserved signals can be treated in one of the following ways:
• As no-connect (NC) pins, in which case these pins are left
unconnected
• As pins connected to the system logic as defined by the
industry-standard Pentium interface (Socket 7)
• Any combination of NC and Socket 7 pins
Keep trace lengths to a minimum.
Power and Grounding
231
Preliminary Information
AMD-K6® Processor Data Sheet
232
20695H/0—March 1998
Power and Grounding
Chapter 13
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
14
14.1
Electrical Data
Operating Ranges
The func tional operation of the AMD-K6 proce ssor is
guaranteed if the voltage and temperature parameters are
within the limits defined in Table 42.
Table 42. Operating Ranges
Parameter
Minimum
Typical
Maximum
Comments
2.755 V
2.9 V
3.045 V
Note 1, 2
3.1 V
3.2 V
3.3 V
Note 1, 3
VCC3
3.135 V
3.3 V
3.6 V
Note 1
TCASE
0°C
VCC2
70°C
Notes:
1. VCC2 and VCC3 are referenced from VSS.
2. VCC2 specification for 2.9 V components.
3. VCC2 specification for 3.2 V components.
14.2
Absolute Ratings
While functional operation is not guaranteed beyond the
operating ranges listed in Table 42, no long-term reliability or
functional damage is caused as long as the AMD-K6 processor is
not subjected to conditions exceeding the absolute ratings
listed in Table 43.
Table 43. Absolute Ratings
Parameter
Minimum
Maximum
VCC2
–0.5 V
3.5 V
VCC3
–0.5 V
4.0 V
VPIN
–0.5 V
TCASE (under bias)
–65°C
+110°C
TSTORAGE
–65°C
+150°C
VCC3+0.5 V and
≤ 4.0 V
Comments
Note
Note:
VPIN (the voltage on any I/O pin) must not be greater than 0.5 V above the voltage being applied
to VCC3. In addition, the VPIN voltage must never exceed 4.0 V.
Chapter 14
Electrical Data
233
Preliminary Information
AMD-K6® Processor Data Sheet
14.3
20695H/0—March 1998
DC Characteristics
The DC characteristics of the AMD-K6 processor are shown in
Table 44.
Table 44. DC Characteristics
Symbol
Parameter Description
VIL
Preliminary Data
Comments
Min
Max
Input Low Voltage
– 0.3 V
+0.8 V
VIH
Input High Voltage
2.0 V
VCC3 +0.3 V
Note 1
VOL
Output Low Voltage
0.4 V
IOL = 4.0-mA load
VOH
Output High Voltage
ICC2
2.9 V Power Supply Current
ICC2
3.2 V Power Supply Current
ICC3
IOH = 3.0-mA load
2.4 V
3.3 V Power Supply Current
6.25 A
166 MHz, Note 2
7.50 A
200 MHz, Note 2
9.50 A
233 MHz, Note 3
0.48 A
166 MHz, Note 4
0.50 A
200 MHz, Note 4
0.52 A
233 MHz, Note 4
ILI
Input Leakage Current
±15 µA
Note 5
ILO
Output Leakage Current
±15 µA
Note 5
IIL
Input Leakage Current Bias with Pullup
–400 µA
Note 6
IIH
Input Leakage Current Bias with Pulldown
200 µA
Note 7
CIN
Input Capacitance
15 pF
COUT
Output Capacitance
20 pF
COUT
I/O Capacitance
25 pF
CCLK
CLK Capacitance
15 pF
CTIN
Test Input Capacitance (TDI, TMS, TRST#)
15 pF
CTOUT
Test Output Capacitance (TDO)
20 pF
CTCK
TCK Capacitance
15 pF
Notes:
1.
2.
3.
4.
5.
6.
7.
234
VCC3 refers to the voltage being applied to VCC3 during functional operation.
VCC2 = 3.045 V — The maximum power supply current must be taken into account when designing a power supply.
VCC2 = 3.3 V — The maximum power supply current must be taken into account when designing a power supply.
VCC3 = 3.6 V — The maximum power supply current must be taken into account when designing a power supply.
Refers to inputs and I/O without an internal pullup resistor and 0 ≤ VIN ≤ VCC3.
Refers to inputs with an internal pullup and VIL = 0.4V.
Refers to inputs with an internal pulldown and VIH = 2.4V.
Electrical Data
Chapter 14
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
14.4
Power Dissipation
Table 45 contains the typical and maximum power dissipation
of the AMD-K6 processor during normal and reduced power
states.
Table 45. Typical and Maximum Power Dissipation
Clock Control State
2.9 V Component
3.2 V Component
Comments
166 MHz
200 MHz
233 MHz
Normal (Maximum Thermal Power)
17.2 W
20.0 W
28.3 W
Note 1, 2
Normal (Typical Thermal Power)
10.3 W
12.0 W
17.0 W
Note 3
Stop Grant / Halt (Maximum)
1.45 W
1.53 W
1.75 W
Note 4
Stop Clock (Maximum)
1.0 W
1.0 W
1.0 W
Note 5
Notes:
1. The maximum power dissipated in the normal clock control state must be taken into account when designing a
solution for thermal dissipation for the AMD-K6 processor.
2. Maximum power is determined for the worst-case instruction sequence or function for the listed clock control states
with VCC2 = 2.9 V (for the 2.9 V component) or VCC2 = 3.2 V (for the 3.2 V component), and VCC3 = 3.3 V.
3. Typical power is determined for the typical instruction sequences or functions associated with normal system
operation with VCC2 = 2.9 V (for the 2.9 V component) or VCC2 = 3.2 V (for the 3.2 V component), and VCC3 = 3.3 V.
4. The CLK signal and the internal PLL are still running but most internal clocking has stopped.
5. The CLK signal, the internal PLL, and all internal clocking has stopped.
Chapter 14
Electrical Data
235
Preliminary Information
AMD-K6® Processor Data Sheet
236
20695H/0—March 1998
Electrical Data
Chapter 14
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
15
I/O Buffer Characteristics
All of the AMD-K6 processor inputs, outputs, and bidirectional
buffers are implemented using a 3.3 V buffer design. In
addition, a subset of the processor I/O buffers include a second,
higher drive strength option. These buffers can be configured to
provide the higher drive strength for applications that place a
heavier load on these I/O signals.
AMD has developed two I/O buffer models that represent the
characteristics of each of the two possible drive strength
configurations supported by the AMD-K6. These two models are
called the Standard I/O Model and the Strong I/O Model.
AMD developed the two models to allow system designers to
perform analog simulations of AMD-K6 signals that interface
with the system logic. Analog simulations are used to determine
a signal’s time of flight from source to destination and to ensure
that the system’s signal quality requirements are met. Signal
quality measurements include overshoot, undershoot, slope
reversal, and ringing.
15.1
Selectable Drive Strength
The AMD-K6 processor samples the BRDYC# input during the
falling transition of RESET to configure the drive strength of
A[20:3], ADS#, HITM# and W/R#. If BRDYC# is 0 during the fall
of RESET, these particular outputs are configured using the
higher drive strength. If BRDYC# is 1 during the fall of RESET,
the standard drive strength is selected for all I/O buffers.
Table 46 shows the relationship between BRDYC# and the two
available drive strengths — K6STD and K6STG.
Table 46. A[20:3], ADS#, HITM#, and W/R# Strength Selection
Chapter 15
Drive Strength
BRDYC#
I/O Buffer Name
Strength 1 (standard)
1
K6STD
Strength 2 (strong)
0
K6STG
I/O Buffer Characteristics
237
Preliminary Information
AMD-K6® Processor Data Sheet
15.2
20695H/0—March 1998
I/O Buffer Model
AMD provides models of the AMD-K6 processor I/O buffers for
system designers to use in board-level simulations. These I/O
b u f f e r m o d e l s co n fo r m t o t h e I / O B u f f e r I n f o r m a t i o n
Specification (IBIS), Version 2.1. The Standard I/O Model uses
K6STD, the standard I/O buffer representation, for all I/O
buffers. The Strong I/O Model uses K6STG, the stronger I/O
buffer representation for A[20:3], ADS#, HITM#, and W/R#,
and uses K6STD for the remainder of the I/O buffers.
Both I/O models contain voltage versus current (V/I) and
voltage versus time (V/T) data tables for accurate modeling of
I/O buffer behavior.
The following list characterizes the properties of each I/O
buffer model:
■
■
■
■
■
■
■
■
238
All data tables contain minimum, typical, and maximum
values to allow for worst-case, typical, and best-case
simulations, respectively.
The pullup, pulldown, power clamp, and ground clamp
device V/I tables contain enough data points to accurately
represent the nonlinear nature of the V/I curves. In addition,
the voltage ranges provided in these tables extend beyond
the normal operating range of the AMD-K6 processor for
those simulators that yield more accurate results based on
this wider range. Figure 80 and Figure 81 on page 239
illustrate the min/typ/max pulldown and pullup V/I curves
for K6STD between 0V and 3.3V.
The rising and falling ramp rates are specified.
The min/typ/max VCC3 operating range is specified as
3.135V, 3.3V, and 3.6V, respectively.
Vil = 0.8V, Vih = 2.0V, and Vmeas = 1.5V
The R/L/C of the package is modeled.
The capacitance of the silicon die is modeled.
The model assumes the test load is 0 capacitance, resistance,
inductance, and voltage.
I/O Buffer Characteristics
Chapter 15
Preliminary Information
AMD-K6® Processor Data Sheet
3.3
3.0
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0
70
60
50
40
30
20
10
0
0.3
Iol (mA)
20695H/0—March 1998
Voutput (V)
Ioh (mA)
3.3
3.0
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0.3
0
Figure 80. K6STD Pulldown V/I Curves
0
-10
-20
-30
-40
-50
-60
-70
Voutput (V)
Figure 81. K6STD Pullup V/I Curves
15.3
I/O Model Application Note
For the AMD-K6 processor I/O Buffer IBIS Models and their
application, refer to the AMD-K6® Processor I/O Model (IBIS)
Application Note, order# 21084.
15.4
I/O Buffer AC and DC Characteristics
See “Signal Switching Characteristics” on page 241 for the
AMD-K6 processor AC timing specifications.
See “Electrical Data” on page 233 for the AMD-K6 processor
DC specifications.
Chapter 15
I/O Buffer Characteristics
239
Preliminary Information
AMD-K6® Processor Data Sheet
240
20695H/0—March 1998
I/O Buffer Characteristics
Chapter 15
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
16
Signal Switching Characteristics
The AMD-K6 processor signal switching characteristics are
presented in Table 47 through Table 55. Valid delay, float,
setup, and hold timing specifications are listed. These
specifications are provided for the system designer to
determine if the timings necessary for the processor to
interface with the system logic are met. Table 47 and Table 48
contain the switching characteristics of the CLK input. Table
49 through Table 52 contain the timings for the normal
operation signals. Table 53 contains the timings for RESET and
the configuration signals. Table 54 and Table 55 contain the
timings for the test operation signals.
All signal timings provided are:
■
■
■
■
16.1
Measured between CLK, TCK, or RESET at 1.5 V and the
corresponding signal at 1.5 V—this applies to input and output signals that are switching from Low to High, or from
High to Low
Based on input signals applied at a slew rate of 1 V/ns
between 0 V and 3 V (rising) and 3 V to 0 V (falling)
Valid within the operating ranges given in “Operating
Ranges” on page 233
Based on a load capacitance (CL) of 0 pF
CLK Switching Characteristics
Table 47 and Table 48 contain the switching characteristics of
the CLK input to the AMD-K6 processor for 66-MHz and
60-MHz bus operation, respectively, as measured at the voltage
levels indicated by Figure 82.
The CLK Period Stability specifies the variance (jitter) allowed
between successive periods of the CLK input measured at 1.5
V. This parameter must be considered as one of the elements of
clock skew between the AMD-K6 and the system logic.
Chapter 16
Signal Switching Characteristics
241
Preliminary Information
AMD-K6® Processor Data Sheet
16.2
20695H/0—March 1998
Clock Switching Characteristics for 66-MHz Bus Operation
Table 47. CLK Switching Characteristics for 66-MHz Bus Operation
Symbol
Parameter Description
Preliminary Data
Figure
Min
Max
Frequency
33.3 MHz
66.6 MHz
t1
CLK Period
15.0 ns
30.0 ns
t2
CLK High Time
4.0 ns
82
t3
CLK Low Time
4.0 ns
82
t4
CLK Fall Time
0.15 ns
1.5 ns
82
t5
CLK Rise Time
0.15 ns
1.5 ns
82
In Normal Mode
82
± 250 ps
CLK Period Stability
Comments
In Normal Mode
Note
Note:
Jitter frequency power spectrum peaking must occur at frequencies greater than (Frequency of CLK)/3 or less than 500 KHz.
16.3
Clock Switching Characteristics for 60-MHz Bus Operation
Table 48. CLK Switching Characteristics for 60-MHz Bus Operation
Symbol
Parameter Description
Preliminary Data
Figure
Min
Max
Frequency
30 MHz
60 MHz
t1
CLK Period
16.67 ns
33.33 ns
t2
CLK High Time
4.0 ns
82
t3
CLK Low Time
4.0 ns
82
t4
CLK Fall Time
0.15 ns
1.5 ns
82
t5
CLK Rise Time
0.15 ns
1.5 ns
82
CLK Period Stability
± 250 ps
Comments
In Normal Mode
82
In Normal Mode
Note
Note:
Jitter frequency power spectrum peaking must occur at frequencies greater than (Frequency of CLK)/3 or less than 500 KHz.
242
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
t2
2.0 V
1.5 V
t3
0.8 V
t4
t5
t1
Figure 82. CLK Waveform
16.4
Valid Delay, Float, Setup, and Hold Timings
Valid delay and float timings are given for output signals
during functional operation and are given relative to the rising
edge of CLK. During boundary-scan testing, valid delay and
float timings for output signals are with respect to the falling
edge of TCK. The maximum valid delay timings are provided to
allow a system designer to determine if setup times to the
system logic can be met. Likewise, the minimum valid delay
timings are used to analyze hold times to the system logic.
The setup and hold time requirements for the AMD-K6
processor input signals must be met by the system logic to
assure the proper operation of the AMD-K6. The setup and
hold timings during functional and boundary-scan test mode
are given relative to the rising edge of CLK and TCK,
respectively.
Chapter 16
Signal Switching Characteristics
243
Preliminary Information
AMD-K6® Processor Data Sheet
16.5
20695H/0—March 1998
Output Delay Timings for 66-MHz Bus Operation
Table 49. Output Delay Timings for 66-MHz Bus Operation
Symbol
244
Parameter Description
Preliminary Data
Figure
Min
Max
1.1 ns
6.3 ns
84
10.0 ns
85
6.0 ns
84
10.0 ns
85
7.0 ns
84
10.0 ns
85
8.5 ns
84
10.0 ns
85
t6
A[31:3] Valid Delay
t7
A[31:3] Float Delay
t8
ADS# Valid Delay
t9
ADS# Float Delay
t10
ADSC# Valid Delay
t11
ADSC# Float Delay
t12
AP Valid Delay
t13
AP Float Delay
t14
APCHK# Valid Delay
1.0 ns
8.3 ns
84
t15
BE[7:0]# Valid Delay
1.0 ns
7.0 ns
84
t16
BE[7:0]# Float Delay
10.0 ns
85
t17
BREQ Valid Delay
1.0 ns
8.0 ns
84
t18
CACHE# Valid Delay
1.0 ns
7.0 ns
84
t19
CACHE# Float Delay
10.0 ns
85
t20
D/C# Valid Delay
7.0 ns
84
t21
D/C# Float Delay
10.0 ns
85
t22
D[63:0] Write Data Valid Delay
7.5 ns
84
t23
D[63:0] Write Data Float Delay
10.0 ns
85
t24
DP[7:0] Write Data Valid Delay
7.5 ns
84
t25
DP[7:0] Write Data Float Delay
10.0 ns
85
t26
FERR# Valid Delay
1.0 ns
8.3 ns
84
t27
HIT# Valid Delay
1.0 ns
6.8 ns
84
t28
HITM# Valid Delay
1.1 ns
6.0 ns
84
t29
HLDA Valid Delay
1.0 ns
6.8 ns
84
t30
LOCK# Valid Delay
1.1 ns
7.0 ns
84
t31
LOCK# Float Delay
10.0 ns
85
t32
M/IO# Valid Delay
5.9 ns
84
t33
M/IO# Float Delay
10.0 ns
85
1.0 ns
1.0 ns
1.0 ns
1.0 ns
1.3 ns
1.3 ns
1.0 ns
Signal Switching Characteristics
Comments
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 49. Output Delay Timings for 66-MHz Bus Operation (continued)
Symbol
Parameter Description
Preliminary Data
Figure
Min
Max
1.0 ns
7.0 ns
84
10.0 ns
85
t34
PCD Valid Delay
t35
PCD Float Delay
t36
PCHK# Valid Delay
1.0 ns
7.0 ns
84
t37
PWT Valid Delay
1.0 ns
7.0 ns
84
t38
PWT Float Delay
10.0 ns
85
t39
SCYC Valid Delay
7.0 ns
84
t40
SCYC Float Delay
10.0 ns
85
t41
SMIACT# Valid Delay
1.0 ns
7.3 ns
84
t42
W/R# Valid Delay
1.0 ns
7.0 ns
84
t43
W/R# Float Delay
10.0 ns
85
Chapter 16
1.0 ns
Signal Switching Characteristics
Comments
245
Preliminary Information
AMD-K6® Processor Data Sheet
16.6
20695H/0—March 1998
Input Setup and Hold Timings for 66-MHz Bus Operation
Table 50. Input Setup and Hold Timings for 66-MHz Bus Operation
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Comments
t44
A[31:5] Setup Time
6.0 ns
86
t45
A[31:5] Hold Time
1.0 ns
86
t46
A20M# Setup Time
5.0 ns
86
Note 1
t47
A20M# Hold Time
1.0 ns
86
Note 1
t48
AHOLD Setup Time
5.5 ns
86
t49
AHOLD Hold Time
1.0 ns
86
t50
AP Setup Time
5.0 ns
86
t51
AP Hold Time
1.0 ns
86
t52
BOFF# Setup Time
5.5 ns
86
t53
BOFF# Hold Time
1.0 ns
86
t54
BRDY# Setup Time
5.0 ns
86
t55
BRDY# Hold Time
1.0 ns
86
t56
BRDYC# Setup Time
5.0 ns
86
t57
BRDYC# Hold Time
1.0 ns
86
t58
D[63:0] Read Data Setup Time
2.8 ns
86
t59
D[63:0] Read Data Hold Time
1.5 ns
86
t60
DP[7:0] Read Data Setup Time
2.8 ns
86
t61
DP[7:0] Read Data Hold Time
1.5 ns
86
t62
EADS# Setup Time
5.0 ns
86
t63
EADS# Hold Time
1.0 ns
86
t64
EWBE# Setup Time
5.0 ns
86
t65
EWBE# Hold Time
1.0 ns
86
t66
FLUSH# Setup Time
5.0 ns
86
Note 2
t67
FLUSH# Hold Time
1.0 ns
86
Note 2
Notes:
1. These level-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must be asserted for a minimum pulse width of two clocks.
2. These edge-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must have been negated at least two clocks prior to assertion and must
remain asserted at least two clocks.
246
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 50. Input Setup and Hold Timings for 66-MHz Bus Operation (continued)
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Comments
t68
HOLD Setup Time
5.0 ns
86
t69
HOLD Hold Time
1.5 ns
86
t70
IGNNE# Setup Time
5.0 ns
86
Note 1
t71
IGNNE# Hold Time
1.0 ns
86
Note 1
t72
INIT Setup Time
5.0 ns
86
Note 2
t73
INIT Hold Time
1.0 ns
86
Note 2
t74
INTR Setup Time
5.0 ns
86
Note 1
t75
INTR Hold Time
1.0 ns
86
Note 1
t76
INV Setup Time
5.0 ns
86
t77
INV Hold Time
1.0 ns
86
t78
KEN# Setup Time
5.0 ns
86
t79
KEN# Hold Time
1.0 ns
86
t80
NA# Setup Time
4.5 ns
86
t81
NA# Hold Time
1.0 ns
86
t82
NMI Setup Time
5.0 ns
86
Note 2
t83
NMI Hold Time
1.0 ns
86
Note 2
t84
SMI# Setup Time
5.0 ns
86
Note 2
t85
SMI# Hold Time
1.0 ns
86
Note 2
t86
STPCLK# Setup Time
5.0 ns
86
Note 1
t87
STPCLK# Hold Time
1.0 ns
86
Note 1
t88
WB/WT# Setup Time
4.5 ns
86
t89
WB/WT# Hold Time
1.0 ns
86
Notes:
1. These level-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must be asserted for a minimum pulse width of two clocks.
2. These edge-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must have been negated at least two clocks prior to assertion and must
remain asserted at least two clocks.
Chapter 16
Signal Switching Characteristics
247
Preliminary Information
AMD-K6® Processor Data Sheet
16.7
20695H/0—March 1998
Output Delay Timings for 60-MHz Bus Operation
Table 51. Output Delay Timings for 60-MHz Bus Operation
Symbol
248
Parameter Description
Preliminary Data
Figure
Min
Max
1.1 ns
6.3 ns
84
10.0 ns
85
7.0 ns
84
10.0 ns
85
7.0 ns
84
10.0 ns
85
8.5 ns
84
10.0 ns
85
t6
A[31:3] Valid Delay
t7
A[31:3] Float Delay
t8
ADS# Valid Delay
t9
ADS# Float Delay
t10
ADSC# Valid Delay
t11
ADSC# Float Delay
t12
AP Valid Delay
t13
AP Float Delay
t14
APCHK# Valid Delay
1.0 ns
8.3 ns
84
t15
BE[7:0]# Valid Delay
1.0 ns
7.0 ns
84
t16
BE[7:0]# Float Delay
10.0 ns
85
t17
BREQ Valid Delay
1.0 ns
8.0 ns
84
t18
CACHE# Valid Delay
1.0 ns
7.0 ns
84
t19
CACHE# Float Delay
10.0 ns
85
t20
D/C# Valid Delay
7.0 ns
84
t21
D/C# Float Delay
10.0 ns
85
t22
D[63:0] Write Data Valid Delay
7.5 ns
84
t23
D[63:0] Write Data Float Delay
10.0 ns
85
t24
DP[7:0] Write Data Valid Delay
7.5 ns
84
t25
DP[7:0] Write Data Float Delay
10.0 ns
85
t26
FERR# Valid Delay
1.0 ns
8.3 ns
84
t27
HIT# Valid Delay
1.0 ns
8.0 ns
84
t28
HITM# Valid Delay
1.1 ns
6.0 ns
84
t29
HLDA Valid Delay
1.0 ns
8.0 ns
84
t30
LOCK# Valid Delay
1.1 ns
7.0 ns
84
t31
LOCK# Float Delay
10.0 ns
85
t32
M/IO# Valid Delay
7.0 ns
84
t33
M/IO# Float Delay
10.0 ns
85
1.0 ns
1.0 ns
1.0 ns
1.0 ns
1.3 ns
1.3 ns
1.0 ns
Signal Switching Characteristics
Comments
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 51. Output Delay Timings for 60-MHz Bus Operation (continued)
Symbol
Parameter Description
Preliminary Data
Figure
Min
Max
1.0 ns
7.0 ns
84
10.0 ns
85
t34
PCD Valid Delay
t35
PCD Float Delay
t36
PCHK# Valid Delay
1.0 ns
7.0 ns
84
t37
PWT Valid Delay
1.0 ns
7.0 ns
84
t38
PWT Float Delay
10.0 ns
85
t39
SCYC Valid Delay
7.0 ns
84
t40
SCYC Float Delay
10.0 ns
85
t41
SMIACT# Valid Delay
1.0 ns
7.6 ns
84
t42
W/R# Valid Delay
1.0 ns
7.0 ns
84
t43
W/R# Float Delay
10.0 ns
85
Chapter 16
1.0 ns
Signal Switching Characteristics
Comments
249
Preliminary Information
AMD-K6® Processor Data Sheet
16.8
20695H/0—March 1998
Input Setup and Hold Timings for 60-MHz Bus Operation
Table 52. Input Setup and Hold Timings for 60-MHz Bus Operation
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Comments
t44
A[31:5] Setup Time
6.0 ns
86
t45
A[31:5] Hold Time
1.0 ns
86
t46
A20M# Setup Time
5.0 ns
86
Note 1
t47
A20M# Hold Time
1.0 ns
86
Note 1
t48
AHOLD Setup Time
5.5 ns
86
t49
AHOLD Hold Time
1.0 ns
86
t50
AP Setup Time
5.0 ns
86
t51
AP Hold Time
1.0 ns
86
t52
BOFF# Setup Time
5.5 ns
86
t53
BOFF# Hold Time
1.0 ns
86
t54
BRDY# Setup Time
5.0 ns
86
t55
BRDY# Hold Time
1.0 ns
86
t56
BRDYC# Setup Time
5.0 ns
86
t57
BRDYC# Hold Time
1.0 ns
86
t58
D[63:0] Read Data Setup Time
3.0 ns
86
t59
D[63:0] Read Data Hold Time
1.5 ns
86
t60
DP[7:0] Read Data Setup Time
3.0 ns
86
t61
DP[7:0] Read Data Hold Time
1.5 ns
86
t62
EADS# Setup Time
5.5 ns
86
t63
EADS# Hold Time
1.0 ns
86
t64
EWBE# Setup Time
5.0 ns
86
t65
EWBE# Hold Time
1.0 ns
86
t66
FLUSH# Setup Time
5.0 ns
86
Note 2
t67
FLUSH# Hold Time
1.0 ns
86
Note 2
Notes:
1. These level-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must be asserted for a minimum pulse width of two clocks.
2. These edge-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must have been negated at least two clocks prior to assertion and must
remain asserted at least two clocks.
250
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 52. Input Setup and Hold Timings for 60-MHz Bus Operation (continued)
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Comments
t68
HOLD Setup Time
5.0 ns
86
t69
HOLD Hold Time
1.5 ns
86
t70
IGNNE# Setup Time
5.0 ns
86
Note 1
t71
IGNNE# Hold Time
1.0 ns
86
Note 1
t72
INIT Setup Time
5.0 ns
86
Note 2
t73
INIT Hold Time
1.0 ns
86
Note 2
t74
INTR Setup Time
5.0 ns
86
Note 1
t75
INTR Hold Time
1.0 ns
86
Note 1
t76
INV Setup Time
5.0 ns
86
t77
INV Hold Time
1.0 ns
86
t78
KEN# Setup Time
5.0 ns
86
t79
KEN# Hold Time
1.0 ns
86
t80
NA# Setup Time
4.5 ns
86
t81
NA# Hold Time
1.0 ns
86
t82
NMI Setup Time
5.0 ns
86
Note 2
t83
NMI Hold Time
1.0 ns
86
Note 2
t84
SMI# Setup Time
5.0 ns
86
Note 2
t85
SMI# Hold Time
1.0 ns
86
Note 2
t86
STPCLK# Setup Time
5.0 ns
86
Note 1
t87
STPCLK# Hold Time
1.0 ns
86
Note 1
t88
WB/WT# Setup Time
4.5 ns
86
t89
WB/WT# Hold Time
1.0 ns
86
Notes:
1. These level-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must be asserted for a minimum pulse width of two clocks.
2. These edge-sensitive signals can be asserted synchronously or asynchronously. To be sampled on a specific clock edge, setup and
hold times must be met. If asserted asynchronously, they must have been negated at least two clocks prior to assertion and must
remain asserted at least two clocks.
Chapter 16
Signal Switching Characteristics
251
Preliminary Information
AMD-K6® Processor Data Sheet
16.9
20695H/0—March 1998
RESET and Test Signal Timing
Table 53. RESET and Configuration Signals (60-MHz and 66-MHz Operation)
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Comments
t90
RESET Setup Time
5.0 ns
87
t91
RESET Hold Time
1.0 ns
87
t92
RESET Pulse Width, VCC and CLK Stable
15 clocks
87
t93
RESET Active After VCC and CLK Stable
1.0 ms
87
t94
BF[2:0] Setup Time
1.0 ms
87
Note 3
t95
BF[2:0] Hold Time
2 clocks
87
Note 3
t96
BRDYC# Hold Time
1.0 ns
87
Note 4
t97
BRDYC# Setup Time
2 clocks
87
Note 2
t98
BRDYC# Hold Time
2 clocks
87
Note 2
t99
FLUSH# Setup Time
5.0 ns
87
Note 1
t100
FLUSH# Hold Time
1.0 ns
87
Note 1
t101
FLUSH# Setup Time
2 clocks
87
Note 2
t102
FLUSH# Hold Time
2 clocks
87
Note 2
Notes:
1. To be sampled on a specific clock edge, setup and hold times must be met the clock edge before the clock edge on which RESET
is sampled negated.
2. If asserted asynchronously, these signals must meet a minimum setup and hold time of two clocks relative to the negation of
RESET.
3. BF[2:0] must meet a minimum setup time of 1.0 ms and a minimum hold time of two clocks relative to the negation of RESET.
4. If RESET is driven synchronously, BRDYC# must meet the specified hold time relative to the negation of RESET.
252
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Table 54. TCK Waveform and TRST# Timing at 25 MHz
Symbol
Parameter Description
Preliminary Data
Min
TCK Frequency
Max
Figure
25 MHz
Comments
88
t103
TCK Period
40.0 ns
88
t104
TCK High Time
14.0 ns
88
t105
TCK Low Time
14.0 ns
88
t106
TCK Fall Time
5.0 ns
88
Note 1, 2
t107
TCK Rise Time
5.0 ns
88
Note 1, 2
t108
TRST# Pulse Width
89
Asynchronous
30.0 ns
Notes:
1. Rise/Fall times can be increased by 1.0 ns for each 10 MHz that TCK is run below its maximum frequency of 25 MHz.
2. Rise/Fall times are measured between 0.8 V and 2.0 V.
Table 55. Test Signal Timing at 25 MHz
Symbol
Parameter Description
Preliminary Data
Min
Max
Figure
Notes
t109
TDI Setup Time
5.0 ns
90
Note 2
t110
TDI Hold Time
9.0 ns
90
Note 2
t111
TMS Setup Time
5.0 ns
90
Note 2
t112
TMS Hold Time
9.0 ns
90
Note 2
t113
TDO Valid Delay
3.0 ns
13.0 ns
90
Note 1
t114
TDO Float Delay
16.0 ns
90
Note 1
t115
All Outputs (Non-Test) Valid Delay
13.0 ns
90
Note 1
t116
All Outputs (Non-Test) Float Delay
16.0 ns
90
Note 1
t117
All Inputs (Non-Test) Setup Time
5.0 ns
90
Note 2
t118
All Inputs (Non-Test) Hold Time
9.0 ns
90
Note 2
3.0 ns
Notes:
1. Parameter is measured from the TCK falling edge.
2. Parameter is measured from the TCK rising edge.
Chapter 16
Signal Switching Characteristics
253
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
WAVEFORM
INPUTS
OUTPUTS
Must be steady
Steady
Can change from
High to Low
Changing from High to Low
Can change
from Low to High
Changing from Low to High
Don’t care, any
change permitted
Changing, State Unknown
(Does not apply)
Center line is high
impedance state
Figure 83. Diagrams Key
Tx
Tx
CLK
1.5 V
Max
tv
Output Signal
Min
Valid n
Valid n +1
v = 6, 8, 10, 12, 14, 15, 17, 18, 20, 22, 24, 26, 27, 28, 29, 30, 32, 34, 36, 37, 39, 41, 42
Figure 84. Output Valid Delay Timing
254
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
CLK
Tx
1.5 V
Tx
Tx
Tx
tf
Output Signal
Valid
tv
Min
v = 6, 8, 10, 12, 15, 18, 20, 22, 24, 30, 32, 34, 37, 39, 42
f = 7, 9, 11, 13, 16, 19, 21, 23, 25, 31, 33, 35, 38, 40, 43
Figure 85. Maximum Float Delay Timing
Tx
Tx
Tx
Tx
1.5 V
CLK
ts
th
Input Signal
s = 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88
h = 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89
Figure 86. Input Setup and Hold Timing
Chapter 16
Signal Switching Characteristics
255
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Tx
Tx
CLK
1.5 V
•••
t90
RESET
1.5 V
t91
•••
1.5 V
t92, 93
t99
FLUSH#
(Synchronous)
t100
•••
FLUSH#, BRDYC#
(Asynchronous)
•••
t97, 101
t98, 102
•••
BF[2:0]
(Asynchronous)
t94
t95
Figure 87. Reset and Configuration Timing
256
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
t104
2.0 V
1.5 V
t105
0.8 V
t106
t107
t103
Figure 88. TCK Waveform
t108
1.5 V
Figure 89. TRST# Timing
t103
TCK
1.5 V
t109, 111
t110, 112
TDI, TMS
t114
t113
TDO
t116
t115
Output
Signals
Input
Signals
t117
t118
Figure 90. Test Signal Timing Diagram
Chapter 16
Signal Switching Characteristics
257
Preliminary Information
AMD-K6® Processor Data Sheet
258
20695H/0—March 1998
Signal Switching Characteristics
Chapter 16
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
17
17.1
Thermal Design
Package Thermal Specifications
The AMD-K6 processor operating specification calls for the
case temperature (T C) to be in the range of 0°C to 70°C. The
ambient temperature (TA) is not specified as long as the case
temperature is not violated. The case temperature must be
measured on the top center of the package. Table 56 shows the
AMD-K6 processor thermal specifications.
Table 56. Package Thermal Specification
Maximum Thermal Power
θJC
Junction-Case
TC Case
Temperature
2.9V Component
3.2V Component
166MHz
200MHz
233MHz
17.2 W
20.0 W
28.3 W
Stop Grant Mode
1.45 W
1.53 W
1.75 W
Stop Clock Mode
1.0 W
1.0 W
1.0 W
0°C–70°C
0.77°C/W
Figure 91 on page 260 shows the thermal model of a processor
w it h a p a s sive t h e rm a l so l u t i on . The c a s e -t o -a m b i e n t
temperature (T CA ) can be calculated from the following
equation:
TCA = PMAX • θCA
= PMAX • ( θIF + θSA)
Where:
PMAX
θCA
θIF
θSA
Chapter 17
=
=
=
=
Maximum Power Consumption
Case-to-Ambient Thermal Resistance
Interface Material Thermal Resistance
Sink-to-Ambient Thermal Resistance
Thermal Design
259
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Thermal
Resistance
(°C/W)
Temperature
(Ambient)
TCA
θSA
θCA
Sink
Case
θIF
Figure 91. Thermal Model
Figure 92 illustrates the case-to-ambient temperature (TCA) in
relation to the power consumption (X-axis) and the thermal
resistance (Y-axis). If the power consumption and case
te mpe rat ure are known, t he ther mal re sista nce ( θ C A )
requirement can be calculated for a given ambient temperature
(TA) value.
6.0
T
Thermal Resistance (°C/W)
5.0
CA
15° C
20° C
4.0
25° C
30° C
3.0
2.0
1.0
0.0
6W
9W
12 W
15 W
18 W
Power Consumption (Watts)
Figure 92. Power Consumption vs. Thermal Resistance
260
Thermal Design
Chapter 17
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
The following example calculates the required thermal
resistance of a heatsink:
If:
TC = 70°C
TA = 45°C
PMAX = 20.0W at 200MHz
Then:
 T C – T A
25°C - = 1.25 ( °C ⁄ W )
θ CA ≤  ------------------- = ----------------20.0W
 P MAX 
Thermal grease is recommended as interface material because
it provides the lowest thermal resistance (≅ 0.20°C/W). The
required thermal resistance ( θ SA ) of the heatsink in this
example is calculated as follows:
θSA = θCA – θIF = 1.25 – 0.20 = 1.05 (°C/W)
Heat Dissipation Path
Figure 93 illustrates the processor’s heat dissipation path. Most
of the heat generated by the processor is dissipated from the
top surface (ceramic and lid) of the package. The small amount
of heat generated from the bottom side of the processor where
the processor socket blocks the convection can be safely
ignored.
Ambient Temperature
Thin Lid
Case temperature
Figure 93. Processor Heat Dissipation Path
Chapter 17
Thermal Design
261
Preliminary Information
AMD-K6® Processor Data Sheet
Measuring Case
Temperature
20695H/0—March 1998
The case temperature must be measured on the top center of
the package where most of the heat is dissipated. Figure 94
shows the correct location for measuring the case temperature.
(If a heat exchange device is installed, the thermocouple must
contact the processor top surface through a drilled hole.) The
case temperature is measured to ensure that the thermal
solution meets the operational specification.
Thermocouple
Figure 94. Measuring Case Temperature
17.2
Layout and Airflow Considerations
Voltage Regulator
262
A voltage regulator is required to support the lower voltage
(3.3 V and lower) to the processor. In most applications, the
voltage regulator is designed with power transistors. As a
result, additional heatsinks are required to dissipate the heat
from the power transistors. Figure 95 shows the voltage
regulator placed parallel to the processor with the airflow
aligned with the devices. With this alignment, the heat
generated by the voltage regulator has minimal effect on the
processor.
Thermal Design
Chapter 17
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Voltage Regulator
Processor
Airflow
Figure 95. Voltage Regulator Placement
A heatsink and fan combination can deliver much better
thermal performance than a heatsink alone. More importantly,
with a fan/sink the airflow requirements in a system design are
not as critical. A unidirectional heatsink with a fan moves air
from the top of the heatsink to the side. In this case, the best
location for the voltage regulator is on the side of the processor
in the path of the airflow exiting the fan sink (see Figure 96).
This location guarantees that the heatsinks on both the
processor and the regulator receive adequate air circulation.
Airflow
Ideal areas for voltage regulator
Figure 96. Airflow for a Heatsink with Fan
Chapter 17
Thermal Design
263
Preliminary Information
AMD-K6® Processor Data Sheet
Airflow Management
in a System Design
20695H/0—March 1998
Complete airflow management in a system is important. In
addition to the volume of air, the path of the air is also
important. Figure 97 shows the airflow in a dual-fan system. The
fan in the front end pulls cool air into the system through intake
slots in the chassis. The power supply fan forces the hot air out of
the chassis. The thermal performance of the heatsink can be
maximized if it is located in the shaded area, where it receives
greatest benefit from this air exchange system.
Fan
P/S
Main Board
V
e
n
t
s
Drive Bays
Fan
Vents
Front
Figure 97. Airflow Path in a Dual-fan System
264
Thermal Design
Chapter 17
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Figure 98 shows the airflow management in a system using the
ATX form-factor. The orientation of the power supply fan and
the motherboard are modified in the ATX platform design. The
power supply fan pulls cool air through the chassis and across
the processor. The processor is located near the power supply
fan, where it can receive adequate airflow without an auxiliary
fan. The arrangement significantly improves the airflow across
the processor with minimum installation cost.
Main Board
F
a
n
P/S
Drive Bays
Figure 98. Airflow Path in an ATX Form-Factor System
For more information about thermal solutions, see the
AMD-K6® Processor Thermal Solution Design Application Note,
order# 21085.
Chapter 17
Thermal Design
265
Preliminary Information
AMD-K6® Processor Data Sheet
266
20695H/0—March 1998
Thermal Design
Chapter 17
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
18
Pin Description Diagram
Figure 99. AMD-K6® Processor Top-Side View
Chapter 18
Pin Description Diagram
267
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Figure 100. AMD-K6® Processor Pin-Side View
268
Pin Description Diagram
Chapter 18
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
19
Pin Designations
AMD-K6® Processor Model 6 Functional Grouping
Address
Pin
Name
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30
A31
Pin
No.
AL-35
AM-34
AK-32
AN-33
AL-33
AM-32
AK-30
AN-31
AL-31
AL-29
AK-28
AL-27
AK-26
AL-25
AK-24
AL-23
AK-22
AL-21
AF-34
AH-36
AE-33
AG-35
AJ-35
AH-34
AG-33
AK-36
AK-34
AM-36
AJ-33
Chapter 19
Data
Pin
Name
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D16
D17
D18
D19
D20
D21
D22
D23
D24
D25
D26
D27
D28
D29
D30
D31
D32
D33
D34
D35
D36
D37
D38
D39
D40
D41
D42
D43
D44
D45
D46
D47
D48
D49
D50
D51
D52
D53
D54
D55
D56
D57
D58
D59
D60
D61
D62
D63
Control
Pin
No.
K-34
G-35
J-35
G-33
F-36
F-34
E-35
E-33
D-34
C-37
C-35
B-36
D-32
B-34
C-33
A-35
B-32
C-31
A-33
D-28
B-30
C-29
A-31
D-26
C-27
C-23
D-24
C-21
D-22
C-19
D-20
C-17
C-15
D-16
C-13
D-14
C-11
D-12
C-09
D-10
D-08
A-05
E-09
B-04
D-06
C-05
E-07
C-03
D-04
E-05
D-02
F-04
E-03
G-05
E-01
G-03
H-04
J-03
J-05
K-04
L-05
L-03
M-04
N-03
Pin
Name
A20M#
ADS#
ADSC#
AHOLD
APCHK#
BE0#
BE1#
BE2#
BE3#
BE4#
BE5#
BE6#
BE7#
BF0
BF1
BF2
BOFF#
BRDY#
BRDYC#
BREQ
CACHE#
CLK
D/C#
EADS#
EWBE#
FERR#
FLUSH#
HIT#
HITM#
HLDA
HOLD
IGNNE#
INIT
INTR
INV
KEN#
LOCK#
M/IO#
NA#
NMI
PCD
PCHK#
PWT
RESET
SCYC
SMI#
SMIACT#
STPCLK#
VCC2DET
W/R#
WB/WT#
Test
Pin
No.
AK-08
AJ-05
AM-02
V-04
AE-05
AL-09
AK-10
AL-11
AK-12
AL-13
AK-14
AL-15
AK-16
Y-33
X-34
W-35
Z-04
X-04
Y-03
AJ-01
U-03
AK-18
AK-04
AM-04
W-03
Q-05
AN-07
AK-06
AL-05
AJ-03
AB-04
AA-35
AA-33
AD-34
U-05
W-05
AH-04
T-04
Y-05
AC-33
AG-05
AF-04
AL-03
AK-20
AL-17
AB-34
AG-03
V-34
AL-01
AM-06
AA-05
Pin
Name
TCK
TDI
TDO
TMS
TRST#
Pin
No.
M-34
N-35
N-33
P-34
Q-33
Parity
AP
DP0
DP1
DP2
DP3
DP4
DP5
DP6
DP7
AK-02
D-36
D-30
C-25
D-18
C-07
F-06
F-02
N-05
Pin Designations
NC
Vcc2
Vcc3
Vss
Pin
No.
Pin
No.
Pin
No.
Pin
No.
A-37
E-17
E-25
R-34
S-33
S-35
W-33
AJ-15
AJ-23
AL-19
AN-35
A-07
A-09
A-11
A-13
A-15
A-17
B-02
E-15
G-01
J-01
L-01
N-01
Q-01
S-01
U-01
W-01
Y-01
AA-01
AC-01
AE-01
AG-01
AJ-11
AN-09
AN-11
AN-13
AN-15
AN-17
AN-19
A-19
A-21
A-23
A-25
A-27
A-29
E-21
E-27
E-37
G-37
J-37
L-33
L-37
N-37
Q-37
S-37
T-34
U-33
U-37
W-37
Y-37
AA-37
AC-37
AE-37
AG-37
AJ-19
AJ-29
AN-21
AN-23
AN-25
AN-27
AN-29
INC
C-01
H-34
Y-35
Z-34
AC-35
AL-07
AN-01
AN-03
AN-05
RSVD
J-33
L-35
P-04
Q-03
Q-35
R-04
S-03
S-05
AA-03
AC-03
AC-05
AD-04
AE-03
AE-35
KEY
AH-32
A-03
B-06
B-08
B-10
B-12
B-14
B-16
B-18
B-20
B-22
B-24
B-26
B-28
E-11
E-13
E-19
E-23
E-29
E-31
H-02
H-36
K-02
K-36
M-02
M-36
P-02
P-36
R-02
R-36
T-02
T-36
U-35
V-02
V-36
X-02
X-36
Z-02
Z-36
AB-02
AB-36
AD-02
AD-36
AF-02
AF-36
AH-02
AJ-07
AJ-09
AJ-13
AJ-17
AJ-21
AJ-25
AJ-27
AJ-31
AJ-37
AL-37
AM-08
AM-10
AM-12
AM-14
AM-16
AM-18
AM-20
AM-22
AM-24
AM-26
AM-28
AM-30
AN-37
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Pin Designations
Chapter 19
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
20
Package Specifications
20.1
321-Pin Staggered CPGA Package Specification
Table 57. 321-Pin Staggered CPGA Package Specification
Symbol
Millimeters
Min
Max
A
49.28
B
Inches
Min
Max
49.78
1.940
1.960
45.59
45.85
1.795
1.805
C
31.32
32.59
1.233
1.283
D
44.90
45.10
1.768
1.776
E
2.91
3.63
0.115
0.143
F
1.30
1.52
0.051
0.060
G
3.05
3.30
0.120
0.130
H
0.43
0.51
0.017
0.020
M
2.29
2.79
0.090
0.110
N
1.14
1.40
0.045
0.055
d
1.52
2.29
0.060
0.090
e
1.52
2.54
0.060
0.100
f
—
0.13
—
0.005
Chapter 20
Notes
Flatness
Package Specifications
Notes
Flatness
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Figure 101. 321-Pin Staggered CPGA Package Specification
272
Package Specifications
Chapter 20
Preliminary Information
AMD-K6® Processor Data Sheet
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21
Ordering Information
Standard Products
AMD standard products are available in several operating ranges. The ordering part
number (OPN) is formed by a combination of the elements below.
AMD-K6 -233
A N R
Case Temperature
R = 0°C–70°C
Operating Voltage
N = 3.1 V–3.3 V (Core) / 3.135 V–3.6 V (I/O)
L = 2.755 V–3.045 V (Core) / 3.135 V–3.6 V (I/O)
Package Type
A = 321-pin CPGA
Performance Rating
-233
-200
-166
Family/Core
AMD-K6
Table 58. Valid Ordering Part Number Combinations
OPN
Package Type
AMD-K6-233ANR
321-pin CPGA
AMD-K6-200ALR
321-pin CPGA
AMD-K6-166ALR
321-pin CPGA
Operating Voltage
3.1V–3.3V (Core)
3.135V–3.6V (I/O)
2.755V–3.045V (Core)
3.135V–3.6V (I/O)
2.755V–3.045V (Core)
3.135V–3.6V (I/O)
Case Temperature
0°C–70°C
0°C–70°C
0°C–70°C
Notes:
This table lists configurations planned to be supported in volume for this device. Consult the local
AMD sales office to confirm availability of specific valid combinations and to check on
newly-released combinations.
Chapter 21
Ordering Information
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Ordering Information
Chapter 21
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Part Two
AMD-K6 ®
Processor Model 7
The AMD-K6® Processor Data Sheet supports the Model 6 and
Model 7 versions of the AMD-K6 processor family. Model 6
refers to the AMD-K6 manufactured with 0.35-micron process
technology and Model 7 refers to the AMD-K6 manufactured
with 0.25-micron process technology. Part Two (chapters 22–42)
contains information regarding new specifications and
differences that pertain only to Model 7 as compared to Model
6.
Part Two
AMD-K6® Processor Model 7
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AMD-K6® Processor Model 7
Part Two
Preliminary Information
AMD-K6® Processor Data Sheet
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22
■
■
■
■
■
■
■
■
■
AMD-K6® Processor
Advanced 6-Issue RISC86® Superscalar Microarchitecture
◆ Seven parallel specialized execution units
◆ Multiple sophisticated x86-to-RISC86 instruction decoders
◆ Advanced two-level branch prediction
◆ Speculative execution
◆ Out-of-order execution
◆ Register renaming and data forwarding
◆ Issues up to six RISC86 instructions per clock
Large On-Chip Split 64-Kbyte Level-One (L1) Cache
◆ 32-Kbyte instruction cache with additional predecode cache
◆ 32-Kbyte writeback dual-ported data cache
◆ MESI protocol support
High-Performance IEEE 754-Compatible and 854-Compatible Floating-Point Unit
High-Performance Industry-Standard MMX™ Instructions
321-Pin Ceramic Pin Grid Array (CPGA) Package (Socket 7 Compatible)
Industry-Standard System Management Mode (SMM)
IEEE 1149.1 Boundary Scan
Full x86 Binary Software Compatibility
0.25-Micron Process Technology
AMD continues to deliver leading-edge processor solutions by advancing the highly
successful AMD-K6® processor with state-of-the-art 0.25-micron process technology.
The AMD-developed 0.25-micron process technology enables the AMD-K6 processor
to deliver higher performance with a lower core voltage and lower power dissipation.
This new version of the AMD-K6 processor continues to leverage today’s cost-effective
infrastructure to deliver a superior price/performance PC solution.
To provide industry-leading performance, the AMD-K6 processor incorporates the
innovative and efficient RISC86 microarchitecture, a large 64-Kbyte level-one cache
(32-Kbyte dual-ported data cache, 32-Kbyte instruction cache with predecode data), a
powerful IEEE 754-compatible and 854-compatible floating-point execution unit, and
a high-performance multimedia execution unit for executing industry-standard MMX
instructions. These features have been combined to deliver industry leadership in
16-bit and 32-bit performance, providing exceptional performance for both Windows®
95 and Windows NT™ software bases.
Chapter 22
AMD-K6® Processor
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The AMD-K6 processor’s RISC86 microarchitecture is a decoupled decode/execution
superscalar design that implements state-of-the-art design techniques to achieve
leading-edge performance. Advanced design techniques implemented in the AMD-K6
include multiple x86 instruction decode, single-clock internal RISC operations, seven
execution units that support superscalar operation, out-of-order execution, data
forwarding, speculative execution, and register renaming. In addition, the processor
supports the industry’s most advanced branch prediction logic by implementing an
8192-entry branch history table, the industry’s only branch target cache, and a return
address stack, which combine to deliver better than a 95% prediction rate. These
design techniques enable the AMD-K6 processor to issue, execute, and retire
multiple x86 instructions per clock, resulting in excellent scaleable performance.
The AMD-K6 processor is fully x86 binary code compatible. AMD’s extensive
experience through four generations of x86 processors has been carefully integrated
into the AMD-K6 to provide complete compatibility with Windows 95, Windows 3.x,
Windows NT, DOS, OS/2, Unix, Solaris, NetWare® , Vines, and other leading x86
operating systems and applications. The AMD-K6 processor is Socket 7 compatible,
allowing the processor to be quickly and easily integrated into a mature and
cost-effective industry-standard infrastructure of motherboards, chipsets, power
supplies, and thermal designs.
AMD has designed, manufactured, and delivered over 50 million Microsoft
Windows-compatible processors in the last five years alone. The AMD-K6 processor is
the next addition to this long line of processors. With its combination of
state-of-the-art features, industry-leading performance, high-performance
multimedia engine, full x86 compatibility, and low-cost infrastructure, the AMD-K6 is
the superior choice for mainstream personal computers.
278
AMD-K6® Processor
Chapter 22
Preliminary Information
AMD-K6® Processor Data Sheet
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23
Internal Architecture
The internal architecture of the AMD-K6 processor remains
unchanged with the integration of 0.25-micron process
technology. For information about the internal architecture of
the AMD-K6 processor Model 7, see Chapter 2, “Internal
Architecture” on page 7.
Chapter 23
Internal Architecture
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Internal Architecture
Chapter 23
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
24
Software Environment
This chapter briefly describes the AMD-K6 Model-Specific
Registers (MSRs) and x86 instructions supported by the
AMD-K6 processor Model 7 that are not supported by the
AMD-K6 processor Model 6.
For an overview of the AMD-K6 processor’s x86 software
environment and a description of the remaining data types,
registers, operating modes, interrupts, and instructions
s u p p o r t e d by t h e A M D -K 6 a rch i t e c t u re a n d d e s i g n
implementation, see Chapter 3, “Software Environment” on
page 21.
24.1
Registers
The AMD-K6 processor contains all the registers defined by the
x86 architecture, including general-purpose, segment,
floating-point, MMX, EFLAGS, control, task, debug, test, and
descriptor/memory-management registers.
This section provides information on the Model-Specific
Registers (MSRs) supported by the AMD-K6 processor Model 7
that are not supported by the AMD-K6 processor Model 6. For
information about the remaining AMD-K6 registers, see
Chapter 3, “Software Environment” on page 21.
Note: Areas of the register designated as Reserved should not be
modified by software.
Model-Specific
Registers (MSR)
Chapter 24
The AMD-K6 processor Model 7 supports two additional MSRs
as compared to the AMD-K6 processor Model 6. The value in the
ECX register selects the MSR to be addressed by the RDMSR
and WRMSR instructions. The values in EAX and EDX are used
as inputs and outputs by the RDMSR and WRMSR instructions.
Table 59 lists the new MSRs and the corresponding value of the
ECX register. Figures 102 and 103 show the MSR formats.
Software Environment
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Table 59. Model-Specific Registers (MSRs)
Model-Specific Register
Value of ECX
Extended Feature Enable Register (EFER)
C000_0080h
SYSCALL/SYSRET Target Address Register (STAR)
C000_0081h
For mo re info rma tio n abo ut the RD MSR and WRMSR
instructions, see the AMD K86™ Family BIOS and Software Tools
Development Guide, order# 21062.
Extended Feature Enable Register (EFER). T h e E x t e n d e d Fe a t u re
Enable Register (EFER) contains the control bits that enable
the extended features of the AMD-K6. Figure 102 shows the
format of the EFER register, and Table 60 defines the function
of each bit in the EFER register.
63
1
0
S
C
E
Reserved
Symbol
Description
SCE
System Call/Return Extension
Bit
0
Figure 102. Extended Feature Enable Register (EFER)
Table 60. Extended Feature Enable Register (EFER) Definition
Bit
63–1
0
Description
Reserved
System Call/Return Extension (SCE)
R/W
R
R/W
SYSCALL/SYSRET Target Address Register (STAR).
The SYSCALL/SYSRET Target Address Register (STAR)
contains the target EIP address used by the SYSCALL
instruction and the 16-bit code and stack segment selector
bases used by the SYSCALL and SYSRET instructions. Figure
103 shows the format of the STAR register, and Table 61 defines
the function of each bit of the STAR register. For more
information, see the SYSCALL and SYSRET Instruction
Specification Application Note, order# 21086.
282
Software Environment
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Preliminary Information
AMD-K6® Processor Data Sheet
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63
32 31
48 47
SYSRET CS Selector and SS
Selector Base
0
SYSCALL CS Selector and SS
Selector Base
Target EIP Address
Figure 103. SYSCALL/SYSRET Target Address Register (STAR)
Table 61. SYSCALL/SYSRET Target Address Register (STAR) Definition
Bit
Description
R/W
63–48
SYSRET CS and SS Selector Base
R/W
47–32
SYSCALL CS and SS Selector Base
R/W
31–0
Target EIP Address
R/W
Instructions Supported by the AMD-K6® Processor
24.2
This section documents the x86 instructions supported by the
AMD-K6 processor Model 7 that are not supported by AMD-K6
processor Model 6. For information about the remaining x86
instructions supported by the AMD-K6 processor Model 6, see
Chapter 3, “Software Environment” on page 21.
Table 62 shows the instruction mnemonic, opcode, modR/M
by t e , d e c o d e t y p e, a n d R I S C 8 6 o p e ra t i o n ( s ) fo r e a ch
instruction. The first column of the tables indicates the
instruction mnemonic and operand types. The second and third
columns list all applicable opcode bytes. The fourth column
lists the modR/M byte when used by the instruction. The
modR/M byte defines the instruction as a register or memory
form. The fifth column lists the type of instruction decode —
short, long, and vector. The sixth column lists the type of
RISC86 operation(s) required for the instruction.
Table 62. Integer Instructions
First
Byte
Second
Byte
SYSCALL
0Fh
05h
vector
SYSRET
0Fh
07h
vector
Instruction Mnemonic
Chapter 24
ModR/M
Byte
Software Environment
Decode
Type
RISC86®
Opcodes
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Software Environment
Chapter 24
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
25
Logic Symbol Diagram
Clock
CLK
Bus
Arbitration
Address
and
Address
Parity
Cycle
Definition
and
Control
Cache
Control
Voltage Detection
BF[2:0]
VCC2DET VCC2H/L#
AHOLD
BOFF#
BREQ
HLDA
HOLD
A20M#
A[31:3]
AP
ADS#
ADSC#
APCHK#
BE[7:0]#
AMD-K6®
D/C#
EWBE#
LOCK#
M/IO#
NA#
SCYC
W/R#
Processor
Model 7
CACHE#
KEN#
PCD
PWT
WB/WT#
TCK
TDI
TDO
BRDY#
BRDYC#
D[63:0]
DP[7:0]
PCHK#
Data
and
Data
Parity
EADS#
HIT#
HITM#
INV
Inquire
Cycles
FERR#
IGNNE#
Floating-Point
Error Handling
FLUSH#
INIT
INTR
NMI
RESET
SMI#
SMIACT#
STPCLK#
External
Interrupts,
SMM, Reset and
Initialization
TMS TRST#
JTAG Test
Chapter 25
Logic Symbol Diagram
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Logic Symbol Diagram
Chapter 25
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
26
Signal Descriptions
This chapter provides a description of the signals designed to
i n d i c a t e t o s y s t e m l o g i c t h e s p e c i f i e d d u a l -vo l t a g e
re q u ire m e n t s o f t h e A M D -K 6 p ro c e ss o r M o d e l 7 . Fo r
information about the remaining AMD-K6 processor Model 7
signals, see Chapter 5, “Signal Descriptions” on page 79.
26.1
VCC2DET (VCC2 Detect)
Output
Summary
VCC2DET is internally tied to VSS (logic level 0) to indicate to
the system logic that it must supply the specified dual-voltage
requirements to the VCC2 and VCC3 pins. The VCC2 pins supply
voltage to the processor core, independent of the voltage
supplied to the I/O buffers on the V CC3 pins. Upon sampling
VCC2DET Low, system logic should sample VCC2H/L# to
identify core voltage requirements.
Driven
VCC2DET always equals 0 and is never floated—even during
Tri-State Test mode.
26.2
VCC2H/L# (VCC2 High/Low)
Output
Summary
VCC2H/L# is internally tied to VSS (logic level 0) to indicate to
the system logic that it must supply the specified processor core
voltage to the VCC2 pins. The VCC2 pins supply voltage to the
processor core, independent of the voltage supplied to the I/O
buffers on the V CC3 pins. Upon sampling VCC2DET Low to
identify dual-voltage processor requirements, system logic
should sample VCC2H/L# to identif y the core voltage
requirements for 2.9 V and 3.2 V products (High) and 2.2 V
products (Low).
Driven
VCC2H/L# always equals 0 and is never floated for 2.2 V
products—even during Tri-State Test mode. To ensure proper
Chapter 26
Signal Descriptions
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operation for 2.9V and 3.2V products, system logic that samples
VCC2H/L# should design a weak pullup resistor for this signal.
Table 63. Output Pin Float Conditions
Name
Floated At:
Note
VCC2DET
Always Driven
*
VCC2H/L#
Always Driven
*
Notes:
*
288
All outputs except VCC2DET, VCC2H/L#, and TDO float
during Tri-State Test mode.
Signal Descriptions
Chapter 26
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
27
Bus Cycles
The timing and relationship of bus signals for the AMD-K6
p ro c e s s o r re m a i n u n ch a n g e d w i t h t h e i n t e g ra t i o n o f
0.25-micron process technology. For information about bus
cycles for the AMD-K6 processor Model 7, see Chapter 6, “Bus
Cycles” on page 121.
Chapter 27
Bus Cycles
289
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AMD-K6® Processor Data Sheet
290
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Bus Cycles
Chapter 27
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
28
Power-on Configuration and Initialization
T h i s ch a p t e r p rov i d e s i n f o r m a t i o n o n t h e p o we r -o n
configuration and initialization states of the AMD-K6 processor
Model 7 that differ from the states of the AMD-K6 processor
M o d e l 6 . Fo r m o re i n f o r m a t i o n a b o u t t h e p o we r -o n
configuration and initialization states of the AMD-K6 processor
Model 7, see Chapt er 7, “ Power-on Conf iguration and
Initialization” on page 167.
28.1
State of Processor After RESET
Output Signals
Table 64 shows the state of processor outputs immediately after
RESET is sampled asserted. The processor outputs shown are
those supported by the AMD-K6 processor Model 7 that are not
supported by the outputs of the AMD-K6 processor Model 6. For
information about the state of the remaining processor outputs
after RESET for the AMD-K6 processor Model 7, see Chapter 7,
“Power-on Configuration and Initialization” on page 167.
Table 64. Output Signal State After RESET
Signal
VCC2H/L#
State
Low
Table 65 on page 292 shows the state of the architecture
register EDX and the Model-Specific Registers EFER and
STAR after the processor has completed its initialization due to
the recognition of RESET. EDX is supported in both the
AMD-K6 processor Model 7 and AMD-K6 processor Model 6.
EFER and STAR are supported only in the AMD-K6 processor
Model 7.
Chapter 28
Power-on Configuration and Initialization
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Table 65. Register State After RESET
Register
State (Hex)
Notes
EDX
0000_057Xh
1
EFER
0000_0000_0000_0000h
2
STAR
0000_0000_0000_0000h
2
Notes:
1. EDX contains the AMD-K6 processor signature, where X indicates the
processor Stepping ID.
2. The contents of these registers are preserved following the recognition
of INIT.
292
Power-on Configuration and Initialization
Chapter 28
Preliminary Information
AMD-K6® Processor Data Sheet
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29
Cache Organization
The internal cache organization of the AMD-K6 processor
remains unchanged with the integration of 0.25-micron process
technology. For information about the cache organization of the
A M D -K 6 p ro c e s s o r M o d e l 7 , s e e C h a p t e r 8 , “ C a c h e
Organization” on page 171.
Chapter 29
Cache Organization
293
Preliminary Information
AMD-K6® Processor Data Sheet
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Cache Organization
Chapter 29
Preliminary Information
20695H/0—March 1998
30
AMD-K6® Processor Data Sheet
Floating-Point and Multimedia Execution Units
The floating-point and multimedia execution units of the
AMD-K6 processor remain unchanged with the integration of
0.25-micron process technology. For information about the
floating-point and multimedia execution units of the AMD-K6
processor Model 7, see Chapter 9, “Floating-Point and
Multimedia Execution Units” on page 189.
Chapter 30
Floating-Point and Multimedia Execution Units
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Preliminary Information
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Floating-Point and Multimedia Execution Units
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Chapter 30
Preliminary Information
AMD-K6® Processor Data Sheet
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31
System Management Mode (SMM)
The implementation of SMM in the AMD-K6 processor remains
unchanged with the integration of 0.25-micron process
technology. For information about the implementation of SMM
in the AMD-K6 processor Model 7, see Chapter 10, “System
Management Mode (SMM)” on page 193.
Chapter 31
System Management Mode (SMM)
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System Management Mode (SMM)
Chapter 31
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
32
Test and Debug
The AMD-K6 processor implements various test and debug
modes to enable the functional and manufacturing testing of
systems and boards that use the processor. In addition, the
debug features of the processor allow designers to debug the
instruction execution of software components. This chapter
describes the following test and debug features of the AMD-K6
processor Model 7 that differ from those supported by the
AMD-K6 processor Model 6:
■
■
Tri-State Test Mode—A test mode that causes the processor
to float its output and bidirectional pins.
Boundary-Scan Test Access Port (TAP)—The Joint Test Action
Group (JTAG) test access function defined by the IEEE
Standard Test Access Port and Boundary-Scan Architecture
(IEEE 1149.1-1990) specification.
For more information about the test and debug modes of the
AMD-K6 processor Model 7, see Chapter 11, “Test and Debug”
on page 203.
32.1
Tri-State Test Mode
The VCC2DET, VCC2H/L#, and TDO signals are the only
outputs not floated in the Tri-State Test mode. VCC2DET and
VCC2H/L# must remain Low to ensure the system continues to
supply the specified processor core voltage to the V CC2 pins.
TDO is never floated because the Boundary-Scan Test Access
Port must remain enabled at all times, including during the
Tri-State Test mode.
The Tri-State Test mode is exited when the processor samples
RESET asserted.
32.2
Boundary-Scan Test Access Port (TAP)
The boundary-scan Test Access Port (TAP) is an IEEE standard
that defines synchronous scanning test methods for complex
logic circuits, such as boards containing a processor. The
AMD-K6 processor supports the TAP standard defined in the
Chapter 32
Test and Debug
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Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
IEEE Standard Test Access Port and Boundary-Scan Architecture
(IEEE 1149.1-1990) specification.
TAP Registers
Device Identification Register (DIR). The DIR is a 32-bit Test Data
Register selected during the execution of the IDCODE
instruction. The fields of the DIR and their values are shown in
Table 66 and are defined as follows:
■
■
■
■
Version Code—This 4-bit field is incremented by AMD
manufacturing for each major revision of silicon.
Part Number—This 16-bit field identifies the specific
processor model.
Manufacturer—This 11-bit field identifies the manufacturer
of the component (AMD).
LSB—The least significant bit (LSB) of the DIR is always set
to 1, as specified by the IEEE 1149.1 standard.
Table 66. Device Identification Register
300
Version Code
(Bits 31–28)
Part Number
(Bits 27–12)
Manufacturer
(Bits 11–1)
LSB
(Bit 0)
Xh
0570h
00000000001b
1b
Test and Debug
Chapter 32
Preliminary Information
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33
Clock Control
The clock control modes of the AMD-K6 processor remain
unchanged with the integration of 0.25-micron process
technology. For information about the clock control modes of
the AMD-K6 processor Model 7, see Chapter 12, “Clock
Control” on page 223.
Chapter 33
Clock Control
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Clock Control
Chapter 33
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34
Power and Grounding
The fundamental power and ground requirements of the
AMD-K6 processor remain unchanged with the integration of
0.25-micron process technology. For information about
decoupling recommendations and pin connection requirements
of the AMD-K6 processor Model 7, see the AMD-K6® Processor
Power Supply Design Application Note, order# 21103 and Chapter
13, “Power and Grounding” on page 229.
34.1
Power Connections
The AMD-K6 processor is a dual voltage device. Two separate
supply voltages are required—VCC2 and VCC3. VCC2 provides the
core voltage for the processor and VCC3 provides the I/O voltage.
See “Electrical Data” on page 233 for the value and range of
VCC2 and VCC3.
There are 28 V CC2, 32 V CC3, and 68 VSS pins on the AMD-K6
processor. (See “Pin Designations” on page 269 for all power
and ground pin designations.) The large number of power and
ground pins are provided to ensure that the processor and
package maintain a clean and stable power distribution
network.
For more information about power connections requirements
for the AMD-K6 processor Model 7, see Chapter 13, “Power and
Grounding” on page 229.
Chapter 34
Power and Grounding
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Power and Grounding
Chapter 34
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35
35.1
Electrical Data
Operating Ranges
The functional operation of the AMD-K6 processor Model 7 is
guaranteed if the voltage and temperature parameters are
within the limits defined in Table 67.
Table 67. Operating Ranges
Parameter
Minimum
Typical
Maximum
Comments
VCC2
2.1 V
2.2 V
2.3 V
Note 1, 2
VCC3
3.135 V
3.30 V
3.6 V
Note 1
TCASE
0°C
70°C
Notes:
1. VCC2 and VCC3 are referenced from VSS.
2. VCC2 specification for 2.2 V components.
35.2
Absolute Ratings
Functional operation of the AMD-K6 processor Model 7 is not
guaranteed beyond the operating ranges listed in Table 67.
Exposure to conditions outside these operating ranges for
extended periods of time can affect long-term reliability.
Permanent damage can occur if the absolute ratings listed in
Table 68 are exceeded.
Table 68. Absolute Ratings
Parameter
Minimum
Maximum
VCC2
–0.5 V
2.5 V
VCC3
–0.5 V
3.6 V
VPIN
–0.5 V
VCC3 + 0.5 V and
≤ 4.0 V
TCASE (under bias)
–65°C
+110°C
TSTORAGE
–65°C
+150°C
Comments
Note
Note:
VPIN (the voltage on any I/O pin) must not be greater than 0.5 V above the voltage being applied
to VCC3. In addition, the VPIN voltage must never exceed 4.0 V.
Chapter 35
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35.3
20695H/0—March 1998
DC Characteristics
The DC characteristics of the AMD-K6 processor Model 7 are
shown in Table 69.
Table 69. DC Characteristics
Symbol
Parameter Description
VIL
Preliminary Data
Comments
Min
Max
Input Low Voltage
–0.3 V
+0.8 V
VIH
Input High Voltage
2.0 V
VCC3 +0.3V
Note 1
VOL
Output Low Voltage
0.4 V
IOL = 4.0-mA load
VOH
Output High Voltage
ICC2
2.2 V Power Supply Current
ICC3
IOH = 3.0-mA load
2.4 V
3.3 V Power Supply Current
5.95 A
200 MHz, Note 2
6.50 A
233 MHz, Note 2
7.05 A
266 MHz, Note 2
7.49 A
300 MHz, Note 2
0.50 A
200 MHz, Note 3
0.52 A
233 MHz, Note 3
0.54 A
266 MHz, Note 3
0.56 A
300 MHz, Note 3
ILI
Input Leakage Current
±15 µA
Note 4
ILO
Output Leakage Current
±15 µA
Note 4
IIL
Input Leakage Current Bias with Pullup
–400 µA
Note 5
IIH
Input Leakage Current Bias with Pulldown
200 µA
Note 6
CIN
Input Capacitance
10 pF
COUT
Output Capacitance
15 pF
COUT
I/O Capacitance
20 pF
CCLK
CLK Capacitance
10 pF
CTIN
Test Input Capacitance (TDI, TMS, TRST#)
10 pF
CTOUT
Test Output Capacitance (TDO)
15 pF
CTCK
TCK Capacitance
10 pF
Notes:
1.
2.
3.
4.
5.
6.
306
VCC3 refers to the voltage being applied to VCC3 during functional operation.
VCC2 = 2.3 V — The maximum power supply current must be taken into account when designing a power supply.
VCC3 = 3.6 V — The maximum power supply current must be taken into account when designing a power supply.
Refers to inputs and I/O without an internal pullup resistor and 0 ≤ VIN ≤ VCC3.
Refers to inputs with an internal pullup and VIL = 0.4 V.
Refers to inputs with an internal pulldown and VIH = 2.4 V.
Electrical Data
Chapter 35
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
35.4
Power Dissipation
Table 70 contains the typical and maximum power dissipation
of the AMD-K6 processor Model 7 during normal and reduced
power states.
Table 70. Typical and Maximum Power Dissipation
Clock Control State
2.2 V Component
Comments
200 MHz
233 MHz
266 MHz
300 MHz
Normal (Maximum Thermal Power)
12.45 W
13.50 W
14.55 W
15.40 W
Note 1, 2
Normal (Typical Thermal Power)
7.50 W
8.10 W
8.75 W
9.25 W
Note 3
Stop Grant / Halt (Maximum)
2.44 W
2.46 W
2.48 W
2.50 W
Note 4
Stop Clock (Maximum)
2.25 W
2.25 W
2.25 W
2.25 W
Note 5
Notes:
1. The maximum power dissipated in the normal clock control state must be taken into account when designing a solution
for thermal dissipation for the AMD-K6 processor.
2. Maximum power is determined for the worst-case instruction sequence or function for the listed clock control states with
VCC2 = 2.2 V and VCC3 = 3.3 V.
3. Typical power is determined for the typical instruction sequences or functions associated with normal system operation with
VCC2 = 2.2 V and VCC3 = 3.3 V.
4. The CLK signal and the internal PLL are still running but most internal clocking has stopped.
5. The CLK signal, the internal PLL, and all internal clocking has stopped.
Chapter 35
Electrical Data
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Electrical Data
Chapter 35
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AMD-K6® Processor Data Sheet
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36
I/O Buffer Characteristics
The I/O buffer characteristics of the AMD-K6 processor Model 7
are different from those of the AMD-K6 processor Model 6.
These differences are minor and are reflected in the I/O Buffer
IBIS Models that are developed for each processor. For the IBIS
models and their application, refer to the AMD-K6® Processor
I/O Model Application Note, order# 21084.
Despite these minor differences, the AC timing specifications
and the DC specifications of the I/O buffers remain unchanged
with the integration of 0.25-micron process technology. For
additional information about the I/O buffer characteristics of
the AMD-K6 processor Model 7, see Chapter 15, “I/O Buffer
Characteristics” on page 237.
Chapter 36
I/O Buffer Characteristics
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310
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I/O Buffer Characteristics
Chapter 36
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
37
Signal Switching Characteristics
The signal switching characteristics of the AMD-K6 processor
remain unchanged with the integration of 0.25-micron process
technology. For information about the signal switching
characteristics of the AMD-K6 processor Model 7, see Chapter
16, “Signal Switching Characteristics” on page 241.
Chapter 37
Signal Switching Characteristics
311
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312
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Signal Switching Characteristics
Chapter 37
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
38
38.1
Thermal Design
Package Thermal Specifications
The AMD-K6 processor Model 7 operating specification calls for
the case temperature (TC) to be in the range of 0°C to 70°C. The
ambient temperature (TA) is not specified as long as the case
temperature is not violated. The case temperature must be
measured on the top center of the package. Table 71 shows the
AMD-K6 processor thermal specifications.
Table 71. Package Thermal Specification
Maximum Thermal Power
TC Case
Temperature
θJC
Junction-Case
2.2 V Component
200 MHz
233 MHz
266 MHz
300 MHz
12.45 W
13.50 W
14.55 W
15.40 W
Stop Grant Mode
2.44 W
2.46 W
2.48 W
2.50 W
Stop Clock Mode
2.25 W
2.25 W
2.25 W
2.25 W
0°C–70°C
1.7 °C/W
For information about thermal solutions, see the AMD-K6 ®
Processor Thermal Solution Design Application Note, order#
21085.
Chapter 38
Thermal Design
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Thermal Design
Chapter 38
Preliminary Information
AMD-K6® Processor Data Sheet
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39
Pin Description Diagram
Figure 104. AMD-K6® Processor Model 7 Top-Side View
Chapter 39
Pin Description Diagram
315
Preliminary Information
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Figure 105. AMD-K6® Processor Model 7 Pin-Side View
316
Pin Description Diagram
Chapter 39
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
40
Pin Designations
AMD-K6® Processor Model 7 Functional Grouping
Address
Pin
Name
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
A27
A28
A29
A30
A31
Pin
No.
AL-35
AM-34
AK-32
AN-33
AL-33
AM-32
AK-30
AN-31
AL-31
AL-29
AK-28
AL-27
AK-26
AL-25
AK-24
AL-23
AK-22
AL-21
AF-34
AH-36
AE-33
AG-35
AJ-35
AH-34
AG-33
AK-36
AK-34
AM-36
AJ-33
Chapter 40
Data
Pin
Name
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D16
D17
D18
D19
D20
D21
D22
D23
D24
D25
D26
D27
D28
D29
D30
D31
D32
D33
D34
D35
D36
D37
D38
D39
D40
D41
D42
D43
D44
D45
D46
D47
D48
D49
D50
D51
D52
D53
D54
D55
D56
D57
D58
D59
D60
D61
D62
D63
Control
Pin
No.
K-34
G-35
J-35
G-33
F-36
F-34
E-35
E-33
D-34
C-37
C-35
B-36
D-32
B-34
C-33
A-35
B-32
C-31
A-33
D-28
B-30
C-29
A-31
D-26
C-27
C-23
D-24
C-21
D-22
C-19
D-20
C-17
C-15
D-16
C-13
D-14
C-11
D-12
C-09
D-10
D-08
A-05
E-09
B-04
D-06
C-05
E-07
C-03
D-04
E-05
D-02
F-04
E-03
G-05
E-01
G-03
H-04
J-03
J-05
K-04
L-05
L-03
M-04
N-03
Pin
Name
A20M#
ADS#
ADSC#
AHOLD
APCHK#
BE0#
BE1#
BE2#
BE3#
BE4#
BE5#
BE6#
BE7#
BF0
BF1
BF2
BOFF#
BRDY#
BRDYC#
BREQ
CACHE#
CLK
D/C#
EADS#
EWBE#
FERR#
FLUSH#
HIT#
HITM#
HLDA
HOLD
IGNNE#
INIT
INTR
INV
KEN#
LOCK#
M/IO#
NA#
NMI
PCD
PCHK#
PWT
RESET
SCYC
SMI#
SMIACT#
STPCLK#
VCC2DET
VCC2H/L#
W/R#
WB/WT#
Test
Pin
No.
AK-08
AJ-05
AM-02
V-04
AE-05
AL-09
AK-10
AL-11
AK-12
AL-13
AK-14
AL-15
AK-16
Y-33
X-34
W-35
Z-04
X-04
Y-03
AJ-01
U-03
AK-18
AK-04
AM-04
W-03
Q-05
AN-07
AK-06
AL-05
AJ-03
AB-04
AA-35
AA-33
AD-34
U-05
W-05
AH-04
T-04
Y-05
AC-33
AG-05
AF-04
AL-03
AK-20
AL-17
AB-34
AG-03
V-34
AL-01
AN-05
AM-06
AA-05
Pin
Name
TCK
TDI
TDO
TMS
TRST#
Pin
No.
M-34
N-35
N-33
P-34
Q-33
Parity
AP
DP0
DP1
DP2
DP3
DP4
DP5
DP6
DP7
AK-02
D-36
D-30
C-25
D-18
C-07
F-06
F-02
N-05
Pin Designations
NC
Vcc2
Vcc3
Vss
Pin
No.
Pin
No.
Pin
No.
Pin
No.
A-37
E-17
E-25
R-34
S-33
S-35
W-33
AJ-15
AJ-23
AL-19
AN-35
A-07
A-09
A-11
A-13
A-15
A-17
B-02
E-15
G-01
J-01
L-01
N-01
Q-01
S-01
U-01
W-01
Y-01
AA-01
AC-01
AE-01
AG-01
AJ-11
AN-09
AN-11
AN-13
AN-15
AN-17
AN-19
A-19
A-21
A-23
A-25
A-27
A-29
E-21
E-27
E-37
G-37
J-37
L-33
L-37
N-37
Q-37
S-37
T-34
U-33
U-37
W-37
Y-37
AA-37
AC-37
AE-37
AG-37
AJ-19
AJ-29
AN-21
AN-23
AN-25
AN-27
AN-29
INC
C-01
H-34
Y-35
Z-34
AC-35
AL-07
AN-01
AN-03
RSVD
J-33
L-35
P-04
Q-03
Q-35
R-04
S-03
S-05
AA-03
AC-03
AC-05
AD-04
AE-03
AE-35
KEY
AH-32
A-03
B-06
B-08
B-10
B-12
B-14
B-16
B-18
B-20
B-22
B-24
B-26
B-28
E-11
E-13
E-19
E-23
E-29
E-31
H-02
H-36
K-02
K-36
M-02
M-36
P-02
P-36
R-02
R-36
T-02
T-36
U-35
V-02
V-36
X-02
X-36
Z-02
Z-36
AB-02
AB-36
AD-02
AD-36
AF-02
AF-36
AH-02
AJ-07
AJ-09
AJ-13
AJ-17
AJ-21
AJ-25
AJ-27
AJ-31
AJ-37
AL-37
AM-08
AM-10
AM-12
AM-14
AM-16
AM-18
AM-20
AM-22
AM-24
AM-26
AM-28
AM-30
AN-37
317
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Pin Designations
Chapter 40
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
41
Package Specifications
The package specifications for the AMD-K6 processor remain
unchanged with the integration of 0.25-micron process
technology. For information about the package specifications of
the AMD-K6 processor Model 7, see Chapter 20, “Package
Specifications” on page 271.
Chapter 41
Package Specifications
319
Preliminary Information
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320
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Package Specifications
Chapter 41
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
42
Ordering Information
Standard AMD-K6® Processor Model 7 Products
AMD standard products are available in several operating ranges. The ordering part
number (OPN) is formed by a combination of the elements below.
AMD-K6 /300
A F R
Case Temperature
R = 0°C–70°C
Operating Voltage
F = 2.1 V–2.3 V (Core) / 3.135 V–3.6 V (I/O)
Package Type
A = 321-pin CPGA
Performance Rating
/300
/266
/233
/200
Family/Core
AMD-K6
Table 72. Valid Ordering Part Number Combinations
OPN
Package Type
AMD-K6/300AFR
321-pin CPGA
AMD-K6/266AFR
321-pin CPGA
AMD-K6/233AFR
321-pin CPGA
AMD-K6/200AFR
321-pin CPGA
Operating Voltage
2.1V–2.3V (Core)
3.135V–3.6V (I/O)
2.1V–2.3V (Core)
3.135V–3.6V (I/O)
2.1V–2.3V (Core)
3.135V–3.6V (I/O)
2.1V–2.3V (Core)
3.135V–3.6V (I/O)
Case Temperature
0°C–70°C
0°C–70°C
0°C–70°C
0°C–70°C
Notes:
This table lists configurations planned to be supported in volume for this device. Consult the local
AMD sales office to confirm availability of specific valid combinations and to check on
newly-released combinations.
Chapter 42
Ordering Information
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Chapter 42
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Index
Numerics
A[20:3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237–238
A[31:3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
A20M# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79, 194
A20M# Masking of Cache Accesses . . . . . . . . . . . . . . . . . . 187
Absolute Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233, 305
Acknowledge, Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Address
Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Parity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Parity Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Stack, Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Address Bus . . . . . . . . . . . 81–85, 94, 121, 142, 146, 148, 183
ADS# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81, 237–238
ADSC# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
AHOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82, 224
-initiated inquire hit to modified line. . . . . . . . . . . . . . . 146
-initiated inquire hit to shared or exclusive line . . . . . . 144
-initiated inquire miss . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Restriction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Airflow Consideration, Layout and . . . . . . . . . . . . . . . . . . . 262
Airflow Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Allocate, Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
AMD-K6 MMX Enhanced Processor . . . . . . . . . . . . . . . . 5, 277
block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
instructions supported . . . . . . . . . . . . . . . . . . . . . . . . 49, 283
microarchitecture overview . . . . . . . . . . . . . . . . . . . . . . . . . 7
Model 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 3, 275
Model 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 3, 275
AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
APCHK#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Application Note, I/O Model . . . . . . . . . . . . . . . . . . . . . . . . 239
Architecture, Internal . . . . . . . . . . . . . . . . . . . . . . . . . . . 7, 279
Block Diagram, AMD-K6 Processor . . . . . . . . . . . . . . . . . . . 10
BOFF# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87, 150
Locked Operation with . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Boundary Scan
Register (BSR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Test Access Port (TAP) . . . . . . . . . . . . . . . . . . . . . . 205, 299
BR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Branch
execution unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
history table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
prediction . . . . . . . . . . . . . . . . . . . . . . . 5–6, 9, 20, 277–278
prediction logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18–19
target cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
BRDY#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
BRDYC# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89, 167, 237
BREQ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
BSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Buffer Characteristics, I/O . . . . . . . . . . . . . . . . . . . . . 237, 309
Buffer Model, I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Built-In Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Burst Reads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Burst Reads, Pipelined . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Burst Ready . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Burst Ready Copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89, 167
Burst Writeback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Bus
address . . . . . . . . . . . . . 82–85, 94, 121, 142, 146, 148, 183
arbitration cycles, inquire and . . . . . . . . . . . . . . . . . . . . 136
backoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121, 289
cycles, special. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
data . . . . . . . . . . . . . . . . . . . . . . 82, 85, 88, 92–93, 108, 111
. . . . . . . . . . . . . . . . . . . . . . . . . .124–126, 142, 148, 152
enables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
hold request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
state machine diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Bus States
address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
data-NA# requested . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
idle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
pipeline address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
pipeline data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
BYPASS Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Bypass Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
B
C
Backoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Base Address, SMM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
BE[7:0]# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
BF[2:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86, 167, 227
BIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Bits, Predecode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 172
Cache. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
branch target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
coherency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
disabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
flush. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
0.25-micron process technology . . . . . . . . . . . . . . . . . 1, 3, 275
0.35-micron process technology . . . . . . . . . . . . . . . . . 1, 3, 275
321-Pin Staggered CPGA Package Specification. . . . . . . . 271
60-MHz Bus
clock switching characteristics . . . . . . . . . . . . . . . . . . . . 242
input setup and hold timings. . . . . . . . . . . . . . . . . . . . . . 250
output delay timings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
66-MHz Bus
clock switching characteristics . . . . . . . . . . . . . . . . . . . . 242
input setup and hold timings. . . . . . . . . . . . . . . . . . . . . . 246
output delay timings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
A
Index
323
Preliminary Information
AMD-K6® Processor Data Sheet
inhibit, L1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
MESI states in the data . . . . . . . . . . . . . . . . . . . . . . . . . . 172
operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171, 293
snooping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
writeback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10–11
CACHE# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90, 175
Cacheable Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Cacheable Page, Write to a . . . . . . . . . . . . . . . . . . . . . . . . . 178
Cache-Line
fills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177, 184
Cache-Related Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Capture-DR state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Capture-IR state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Case Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Centralized Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Characteristics
I/O buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237, 309
I/O Buffer AC and DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
CLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Clock Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223, 301
Clock States
halt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
stop clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161, 226–227
stop grant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161, 225
stop grant inquire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Coherency States, Writethrough vs. Writeback. . . . . . . . . 187
Coherency, Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
INVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
WBINVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Compatibility, Floating-Point and MMX instructions . . . . 191
Configuration and Initialization, Power-on . . . . . . . . 167, 291
Connection Requirements, Pin . . . . . . . . . . . . . . . . . . . . . . 231
Connections, Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . 229, 303
Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Control Unit, Scheduler/Instruction . . . . . . . . . . . . . . . . . . . . 9
Counter, Time Stamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Cycle, Hold and Hold Acknowledge . . . . . . . . . . . . . . . . . . 136
Cycle, Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Cycles
bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121, 289
inquire . . . . . . . 79–84, 94, 98–99, 112, 116, 132, 136, 138
. . . . . . . . . . . . . . . . .140, 142, 144–146, 148, 150, 154
. . . . . . . . . . . . . . . . . . . . . . . . . 183–187, 215, 223–226
inquire and bus arbitration . . . . . . . . . . . . . . . . . . . . . . . 136
interrupt acknowledge . . . . . . . . . . 80, 83, 85, 91, 106, 115
locked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
pipelined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 81
pipelined write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
special bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
writeback . . . . . . . . . . . . . . . . . .79, 81–82, 95, 98, 116, 132
. . . . . . . . . . . . . . . . . . . . . 140, 144, 146, 148, 150, 154
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174–175, 216, 226
D
D/C# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D[63:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
324
20695H/0—March 1998
Data Bus . . . . . . . . . . . . . . . . . . . . 82, 85, 88, 92–93, 108, 111
. . . . . . . . . . . . . . . . . . . . . . . . . .124–126, 142, 148, 152
Data Cache, MESI States in the . . . . . . . . . . . . . . . . . . . . . 172
Data Parity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Data Types
floating-point register . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
integer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Data/Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234, 306
Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Debug Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Debug Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34, 216
DR3–DR0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR5–DR4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
DR7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Decode, Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Decoders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Decoupling
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Descriptions, Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79, 287
Design, Thermal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259, 313
Designations, Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269, 317
Device Identification Register . . . . . . . . . . . . . . . . . . 210, 300
Diagram, Pin Description . . . . . . . . . . . . . . . . . . . . . . 267, 315
Diagrams, Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
DIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210, 300
Disabling, Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Dissipation, Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235, 307
DP[7:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
DR3–DR0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR5–DR4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
DR7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Drive Strength, Selectable . . . . . . . . . . . . . . . . . . . . . . . . . 237
E
EADS#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
EFER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
EFLAGS Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233, 305
Environment, Software . . . . . . . . . . . . . . . . . . . . . . . . . 21, 281
EWBE# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95, 224
Exception . . . . . 83–84, 93, 96, 108, 160, 191, 202, 220–222
flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26–27
floating-point . . . . . . . . . . . . . . . . . . . . . . . 96, 100, 189–191
machine check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Exception Handler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Exceptions
and interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
debug. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
floating-point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
handling floating-point . . . . . . . . . . . . . . . . . . . . . . . . . . 189
interrupts, and debug in SMM . . . . . . . . . . . . . . . . . . . . 202
MMX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Execution Unit, Branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Execution Unit, Multimedia . . . . . . . . . . . . . . . . . . . . . . . . 191
Execution Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
floating-point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189, 295
External Address Strobe . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
External Write Buffer Empty . . . . . . . . . . . . . . . . . . . . . . . . 95
EXTEST instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Index
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
F
FERR# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 191
Fetch, Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Float Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118, 288
Floating-Point
and MMX instruction compatibility . . . . . . . . . . . . . . . . 191
and multimedia execution units . . . . . . . . . . . . . . . 189, 295
error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
execution unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189, 295
registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Floating-Point
handling exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
register data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
FLUSH# . . . . . . . . . . . . . . . . . . . . . . . . . 97, 167, 184, 204, 224
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227, 242, 253
operating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86, 91, 167
Frequency Multiplier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
G
Gate Descriptor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45, 48
General-Purpose Registers . . . . . . . . . . . . . . . . . . . . . . 21, 281
Grounding, Power and . . . . . . . . . . . . . . . . . . . . . . . . . 229, 303
H
Halt State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Handling Floating-Point Exceptions . . . . . . . . . . . . . . . . . . 189
Heat Dissipation Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
HIGHZ instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
History Table, Branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Hit to modified line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Hit to Modified Line, AHOLD-Initiated Inquire . . . . . . . . 146
Hit to Modified Line, HOLD-Initiated Inquire . . . . . . . . . 140
Hit to Shared or Exclusive Line, AHOLD-Initiated
Inquire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Hit to Shared or Exclusive Line, HOLD-Initiated
Inquire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
HIT# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
HITM# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98, 237–238
HLDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
HOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Hold Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . .99, 136–138
Hold and Hold Acknowledge Cycle . . . . . . . . . . . . . . . . . . 136
Hold Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241, 255
HOLD-Initiated Inquire Hit to Modified Line . . . . . . . . . . 140
HOLD-Initiated Inquire Hit to Shared or Exclusive
Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
I
I/O
buffer characteristics . . . . . . . . . . . . . . . . . . . . . . . . 237, 309
buffer model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
misaligned read and write . . . . . . . . . . . . . . . . . . . . . . . . 135
model application note. . . . . . . . . . . . . . . . . . . . . . . . . . . 239
read and write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
trap dword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
trap restart slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
I/O Buffer AC and DC Characteristics . . . . . . . . . . . . . . . . 239
IBIS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
IDCODE instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Index
IEEE 1149.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 205, 277, 300
IEEE 754 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 25, 189, 277
IEEE 854 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 25, 189, 277
IGNNE#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100, 191
Ignore Numeric Exception . . . . . . . . . . . . . . . . . . . . . . . . . 100
INIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101, 224
INIT, State of Processor After . . . . . . . . . . . . . . . . . . . . . . 170
Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Initialization, Power-on Configuration and . . . . . . . . 167, 291
INIT-Initiated Transition from Protected Mode to
Real Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Input Setup and Hold Timings for 60-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Input Setup and Hold Timings for 66-MHz Bus
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Inquire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139, 141, 143, 223
cycles . . . . . . . . . . . . . . . . . . . . . 79–84, 94, 98–99, 112, 116
. . . . . . . . . . . . . 132, 136, 138, 140, 142, 144–146, 148
. . . . . . . . . . . . . . . . . 150, 154, 183–187, 215, 223–226
Inquire and Bus Arbitration Cycles . . . . . . . . . . . . . . . . . . 136
Inquire Cycle Hit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Inquire Cycle Hit To Modified Line . . . . . . . . . . . . . . . . . . . 98
Inquire Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Inquire Miss, AHOLD-Initiated . . . . . . . . . . . . . . . . . . . . . 142
Instruction Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Instruction Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Instruction Pointer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Instruction Prefetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Instructions Supported by the AMD-K6 Processor. . . 49, 283
Instructions, TAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Integer Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Internal Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7, 279
Internal Snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Interrupt . . . . . . . . . . . . . . . . . . . 102, 111, 156, 160–161, 164
. . . . . . . . . . . . . . . . . 170, 189–191, 194, 202, 221, 226
acknowledge cycles . . . . . . . . . . . . 80, 83, 85, 91, 106, 115
descriptor table register . . . . . . . . . . . . . . . . . . . . . . . 39–40
flag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102, 111
flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
redirection bitmap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
service routine . . . . . . . . . . . . . . . . . . . . . 102, 106, 190, 193
system management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Interrupt Acknowledge . . . . . . . . . . . . . . . . . . . 80, 88, 91, 102
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104, 108, 152, 156
Interrupt Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Interrupt, Type of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Interrupts
01h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
03h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
10h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
exceptions and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
INTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
IRQ13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
NMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
INTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102, 224
INV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Invalidation Request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
INVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
K
KEN# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
325
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
L
P
L1 Cache Inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Limit, Write Allocate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Line Fills, Cache- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
LOCK# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Locked Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Locked Operation with BOFF# Intervention . . . . . . . . . . . 154
Locked Operation, Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Logic
branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
branch-prediction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18–19
external support of floating-point exceptions . . . . . . . . 189
symbol diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77, 285
Package Specifications . . . . . . . . . . . . . . . . . . . . . . . . 271, 319
Package Thermal Specifications . . . . . . . . . . . . . . . . 259 , 313
Page Cache Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Page Directory Entry (PDE) . . . . . . . . . . . . . . . . . . 43–44, 174
Page Table Entry (PTE). . . . . . . . . . . . . . . . . . . . . . 43, 45, 174
Page Writethrough. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Paging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Parity. . . . . . . . . . . . . . . . . . . . . . 77, 83, 85, 93, 108, 126, 285
bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83, 93, 108
check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83–84, 93
error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84, 108, 142, 206
flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Parity Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Part number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273, 321
PCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107, 174, 180
PCHK# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Pin Connection Requirements . . . . . . . . . . . . . . . . . . . . . . 231
Pin Description Diagram. . . . . . . . . . . . . . . . . . . . . . . 267, 315
Pin Designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269, 317
Pipeline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 124–125, 130
Pipeline Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Pipeline, Six-stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8–9
Pipelined. . . . . . . . . . . . 11, 106, 125, 130–131, 148, 171, 182
Pipelined Burst Reads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Pipelined Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 81, 92
Pipelined Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Pointer, Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . 229, 303
Power Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . 229, 303
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235, 307
Power-on Configuration and Initialization . . . . . . . . 167 , 291
Predecode Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11–12, 172
Prefetching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 181
PWT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
M
M/IO# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Machine Check Exception . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Maskable Interrupt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
MCAR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37, 170
MCTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37–38, 170
Memory or I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Memory Read and Write, Misaligned Single-Transfer . . . 128
Memory Read and Write, Single-Transfer . . . . . . . . . . . . . 126
Memory Reads and Writes. . . . . . . . . . . . . . . . . . . . . . . . . . 126
MESI. . . . . . . . . . . . . 5, 11, 136, 140, 172, 182, 185, 187, 277
bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12, 172–173
states in the data cache . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Microarchitecture Overview, AMD-K6 Processor . . . . . . . . . 7
Microarchitecture, Enhanced RISC86 . . . . . . . . . . . . . . . . . . 8
Misaligned I/O Read and Write. . . . . . . . . . . . . . . . . . . . . . 135
Misaligned Single-Transfer Memory Read and Write. . . . 128
MMX
exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
instruction compatibility, floating-point and . . . . . . . . . 191
registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Mode, Tri-State Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 299
Model 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 3, 275
Model 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 3, 275
Model-specific registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
MSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37, 281
Multimedia Execution Unit . . . . . . . . . . . . . . . . . . . . . . . . . 191
N
NA#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Next Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
NMI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106, 224
No-connect Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110, 231
Non-Maskable Interrupt. . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Non-Pipelined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127, 176
O
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233, 305
Operation, Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
OPN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273, 321
Ordering Part Number . . . . . . . . . . . . . . . . . . . . . . . . . 273, 321
Organization, Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . 171, 293
Output Delay Timings for 60-MHz Bus Operation . . . . . . . 248
Output Delay Timings for 66-MHz Bus Operation . . . . . . . 244
Output Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168, 291
326
R
Ranges, Operating . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233, 305
Ratings, Absolute. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233, 305
Read and Write, Basic I/O. . . . . . . . . . . . . . . . . . . . . . . . . . 134
Read and Write, Misaligned I/O . . . . . . . . . . . . . . . . . . . . . 135
Reads, Burst Reads and Pipelined Burst. . . . . . . . . . . . . . 130
Register
boundary scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
bypass (BR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
data Types, floating-point . . . . . . . . . . . . . . . . . . . . . . . . . 28
debug. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34, 216
floating-point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
general-purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21, 281
SYSCALL/SYSRET Target Address (STAR) . . . . . . . . . 282
Registers . . . . . . . . . . . . . . . . . . . . . . 9, 21, 168, 191, 281, 291
descriptors and gates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
device identification (DIR) . . . . . . . . . . . . . . . . . . . 210, 300
DR3–DR0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR5–DR4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
DR6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
DR7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
EFLAGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
extended feature enable register (EFER). . . . . . . . . . . 282
Index
Preliminary Information
20695H/0—March 1998
IR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
MCAR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
memory management . . . . . . . . . . . . . . . . . . . . . . . . . 39, 283
MMX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
STAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
TAP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206, 300
TR12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
WHCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39, 283
Regulator, Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Replacement, Cache-Line . . . . . . . . . . . . . . . . . . . . . . 177, 184
Requirements, Pin Connection . . . . . . . . . . . . . . . . . . . . . . 231
Reserved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110, 168, 224
and Test Signal Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . 252
signals sampled during. . . . . . . . . . . . . . . . . . . . . . . . . . . 167
state of processor after. . . . . . . . . . . . . . . . . . . . . . . 168, 291
Return Address Stack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Revision Identifier, SMM . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
RISC86 Microarchitecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
RSM Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199, 202
RSVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
S
SAMPLE/PRELOAD instruction . . . . . . . . . . . . . . . . . . . . . 212
Scheduler, Centralized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Scheduler/Instruction Control Unit . . . . . . . . . . . . . . . . . . . . 9
SCYC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Sector, Write to a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Segment Descriptor . . . . . . . . . . . . . . . . . . . . . . . . . .24, 45–47
Segment Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Segment Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Segment, Task State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Selectable Drive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Shift-DR state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Shift-IR state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Shutdown Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Signal Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79, 287
Signal Switching Characteristics. . . . . . . . . . . . . . . . . 241, 311
Signal Timing, RESET and Test . . . . . . . . . . . . . . . . . . . . . 252
Signals
A[20:3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237–238
A[31:3] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
A20M# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79, 194
ADS# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81, 237–238
ADSC# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
AHOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82, 224
AP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
APCHK#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
BE[7:0]# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
BF[2:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86, 227
BOFF# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87, 150
BRDY# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
BRDYC# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89, 237
BREQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
CACHE#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90, 175
CLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D/C# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D[63:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
DP[7:0] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
EADS# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
EWBE# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95, 224
FERR# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96, 191
Index
AMD-K6® Processor Data Sheet
FLUSH# . . . . . . . . . . . . . . . . . . . . . . 97, 167, 184, 204, 224
HIT# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
HITM# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98, 237–238
HLDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
HOLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
IGNNE#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100, 191
INIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101, 224
INTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102, 224
INV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
KEN# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
LOCK#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
M/IO#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
NA# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
NMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106, 224
PCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
PCHK# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
PWT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
RESET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110, 224
RSVD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
SCYC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
SMI# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111, 193, 224
SMIACT#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112, 193
STPCLK# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113, 225
TCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
TDI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TDO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TRST# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
VCC2DET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115, 287
VCC2H/L#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
W/R# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115, 237–238
WB/WT# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Signals Sampled During RESET . . . . . . . . . . . . . . . . . . . . 167
Signals, Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168, 291
Signals, TAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Single-Transfer Memory Read and Write . . . . . . . . . . . . . 126
SMI# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111, 193, 224
SMIACT#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112, 193
SMM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193, 297
base address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
default register values. . . . . . . . . . . . . . . . . . . . . . . . . . . 193
halt restart slot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
I/O trap DWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
I/O trap restart slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
operating mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
revision identifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
state-save area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Snoop. . . . . . . . . . . . . . . . . . . . . . 112, 116, 132, 183, 185–186
Snooping, Cache. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Snooping, Internal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Software Environment. . . . . . . . . . . . . . . . . . . . . . . . . . 21, 281
Special Bus Cycle. . . . . . . . . . . . . 88, 113, 158–161, 200, 225
Special Bus Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Special Cycle . . . . . . . . . . . . . . . . . 95, 97, 113, 119, 132, 158
. . . . . . . . . . . . . . . . . . . . . . . . . . 160–161, 176, 224–225
Specifications, Package. . . . . . . . . . . . . . . . . . . . . . . . 271, 319
Specifications, Package Thermal . . . . . . . . . . . . . . . . 259, 313
Split Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Stack, Return Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
State Machine Diagram, Bus. . . . . . . . . . . . . . . . . . . . . . . . 123
State of Processor After INIT . . . . . . . . . . . . . . . . . . . 170, 291
State of Processor After RESET . . . . . . . . . . . . . . . . 168, 291
States, Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
State-Save Area, SMM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
327
Preliminary Information
AMD-K6® Processor Data Sheet
20695H/0—March 1998
Stop Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Stop Clock State . . . . . . . . . . . . . . . . . . . . . . . . . .161, 226–227
Stop Grant Inquire State . . . . . . . . . . . . . . . . . . . . . . . 223–226
Stop Grant State . . . . . . . . . . . . . . . . . . . . . . . . . .161, 225–226
STPCLK# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113, 225
Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 241
60-MHz bus operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
66-MHz bus operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
input setup and hold timings for 60-MHz bus . . . . . . . . 250
input setup and hold timings for 66-MHz bus . . . . . . . . 246
output delay timings for 60-MHz bus . . . . . . . . . . . . . . . 248
output delay timings for 66-MHz bus . . . . . . . . . . . . . . . 244
Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241, 311
valid delay, float, setup, and hold timings . . . . . . . . . . . 243
SYSCALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282–283
SYSCALL/SYSRET Target Address Register
(STAR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282–283
SYSRET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
System Design, Airflow Management in a . . . . . . . . . . . . . 264
System Management Interrupt . . . . . . . . . . . . . . . . . . . . . . 111
System Management Interrupt Active . . . . . . . . . . . . . . . . 112
System Management Mode (SMM) . . . . . . . . . . . . . . . 193, 297
Test-Logic-Reset state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Thermal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235, 260–264, 307
design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259, 313
heat dissipation path . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
layout and airflow consideration . . . . . . . . . . . . . . . . . . 262
measuring case temperature . . . . . . . . . . . . . . . . . . . . . 262
package specifications . . . . . . . . . . . . . . . . . . . . . . 259, 313
Time Stamp Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Timing Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
TMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TR12 . . . . . . . . . . . . . . . . . . . . 37–38, 170, 174–175, 180, 215
Transition from Protected Mode to Real Mode,
INIT-Initiated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Translation Lookaside Buffer (TLB) . . . . . . . . . . . . . . . . . 171
Trap Dword, I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Tri-State Test Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 299
TRST# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
TSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37–38, 170, 224–225
TSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41, 47–48, 197, 220
T
VCC2DET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115, 287
VCC2H/L#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Voltage . . . . . . . . . . . . . . . . 115, 122, 229, 233–234, 238, 241
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287, 303, 305–306
regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262–263
Voltage Ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Table, Branch History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
TAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205, 299
TAP Controller States
Capture-DR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Capture-IR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Shift-DR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Shift-IR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
State Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
test-logic-reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Update-DR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Update-IR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
TAP Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
BYPASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
EXTEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
HIGHZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
IDCODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
SAMPLE/PRELOAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
TAP Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206, 300
Instruction Register (IR) . . . . . . . . . . . . . . . . . . . . . . . . . 206
TAP Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Target Cache, Branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Task State Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
TCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
TDI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
TDO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Temperature . . . . . . . . . . . . . . . . 233, 259–260, 262, 305, 313
case. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Test Access Port, Boundary-Scan. . . . . . . . . . . . . . . . . 205, 299
Test and Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203, 299
Test Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Test Data Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Test Data Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Test Mode Select. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Test Mode, Tri-State . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 299
Test Register 12 (TR12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Test Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
328
V
W
W/R# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115, 237–238
WAE15M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
WAELIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
WB/WT# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
WBINVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
WCDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39, 178, 181
WHCR . . . . . . . . . . . . . . . . . . . . . . . 37, 39, 170, 179, 181, 283
Write Allocate . . . . . . . . . . . . . . . . . . . . . . . . . . . 173, 177–182
enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39, 178
enable limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39, 178
limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
logic mechanisms and conditions . . . . . . . . . . . . . . . . . . 180
Write Handling Control Register (WHCR) . . . . . . . . . 39, 283
Write to a Cacheable Page . . . . . . . . . . . . . . . . . . . . . . . . . 178
Write to a Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Write/Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Writeback . . . . . . . . . . . . . 90, 92–93, 103, 109, 112, 116, 119
. . . . . . . . .132–133, 158, 171, 176, 182, 185, 187, 228
burst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
cycles . . . . . . . . . . . . . . . . . . . . . 79, 81–82, 95, 98, 116, 132
. . . . . . . . . . . . . . . . . . . . . 140, 144, 146, 148, 150, 154
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174–175, 216, 226
Writeback Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10–11
Writeback or Writethrough . . . . . . . . . . . . . . . . . . . . . . . . 116
Writethrough vs. Writeback Coherency States. . . . . . . . . 187
Index