INTEL 82434NX

82434LX/82434NX PCI, CACHE AND MEMORY
CONTROLLER (PCMC)
Y
Supports the Pentium TM Processor at
iCOMP TM Index 510T60 MHz and iCOMP
Index 567T66 MHz
Y
Supports the Pentium Processor at
iCOMP Index 735T90 MHz, iCOMP Index
815T100 MHz, and iCOMP Index 610T75
MHz
Y
Supports Pipelined Addressing
Capability of the Pentium Processor
Y
The 82430NX Drives 3.3V Signal Levels
on the CPU and Cache Interfaces
Y
High Performance CPU/PCI/Memory
Interfaces via Posted Write and Read
Prefetch Buffers
Y
Fully Synchronous PCI Interface with
Full Bus Master Capability
Y
Supports the Pentium Processor
Internal Cache in Either Write-Through
or Write-Back Mode
Y
Programmable Attribute Map of DOS
and BIOS Regions for System
Flexibility
Y
Integrated Low Skew Clock Driver for
Distributing Host Clock
Y
Integrated Second Level Cache
Controller
Ð Integrated Cache Tag RAM
Ð Write-Through and Write-Back Cache
Modes for the 82434LX
Ð Write-Back for the 82434NX
Ð 82434NX Supports Low-Power Cache
Standby
Ð Direct Mapped Organization
Ð Supports Standard and Burst SRAMs
Ð 256-KByte and 512-KByte Sizes
Ð Cache Hit Cycle of 3-1-1-1 on Reads
and Writes Using Burst SRAMs
Ð Cache Hit Cycle of 3-2-2-2 on Reads
and 4-2-2-2 on Writes Using
Standard SRAMs
Y
Integrated DRAM Controller
Ð Supports 2 MBytes to 192 MBytes of
Cacheable Main Memory for the
82434LX
Ð Supports 2 MBytes to 512 MBytes of
Cacheable Main Memory for the
82434NX
Ð Supports DRAM Access Times of
70 ns and 60 ns
Ð CPU Writes Posted to DRAM 4-1-1-1
Ð Refresh Cycles Decoupled from ISA
Refresh to Reduce the DRAM
Access Latency
Ð Six RASÝ Lines (82434LX)
Ð Eight RASÝ Lines (82434NX)
Ð Refresh by RASÝ-Only, or CASBefore-RASÝ, in Single or Burst
of Four
Y
Host/PCI Bridge
Ð Translates CPU Cycles into PCI Bus
Cycles
Ð Translates Back-to-Back Sequential
CPU Memory Writes into PCI Burst
Cycles
Ð Burst Mode Writes to PCI in Zero PCI
Wait-States (i.e. Data Transfer Every
Cycle)
Ð Full Concurrency Between CPU-toMain Memory and PCI-to-PCI
Transactions
Ð Full Concurrency Between CPU-toSecond Level Cache and PCI-to-Main
Memory Transactions
Ð Same Cache and Memory System
Logic Design for ISA and EISA
Systems
Ð Cache Snoop Filter Ensures Data
Consistency for PCI-to-Main Memory
Transactions
Y
208-Pin QFP Package
*Other brands and names are the property of their respective owners.
December 1994
Order Number: 290479-004
82434LX/82434NX
This document describes both the 82434LX and 82434NX. Unshaded areas describe the 82434LX.
Shaded areas, like this one, describe 82434NX operations that differ from the 82434LX.
The 82434LX/82434NX PCI, Cache, Memory Controllers (PCMC) integrate the cache and main memory
DRAM control functions and provide bus control for transfers between the CPU, cache, main memory, and the
PCI Local Bus. The cache controller supports write-back (or write-through for 82434LX) cache policy and
cache sizes of 256-KBytes and 512-KBytes. The cache memory can be implemented with either standard or
burst SRAMs. The PCMC cache controller integrates a high-performance Tag RAM to reduce system cost.
2
82434LX/82434NX
290479 – 1
NOTE:
RAS[7:6] Ý and MA11 are only on the 82434NX. CCS[1:0] functionality is only on the 82434NX.
Simplified Block Diagram of the PCMC
3
82434LX/82434NX PCI, CACHE AND MEMORY
CONTROLLER (PCMC)
CONTENTS
PAGE
1.0 ARCHITECTURAL OVERVIEW ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 10
1.1 System Overview ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 10
1.1.1 BUS HIERARCHYÐCONCURRENT OPERATIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 10
1.1.2 BUS BRIDGES ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 13
1.2 PCMC Overview ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 13
1.2.1 CACHE OPERATIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 14
1.2.1.1 Cache Consistency ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 15
1.2.2 ADDRESS/DATA PATHS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 15
1.2.2.1 Read/Write Buffers ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 15
1.2.3 HOST/PCI BRIDGE OPERATIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 15
1.2.4 DRAM MEMORY OPERATIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 16
1.2.5 3.3V SIGNALS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 16
2.0 SIGNAL DESCRIPTIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 16
2.1 Host Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 17
2.2 DRAM Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 22
2.3 Cache Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 23
2.4 PCI Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 24
2.5 LBX Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 28
2.6 Reset And Clock ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 28
3.0 REGISTER DESCRIPTION ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 30
3.1 I/O Mapped Registers ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 31
3.1.1 CONFADDÐCONFIGURATION ADDRESS REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 31
3.1.2 CSEÐCONFIGURATION SPACE ENABLE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 32
3.1.3 TRCÐTURBO-RESET CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 33
3.1.4 FORWÐFORWARD REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 34
3.1.5 PMCÐPCI MECHANISM CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 34
3.1.6 CONFDATAÐCONFIGURATION DATA REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 34
3.2 PCI Configuration Space Mapped Registers ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 35
3.2.1 CONFIGURATION SPACE ACCESS MECHANISM ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 36
3.2.1.1 Access Mechanism Ý1: ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 36
3.2.1.2 Access Mechanism Ý2 ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 37
3.2.2 VIDÐVENDOR IDENTIFICATION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 40
3.2.3 DIDÐDEVICE IDENTIFICATION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 40
4
CONTENTS
PAGE
3.2.4 PCICMDÐPCI COMMAND REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 41
3.2.5 PCISTSÐPCI STATUS REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 42
3.2.6 RIDÐREVISION IDENTIFICATION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 43
3.2.7 RLPIÐREGISTER-LEVEL PROGRAMMING INTERFACE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀ 43
3.2.8 SUBCÐSUB-CLASS CODE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 43
3.2.9 BASECÐBASE CLASS CODE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 44
3.2.10 MLTÐMASTER LATENCY TIMER REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 44
3.2.11 BISTÐBIST REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 44
3.2.12 HCSÐHOST CPU SELECTION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 45
3.2.13 DFCÐDETURBO FREQUENCY CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 46
3.2.14 SCCÐSECONDARY CACHE CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 46
3.2.15 HBCÐHOST READ/WRITE BUFFER CONTROL ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 48
3.2.16 PBCÐPCI READ/WRITE BUFFER CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 49
3.2.17 DRAMCÐDRAM CONTROL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 50
3.2.18 DRAMTÐDRAM TIMING REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 51
3.2.19 PAMÐPROGRAMMABLE ATTRIBUTE MAP REGISTERS (PAM [6:0] ) ÀÀÀÀÀÀÀÀÀÀÀ 51
3.2.20 DRBÐDRAM ROW BOUNDARY REGISTERS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 54
3.2.20.1 82434LX Description ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 54
3.2.20.2 82434NX Description ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 56
3.2.21 DRBEÐDRAM ROW BOUNDARY EXTENSION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 58
3.2.22 ERRCMDÐERROR COMMAND REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 58
3.2.23 ERRSTSÐERROR STATUS REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 60
3.2.24 SMRSÐSMRAM SPACE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 61
3.2.25 MSGÐMEMORY SPACE GAP REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 61
3.2.26 FBRÐFRAME BUFFER RANGE REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 62
4.0 PCMC ADDRESS MAP ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 64
4.1 CPU Memory Address Map ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 64
4.2 System Management RAMÐSMRAM ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 64
4.3 PC Compatibility Range ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 65
4.4 I/O Address Map ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 66
5
CONTENTS
PAGE
5.0 SECOND LEVEL CACHE INTERFACE ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 67
5.1 82434LX Cache ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 67
5.1.1 CLOCK LATENCIES (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 75
5.1.2 STANDARD SRAM CACHE CYCLES (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 76
5.1.2.1 Burst Read (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 76
5.1.2.2 Burst Write (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 78
5.1.2.3 Cache Line Fill (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 80
5.1.3 BURST SRAM CACHE CYCLES (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 84
5.1.3.1 Burst Read (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 84
5.1.3.2 Burst Write (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 86
5.1.3.3 Cache Line Fill (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 88
5.1.4 SNOOP CYCLES ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 90
5.1.5 FLUSH, FLUSH ACKNOWLEDGE AND WRITE-BACK SPECIAL CYCLES ÀÀÀÀÀÀÀÀÀ 98
5.2 82434NX Cache ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 98
5.2.1 CYCLE LATENCY SUMMARY (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 102
5.2.2 STANDARD SRAM CACHE CYCLES (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 103
5.2.3 SECOND LEVEL CACHE STANDBY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 103
5.2.4 SNOOP CYCLES ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 103
5.2.5 FLUSH, FLUSH ACKNOWLEDGE, AND WRITE-BACK SPECIAL CYCLES ÀÀÀÀÀÀÀÀ 103
6.0 DRAM INTERFACE ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 104
6.1 82434LX DRAM Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 104
6.1.1 DRAM CONFIGURATIONS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 105
6.1.2 DRAM ADDRESS TRANSLATION ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 105
6.1.3 CYCLE TIMING SUMMARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 108
6.1.4 CPU TO DRAM BUS CYCLES ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 108
6.1.4.1 Read Page Hit ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 108
6.1.4.2 Read Page Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 110
6.1.4.3 Read Row Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 111
6.1.4.4 Write Page Hit ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 112
6.1.4.5 Write Page Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 113
6.1.4.6 Write Row Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 114
6.1.4.7 Read Cycle, 0-Active RASÝ Mode ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 115
6.1.4.8 Write Cycle, 0-Active RASÝ Mode ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 116
6
CONTENTS
PAGE
6.1.5 REFRESH ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 117
6.1.5.1 RASÝ-Only Refresh-Single ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 117
6.1.5.2 CASÝ-Before-RASÝ Refresh-Single ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 119
6.1.5.3 Hidden Refresh-Single ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 120
6.2 82434NX DRAM Interface ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 121
6.2.1 DRAM ADDRESS TRANSLATION ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 121
6.2.2 CYCLE TIMING SUMMARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 122
6.2.3 CPU TO DRAM BUS CYCLES ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 122
6.2.3.1 Burst DRAM Read Page Hit ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 123
6.2.3.2 Burst DRAM Read Page Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 124
6.2.3.3 Burst DRAM Read Row Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 125
6.2.3.4 Burst DRAM Write Page Hit ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 126
6.2.3.5 Burst DRAM Write Page Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 127
6.2.3.6 Burst DRAM Write Row Miss ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 128
6.2.4 REFRESH ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 129
6.2.4.1 RASÝ-Only RefreshÐSingle ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 129
6.2.4.2 CASÝ-before-RASÝ RefreshÐSingle ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 130
6.2.4.3 Hidden Refresh-Single ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 131
7.0 PCI INTERFACE ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 132
7.1 PCI Interface Overview ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 132
7.2 CPU-to-PCI Cycles ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 132
7.2.1 CPU WRITE TO PCI ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 132
7.3 Register Access Cycles ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 133
7.3.1 CPU WRITE CYCLE TO PCMC INTERNAL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 134
7.3.2 CPU READ FROM PCMC INTERNAL REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 135
7.3.3 CPU WRITE TO PCI DEVICE CONFIGURATION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 136
7.3.4 CPU READ FROM PCI DEVICE CONFIGURATION REGISTER ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 138
7.4 PCI-to-Main Memory Cycles ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 141
7.4.1 PCI MASTER WRITE TO MAIN MEMORY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 141
7.4.2 PCI MASTER READ FROM MAIN MEMORY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 143
7
CONTENTS
PAGE
8.0 SYSTEM CLOCKING AND RESET ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 144
8.1 Clock Domains ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 144
8.2 Clock Generation and Distribution ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 144
8.3 Phase Locked Loop Circuitry ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 145
8.4 System Reset ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 147
8.5 82434NX Reset Sequencing ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 149
9.0 ELECTRICAL CHARACTERISTICS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 150
9.1 Absolute Maximum Ratings ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 150
9.2 Thermal Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 150
9.3 82434LX DC Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 150
9.4 82434NX DC Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 152
9.5 82434LX AC Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 154
9.5.1 HOST CLOCK TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 154
9.5.2 CPU INTERFACE TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 155
9.5.3 SECOND LEVEL CACHE STANDARD SRAM TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀ 157
9.5.4 SECOND LEVEL CACHE BURST SRAM TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀ 158
9.5.5 DRAM INTERFACE TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 158
9.5.6 PCI CLOCK TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 158
9.5.7 PCI INTERFACE TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 159
9.5.8 LBX INTERFACE TIMING, 66 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 160
9.5.9 HOST CLOCK TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 160
9.5.10 CPU INTERFACE TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 161
9.5.11 SECOND LEVEL CACHE STANDARD SRAM TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀ 163
9.5.12 SECOND LEVEL CACHE BURST SRAM TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀ 164
9.5.13 DRAM INTERFACE TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 164
9.5.14 PCI CLOCK TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 165
9.5.15 PCI INTERFACE TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 165
9.5.16 LBX INTERFACE TIMING, 60 MHz (82434LX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 166
8
CONTENTS
PAGE
9.6 82434NX AC Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 167
9.6.1 HOST CLOCK TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 167
9.6.2 CPU INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 168
9.6.3 SECOND LEVEL CACHE STANDARD SRAM TIMING, 66 MHz (82434NX),
PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 170
9.6.4 SECOND LEVEL CACHE BURST SRAM TIMING, 66 MHz (82434NX),
PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 171
9.6.5 DRAM INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 171
9.6.6 PCI CLOCK TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 172
9.6.7 PCI INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 172
9.6.8 LBX INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 173
9.6.9 HOST CLOCK TIMING, 50 and 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 173
9.6.10 CPU INTERFACE TIMING, 50 AND 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 174
9.6.11 SECOND LEVEL CACHE STANDARD SRAM TIMING, 50 AND 60 MHz
(82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 176
9.6.12 SECOND LEVEL CACHE BURST SRAM TIMING, 50 AND 60 MHz
(82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 177
9.6.13 DRAM INTERFACE TIMING, 50 AND 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 177
9.6.14 PCI CLOCK TIMING, 50 AND 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 178
9.6.15 PCI INTERFACE TIMING, 50 AND 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 178
9.6.16 LBX INTERFACE TIMING, 50 AND 60 MHz (82434NX) ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 179
9.6.17 TIMING DIAGRAMS ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 179
10.0 PINOUT AND PACKAGE INFORMATION ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 182
10.1 Pin Assignment ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 182
10.2 Package Characteristics ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 189
11.0 TESTABILITY ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ 190
9
82434LX/82434NX
1.0 ARCHITECTURAL OVERVIEW
This section provides an 82430LX/82430NX PCIset
system overview that includes a description of the
bus hierarchy and bridges between the buses. The
82430LX PCIset consists of the 82434LX PCMC and
82433LX LBX components plus either a PCI/ISA
bridge or a PCI/EISA bridge. The 82430NX PCIset
consists of the 82434NX PCMC and 82433NX LBX
components plus either a PCI/ISA bridge or a PCI/
EISA bridge. The PCMC and LBX provide the core
cache and main memory architecture and serve as
the Host/PCI bridge. An overview of the PCMC follows the system overview section.
1.1 System Overview
The 82430LX/82430NX PCIset provides the Host/
PCI bridge, cache and main memory controller, and
an I/O subsystem core (either PCI/EISA or PCI/ISA
bridge) for the next generation of high-performance
personal computers based on the Pentium processor. System designers can take advantage of the
power of the PCI (Peripheral Component Interconnect) local bus while maintaining access to the large
base of EISA and ISA expansion cards. Extensive
buffering and buffer management within the bridges
ensures maximum efficiency in all three buses (Host
CPU, PCI, and EISA/ISA Buses).
For an ISA-based system, the PCIset includes the
System I/O (82378IB SIO) component (Figure 1) as
the PCI/ISA bridge. For an EISA-based system (Figure 2), the PCIset includes the PCI-EISA bridge
(82375EB PCEB) and the EISA System Component
(82374EB ESC). The PCEB and ESC work in tandem to form the complete PCI/EISA bridge.
1.1.1. BUS HIERARCHYÐCONCURRENT
OPERATIONS
Systems based on the 82430LX/82430NX PCIset
contain three levels of buses structured in the following hierarchy:
10
# Host Bus as the execution bus
# PCI Bus as a primary I/O bus
# ISA or EISA Bus as a secondary I/O bus.
This bus hierarchy allows concurrency for simultaneous operations on all three buses. Data buffering
permits concurrency for operations that crossover
into another bus. For example, the Pentium processor could post data destined to the PCI in the LBX.
This permits the Host transaction to complete in
minimum time, freeing up the Host Bus for further
transactions. The Pentium processor does not have
to wait for the transfer to complete to its final destination. Meanwhile, any ongoing PCI Bus transactions are permitted to complete. The posted data is
then transferred to the PCI Bus when the PCI Bus is
available. The LBX implements extensive buffering
for Host-to-PCI, Host-to-main memory, and PCI-tomain memory transactions. In addition, the PCEB/
ESC chip set and the SIO implement extensive buffering for transfers between the PCI Bus and the
EISA and ISA Buses, respectively.
Host Bus
Designed to meet the needs of high-performance
computing, the Host Bus features:
#
#
#
#
64-bit data path
32-bit address bus with address pipelining
Synchronous frequencies of 60 MHz and 66 MHz
Synchronous frequency of 50 MHz (82430NX)
# Burst read and write transfers
# Support for first level and second level caches
# Capable of full concurrency with the PCI and
memory subsystems
# Byte data parity
# Full support for Pentium processor machine
check and DOS compatible parity reporting
# Support for Pentium processor System Management Mode (SMM).
82434LX/82434NX
290479 – 2
Figure 1. Block Diagram of a 82430LX/82430NX PCIset ISA System
PCI Bus
The PCI Bus is designed to address the growing industry needs for a standardized local bus that is not
directly dependent on the speed and the size of the
processor bus. New generations of personal computer system software such as Windows TM and
Win-NT TM with sophisticated graphical interfaces,
multi-tasking, and multi-threading bring new requirements that traditional PC I/O architectures cannot
satisfy. In addition to the higher bandwidth, reliability
and robustness of the I/O subsystem are becoming
increasingly important. PCI addresses these needs
and provides a future upgrade path. PCI features include:
# Processor independent
# Multiplexed, burst mode operation
# Synchronous at frequencies up to 33 MHz
# 120 MByte/sec usable throughput
(132 MByte/sec peak) for a 32-bit data path
11
82434LX/82434NX
# Low latency random access (60 ns write access
latency to slave registers from a master parked
on the bus)
# Capable of full concurrency with the processor/
memory subsystem
# Full multi-master capability allowing any PCI master peer-to-peer access to any PCI slave
# Hidden (overlapped) central arbitration
# Low pin count for cost effective component packaging (multiplexed address/data)
# Address and data parity
# Three physical address spaces: memory, I/O,
and configuration
# Comprehensive support for autoconfiguration
through a defined set of standard configuration
functions.
290479 – 3
Figure 2. Block Diagram of the 82430LX/82430NX PCIset EISA System
12
82434LX/82434NX
ISA Bus
Figure 1 represents a system using the ISA Bus as
the second level I/O bus. It allows personal computer platforms built around the PCI as a primary I/O
bus to leverage the large ISA product base. The ISA
Bus has 24-bit addressing and a 16-bit data path.
EISA Bus
Figure 2 represents a system using the EISA Bus as
the second level I/O bus. It allows personal computer platforms built around the PCI as a primary I/O
bus to leverage the large EISA/ISA product base.
Combinations of PCI and EISA buses, both of which
can be used to provide expansion functions, will satisfy even the most demanding applications.
Along with compatibility for 16-bit and 8-bit ISA hardware and software, the EISA bus provides the following key features:
# 32-bit addressing and 32-bit data path
# 33 MByte/sec bus bandwidth
# Multiple bus master support through efficient arbitration
# Support for autoconfiguration.
ance by maximizing PCI and EISA Bus efficiency and
allowing concurrency on the two buses. The PCEB’s
buffer management mechanism ensures data coherency. The PCEB integrates central bus control functions including a programmable bus arbiter for the
PCI Bus and EISA data swap buffers for the EISA
Bus. Integrated system functions include PCI parity
generation, system error reporting, and programmable PCI and EISA memory and I/O address space
mapping and decoding. The PCEB also contains a
BIOS Timer that can be used to implement timing
loops. The PCEB is intended to be used with the
ESC to provide an EISA I/O subsystem interface.
The ESC integrates the common I/O functions
found in today’s EISA-based PCs. The ESC incorporates the logic for EISA Bus controller, enhanced
seven channel DMA controller with scatter-gather
support, EISA arbitration, 14 level interrupt controller, Advanced Programmable Interrupt Controller
(APIC), five programmable timer/counters, nonmaskable-interrupt (NMI) control, and power management. The ESC also integrates support logic to
decode peripheral devices (e.g., the flash BIOS, real
time clock, keyboard/mouse controller, floppy controller, two serial ports, one parallel port, and IDE
hard disk drive).
PCI/ISA Bridge (SIO):
1.1.2 BUS BRIDGES
Host/PCI Bridge Chip Set (PCMC and LBX)
The PCMC and LBX enhance the system performance by allowing for concurrency between the Host
CPU Bus and PCI Bus, giving each greater bus
throughput and decreased bus latency. The LBX
contains posted write buffers for Host-to-PCI, Hostto-main memory, and PCI-to-main memory transfers.
The LBX also contains read prefetch buffers for
Host reads of PCI, and PCI reads of main memory.
There are two LBXs per system. The LBXs are controlled by commands from the PCMC. The PCMC/
LBX Host/PCI bridge chip set is covered in more
detail in Section 1.2, PCMC Overview.
PCI-EISA Bridge Chip Set (PCEB and ESC)
The PCEB provides the master/slave functions on
both the PCI Bus and the EISA Bus. Functioning as
a bridge between the PCI and EISA buses, the
PCEB provides the address and data paths, bus
controls, and bus protocol translation for PCI-toEISA and EISA-to-PCI transfers. Extensive data buffering in both directions increase system perform-
The SIO component provides the bridge between
the PCI Bus and the ISA Bus. The SIO also integrates many of the common I/O functions found in
today’s ISA-based PCs. The SIO incorporates the
logic for a PCI interface (master and slave), ISA interface (master and slave), enhanced seven channel
DMA controller that supports fast DMA transfers and
scatter-gather, data buffers to isolate the PCI Bus
from the ISA Bus and to enhance performance, PCI
and ISA arbitration, 14 level interrupt controller, a
16-bit BIOS timer, three programmable timer/counters, and non-maskable-interrupt (NMI) control logic.
The SIO also provides decode for peripheral devices
(e.g., the flash BIOS, real time clock, keyboard/
mouse controller, floppy controller, two serial ports,
one parallel port, and IDE hard disk drive).
1.2 PCMC Overview
The PCMC (along with the LBX) provides three basic
functions: a cache controller, a main memory DRAM
controller, and a Host/PCI bridge. This section provides an overview of these functions. Note that, in
this document, operational descriptions assume that
the PCMC and LBX components are used together.
13
82434LX/82434NX
1.2.1 CACHE OPERATIONS
The PCMC provides the control for a second level
cache memory array implemented with either standard asynchronous SRAMs or synchronous burst
SRAMs. The data memory array is external to the
PCMC and located on the Host address/data bus.
Since the Pentium processor contains an internal
cache, there can be two separate caches in a Host
subsystem. The cache inside the Pentium processor
is referred to as the first level cache (also called
primary cache). A detailed description of the first level cache is beyond the scope of this document. The
PCMC cache control circuitry and associated external memory array is referred to as the second level
cache (also called secondary cache). The second
level cache is unified, meaning that both CPU data
and instructions are stored in the cache. The
82434LX PCMC supports both write-through and
write-back caching policies and the 82434NX supports write-back.
The optional second level cache memory array can
be either 256-KBytes or 512-KBytes in size. The
cache is direct-mapped and is organized as either
8K or 16K cache lines of 32 bytes per line.
In addition to the cache data RAM, the second level
cache contains a 4K set of cache tags that are internal to the PCMC. Each tag contains an address that
is associated with the corresponding data sector
(2 lines for a 256 KByte cache and 4 lines for a
512 KByte cache) and two status bits for each line in
the sector.
During a main memory read or write operation, the
PCMC first searches the cache. If the addressed
code or data is in the cache, the cycle is serviced by
the cache. If the addressed code or data is not in the
cache, the cycle is forwarded to main memory.
For the write-through (82434LX only) and write-back
(both 82434LX and 82434NX) policies, the cache
operation is determined by the CPU read or write
cycle as follows:
Write Cycle
If the caching policy is write-through and the write
cycle hits in the cache, both the cache and main
memory are updated. Upon a cache miss, only
main memory is updated. The cache is not updated (no write-allocate).
If the caching policy is write-back and the write
cycle hits in the cache, only the cache is updated;
main memory is not affected. Upon a cache miss,
only main memory is updated. The cache is not
updated (no write-allocate).
Read Cycle
Upon a cache hit, the cache operation is the same
for both write-through and write-back. In this case,
data is transferred from the cache to the CPU.
Main memory is not accessed.
290479 – 4
Figure 3. Second Level Cache Organization
14
82434LX/82434NX
If the read cycle causes a cache miss, the line
containing the requested data is transferred from
main memory to the cache and to the CPU. In the
case of a write-back cache, if the cache line fill is
to a sector containing one or more modified lines,
the modified lines are written back to main memory
and the new line is brought into the cache. For a
modified line write-back operation, the PCMC
transfers the modified cache lines to main memory
via a write buffer in the LBX. Before writing the last
modified line from the write buffer to main memory,
the PCMC updates the first and second level
caches with the new line, allowing the CPU access
to the requested data with minimum latency.
1.2.2.1 Read/Write Buffers
The LBX provides an interface for the CPU address
and data buses, PCI Address/Data bus, and the
main memory DRAM data bus. There are three posted write buffers and one read-prefetch buffers implemented in the LBXs to increase performance and to
maximize concurrency. The buffers are:
# CPU-to-Main Memory Posted Write Buffer
(4 Qwords)
# CPU-to-PCI Posted Write Buffer (4 Dwords)
# PCI-to-Main Memory Posted Write Buffer (2 x 4
Dwords)
# PCI-to-Main Memory Read Prefetch Buffer (line
1.2.1.1 Cache Consistency
The Snoop mechanism in the PCMC ensures data
consistency between cache (both first level and second level) and main memory. The PCMC monitors
PCI master accesses to main memory and when
needed, initiates an inquire (snoop) cycle to the first
and second level caches. The snoop mechanism
guarantees that consistent data is always delivered
to both the host CPU and PCI masters.
1.2.2 ADDRESS/DATA PATHS
Address paths between the CPU/cache and PCI
and data paths between the CPU/cache, PCI, and
main memory are supplied by two LBX components.
The LBX is a companion component to the PCMC.
Together, they form a Host/PCI bridge. The PCMC
(via the PCMC/LBX interface signals), controls the
address and data flow through the LBXs. Refer to
the LBX data sheet for more details on the address
and data paths.
Data is transferred to and from the PCMC internal
registers via the PCMC address lines. When the
Host CPU performs a write operation, the data is
sent to the LBXs. When the PCMC decodes the cycle as an access to one of its internal registers, it
asserts AHOLD to the CPU and instructs the LBXs
to copy the data onto the Host address lines. When
the PCMC decodes a Host read as an access to a
PCMC internal register, it asserts AHOLD to the
CPU. The PCMC then places the register data on its
address lines and instructs the LBX to copy the data
on the Host address bus to the Host data bus. When
the register data is on the Host data bus, the PCMC
negates AHOLD and completes the cycle.
buffer, 4 Qwords).
Refer to the LBX data sheet for details on the operation of these buffers.
1.2.3 HOST/PCI BRIDGE OPERATIONS
The PCMC permits the Host CPU to access devices
on the PCI Bus. These accesses can be to PCI I/O
space, PCI memory space, or PCI configuration
space.
As a PCI device, the PCMC can be either a master
initiating a PCI Bus operation or a target responding
to a PCI Bus operation. The PCMC is a PCI Bus
master for Host-to-PCI cycles and a target for PCIto-main memory transfers. Note that the PCMC does
not permit peripherals to be located on the Host
Bus. CPU I/O cycles, other than to PCMC internal
registers, are forwarded to the PCI Bus and PCI Bus
accesses to the Host Bus are not supported.
When the CPU initiates a bus cycle to a PCI device,
the PCMC becomes a PCI Bus master and translates the CPU cycle into the appropriate PCI Bus
cycle. The Host/PCI Posted write buffer in the LBXs
permits the CPU to complete CPU-to-PCI Dword
memory writes in three CPU clocks (1 wait-state),
even if the PCI Bus is currently busy. The posted
data is written to the PCI device when the PCI Bus is
available.
When a PCI Bus master initiates a main memory access, the PCMC (and LBXs) become the target of
the PCI Bus cycle and responds to the read/write
access. During PCI-to-main memory accesses, the
PCMC automatically performs cache snoop operations on the Host Bus, when needed, to maintain
data consistency.
15
82434LX/82434NX
As a PCI device, the PCMC contains all of the required PCI configuration registers. The Host CPU
reads and writes these registers as described in
Section 3.0, Register Description.
1.2.4 DRAM MEMORY OPERATIONS
The PCMC contains a DRAM controller that supports CPU and PCI master accesses to main memory. The PCMC DRAM interface supplies the control
signals and address lines and the LBXs supply the
data path. DRAM parity is generated for main memory writes and checked for memory reads.
For the 82434LX, the memory array is 64-bits wide
and ranges in size from 2 MBytes–192 MBytes. The
array can be implemented with either single-sided or
double-sided SIMMs. DRAM SIMM sizes of 256K x
36, 1M x 36, and 4M x 36 are supported.
For the 82434NX, the memory array is 64-bits wide
and ranges in size from 2 MBytes–512 MBytes. The
array can be implemented with either single-sided or
double-sided SIMMs. DRAM SIMM sizes of 256K x
36, 1M x 36, 4M x 36, and 16M x 36 are supported.
To provide optimum support for the various cache
configurations, and the resultant mix of bus cycles,
the system designer can select between 0-active
RASÝ and 1-active RASÝ modes. These modes affect the behavior of the RASÝ signal following either
CPU-to-main memory cycles or PCI-to-main memory
cycles.
The PCMC also provides programmable memory
and cacheability attributes on 14 memory segments
of various sizes in the ISA compatibility range
(512 KByte–1 MByte address range). Access rights
to these memory segments from the PCI Bus are
controlled by the expansion bus bridge.
The PCMC permits a gap to be created in main
memory within the 1 MByte–16 MBytes address
range, accommodating ISA devices which are
mapped into this range (e.g., ISA LAN card or an ISA
frame buffer).
16
1.2.5 3.3V SIGNALS
The 82434NX PCMC drives 3.3V signal levels on the
CPU and second level cache interfaces. Thus, no
extra logic (i.e. 5V/3.3V translation) is required when
interfacing to 3.3V processors and SRAMs. Six of
the power pins on the 82434NX are VDD3 pins.
These pins are connected to a 3.3V power supply.
The VDD3 pins power the output buffers on the CPU
and second level cache interfaces. The VDD3 pins
also power the output buffers for the HCLK [A-F]
outputs.
2.0 SIGNAL DESCRIPTIONS
This section provides a detailed description of each
signal. The signals are arranged in functional groups
according to their associated interface. The states of
all of the signals during hard reset are provided in
Section 8.0, System Clocking and Reset.
The ‘‘Ý’’ symbol at the end of a signal name indicates that the active, or asserted state occurs when
the signal is at a low voltage level. When ‘‘Ý’’ is not
present after the signal name, the signal is asserted
when at the high voltage level.
The terms assertion and negation are used extensively. This is done to avoid confusion when working
with a mixture of ‘‘active-low’’ and ‘‘active-high’’ signals. The term assert, or assertion indicates that a
signal is active, independent of whether that level is
represented by a high or low voltage. The term negate, or negation indicates that a signal is inactive.
The following notations are used to describe the signal type.
in
Input is a standard input-only signal
out Totem pole output is a standard active driver
o/d Open drain
Tri-State is a bi-directional, tri-state input/output pin
s/t/s Sustained tri-state is an active low tri-state signal owned and driven by one and only one
agent at a time. The agent that drives a s/t/s
pin low must drive it high for at least one clock
before letting it float. A new agent can not
start driving a s/t/s signal any sooner than
one clock after the previous owner tri-states it.
An external pull-up is required to sustain the
inactive state until another agent drives it and
must be provided by the central resource.
t/s
82434LX/82434NX
2.1 Host Interface
Signal
Type
Description
A [31:0]
t/s
ADDRESS BUS: A [31:0] are the address lines of the Host Bus. A [31:3] are connected to
the CPU A[31:3] lines and to the LBXs. A[2:0] are only connected to the LBXs. Along with
the byte enable signals, the A [31:3] lines define the physical area of memory or I/O being
accessed. During CPU cycles, the A [31:3] lines are inputs to the PCMC. They are used for
address decoding and second level cache tag lookup sequences. Also during CPU cycles,
A [2:0] are outputs and are generated from BE [7:0] Ý. A [27:24] provide hardware
strapping options for test features. For more details on theses options, refer to Section
11.0 Testability.
During inquire cycles, A [31:5] are inputs from the LBXs to the CPU and the PCMC to
snoop the first and the second level cache tags, respectively. In response to a Flush or
Flush Acknowledge Special Cycle, the PCMC asserts AHOLD and drives the addresses of
the second level cache lines to be written back to main memory on A [18:7] .
During CPU to PCI configuration cycles, the PCMC drives A [31:0] with the PCI
configuration space address that is internally derived from the CPU physical I/O address.
All PCMC internal configuration registers are accessed via A [31:0] . During CPU reads
from PCMC internal configuration registers, the PCMC asserts AHOLD and drives the
contents of the addressed register on A[31:0]. The PCMC then signals the LBXs to copy
this value from the address lines onto the host data lines. During writes to PCMC internal
configuration registers, the PCMC asserts AHOLD and signals the LBXs to copy the write
data onto the A [31:0] lines.
Finally, when in deturbo mode, the PCMC periodically asserts AHOLD and then drives
A [31:0] to valid logic levels to keep these lines from floating for an extended period of
time.
A [31:28] provide hardware strapping options at powerup. For more details on strapping
options, refer to Section 8.0, System Clocking and Reset. A [27:24] provide hardware
strapping options for test features. For more details on these options, refer to Section
11.0 Testability.
17
82434LX/82434NX
Signal
Type
Description
BE [7:0] Ý
in
BYTE ENABLES: The byte enables indicate which byte lanes on the CPU data bus
carry valid data during the current bus cycle. In the case of cacheable reads, all 8 bytes
of data are driven to the Pentium processor, regardless of the state of the byte enables.
The byte enable signals indicate the type of special cycle when M/IOÝ e D/CÝ e 0 and
W/RÝ e 1. During special cycles, only one byte enable is asserted by the CPU. The
following table depicts the special cycle types and their byte enable encodings:
Special Cycle Type
Shutdown
Flush
Halt/Stop Grant
Write Back
Flush Acknowledge
Branch Trace Message
Asserted Byte Enable
BE0Ý
BE1Ý
BE2Ý
BE3Ý
BE4Ý
BE5Ý
When the PCMC decodes a Shutdown Special Cycle, it asserts AHOLD, drives
000...000 (the PCI Shutdown Special Cycle Encoding) on the A [31:0] lines and signals
the LBXs to latch the host address bus. The PCMC then drives a Special Cycle on PCI,
signaling the LBXs to drive the latched address (00...00) on the AD [31:0] lines during
the data phase. The PCMC then asserts INIT for 16 HCLKs.
In response to Flush and Flush Acknowledge Special Cycles, the PCMC internally
inspects the Valid and Modified bits for each of the Second Level Cache Sectors. If a
line is both valid and modified, the PCMC drives the cache address of the line on the
A [18:7] and CAA/CAB [6:3] lines and writes the line back to main memory. The valid
and modified bits are both reset to 0. All valid and unmodified lines are simply marked
invalid.
In response to a write back special cycle, the PCMC simply returns BRDYÝ to the CPU.
The second level cache will be written back to main memory in response to the
following flush special cycle.
If BE2Ý is asserted during a special cycle, the 82434NX uses A4 to determine if the
cycle is a Halt or Stop Grant Special Cycle. If A4 e 0, the cycle is a Halt Special Cycle
and if A4 e 1, the cycle is a Stop Grant Special cycle.
In response to a halt special cycle, the PCMC asserts AHOLD, drives 000...001 (the PCI
halt special cycle encoding) on the A [31:0] lines, and signals the LBXs to latch the host
address bus. The PCMC then drives a special cycle on PCI, signaling the LBXs to drive
the latched address (00...01) on the AD [31:0] lines during the data phase.
When the 82434NX PCMC detects a CPU Stop Grant Special Cycle (M/IOÝ e 0,
D/CÝ e 0, W/RÝ e 1, A4 e 1, BE[7:0] Ý e FBh), it generates a PCI Stop Grant Special
cycle, with 0002h in the message field (AD [15:0] ) and 0012h in the message dependent
data field (AD [31:16] ) during the first data phase (IRDYÝ asserted).
ADSÝ
18
in
ADDRESS STROBE: The Pentium processor asserts ADSÝ to indicate that a new bus
cycle is beginning. ADSÝ is driven active in the same clock as the address, byte enable,
and cycle definition signals. The PCMC ignores a floating low ADSÝ that may occur
when BOFFÝ is asserted as the CPU is asserting ADSÝ.
82434LX/82434NX
Signal
Type
BRDYÝ
out
Description
BURST READY: BRDYÝ indicates that the system has responded in one of three ways:
1. valid data has been placed on the Pentium processor data pins in response to a read,
2. CPU write data has been accepted by the system, or
3. the system has responded to a special cycle.
NAÝ
out
NEXT ADDRESS: The PCMC asserts NAÝ for one clock when the memory system is
ready to accept a new address from the CPU, even if all data transfers for the current
cycle have not completed. The CPU may drive out a pending cycle two clocks after NAÝ
is asserted and has the ability to support up to two outstanding bus cycles.
AHOLD
out
ADDRESS HOLD: The PCMC asserts AHOLD to force the Pentium processor to stop
driving the address bus so that either the PCMC or LBXs can drive the bus. During PCI
master cycles, AHOLD is asserted to allow the LBXs to drive a snoop address onto the
address bus. If the PCI master locks main memory, AHOLD remains asserted until the
PCI master locked sequence is complete and the PCI master negates PLOCKÝ.
AHOLD is asserted during all accesses to PCMC internal configuration registers to allow
configuration register accesses to occur over the A [31:0] lines.
When in deturbo mode, the PCMC periodically asserts AHOLD to prevent the processor
from initiating bus cycles in order to emulate a slower system. The duration of AHOLD
assertion in deturbo mode is controlled by the Deturbo Frequency Control Register
(offset 51h). When PWROK is negated, the PCMC asserts AHOLD to allow the strapping
options on A [31:28] to be read. For more details on strapping options, see the System
Clocking and Reset section.
EADSÝ
out
EXTERNAL ADDRESS STROBE: The PCMC asserts EADSÝ to indicate to the Pentium
processor that a valid snoop address has been driven onto the CPU address lines to
perform an inquire cycle. During PCI master cycles, the PCMC signals the LBXs to drive a
snoop address onto the host address lines and then asserts EADSÝ to cause the CPU to
sample the snoop address.
INV
out
INVALIDATE: The INV signal specifies the final state (invalid or shared) that a first level
cache line transitions to in the event of a cache line hit during a snoop cycle. When
snooping the caches during a PCI master write, the PCMC asserts INV with EADSÝ.
When INV is asserted with EADSÝ, an inquire hit results in the line being invalidated.
When snooping the caches during a PCI master read, the PCMC does not assert INV with
EADSÝ. In this case, an inquire cycle hit results in a line transitioning to the shared state.
BOFFÝ
out
BACKOFF: The PCMC asserts BOFFÝ to force the Pentium processor to abort all
outstanding bus cycles that have not been completed and float its bus in the next clock.
The PCMC uses this signal to force the CPU to re-order a write-back due to a snoop cycle
around a currently outstanding bus cycle. The PCMC also asserts BOFFÝ to obtain the
CPU data bus for write-back cycles from the secondary cache due to a snoop hit. The
CPU remains in bus hold until BOFFÝ is negated.
HITMÝ
in
HIT MODIFIED: The Pentium processor asserts HITMÝ to inform the PCMC that the
current inquire cycle hit a modified line. HITMÝ is asserted by the Pentium processor two
clocks after the assertion of EADSÝ if the inquire cycle hits a modified line in the primary
cache.
19
82434LX/82434NX
Signal
M/IOÝ
D/CÝ
W/RÝ
Type
in
Description
BUS CYCLE DEFINITION (MEMORY/INPUT-OUTPUT, DATA/CONTROL, WRITE/
READ): M/IO, D/CÝ and W/RÝ define Host Bus cycles as shown in the table below.
M/IOÝ
Low
Low
Low
Low
High
High
High
High
D/CÝ
Low
Low
High
High
Low
Low
High
High
W/RÝ
Low
High
Low
High
Low
High
Low
High
Bus Cycle Type
Interrupt Acknowledge
Special Cycle
I/O Read
I/O Write
Code Read
Reserved
Memory Read
Memory Write
Interrupt acknowledge cycles are forwarded to the PCI Bus as PCI interrupt
acknowledge cycles (i.e. C/BE [3:0] Ý e 0000 during the address phase). All I/O cycles
and any memory cycles that are not directed to memory controlled by the PCMC DRAM
controller are forwarded to PCI. The Pentium processor generates six different types of
special cycles. The special cycle type is encoded on the BE [7:0] Ý lines.
HLOCKÝ
in
HOST BUS LOCK: The Pentium processor asserts HLOCKÝ to indicate the current bus
cycle is locked. HLOCKÝ is asserted in the first clock of the first locked bus cycle and is
negated after the BRDYÝ is returned for the last locked bus cycle. The Pentium
processor guarantees HLOCKÝ to be negated for at least one clock between back-toback locked operations. When a CPU locked cycle is directed to main memory, the
PCMC guarantees that once the locked operation begins in main memory, the CPU has
exclusive access to main memory (i.e., PCI master accesses to main memory will not be
initiated until the CPU locked operation completes). When a CPU locked cycle is
directed to PCI, the PCMC arbitrates for PLOCKÝ (PCI LOCKÝ) before initiating the
cycle on PCI, except when the cycle is to the memory range defined by the Frame
Buffer Range Register and the No Lock Requests bit in that register is set to 1.
CACHEÝ
in
CACHEABILITY: The Pentium processor asserts CACHEÝ to indicate the internal
cacheability of a read cycle or that a write cycle is a burst write-back cycle. If the CPU
drives CACHEÝ inactive during a read cycle, the returned data is not cached,
regardless of the state of KENÝ. The CPU asserts CACHEÝ for cacheable data reads,
cacheable code fetches, and cache line write-backs. CACHEÝ is driven along with the
cycle definition pins.
out
CACHE ENABLE: The PCMC asserts KENÝ to indicate to the CPU that the current
cycle is cacheable. KENÝ is asserted for all accesses to memory ranges 0 – 512-KBytes
and 1024-KBytes to the top of main memory controlled by the PCMC when the Primary
Cache Enable bit is set to 1, except in the following case: KENÝ is not asserted for
accesses to the top 64-KByte of main memory controlled by the PCMC when the
SMRAM Enable bit in the DRAM Control Register (Offset 57h) is set to 1 and the area is
not write protected. If the area is write protected and cacheable, KENÝ is asserted for
code read cycles, but is not asserted during data read cycle. KENÝ is asserted for any
CPU access within the range of 512-KBytes – 1024-KBytes if the corresponding Cache
Enable bit in the PAM [6:0] Registers (offsets 59h – 5Fh) is set to 1. When the Pentium
processor indicates that the current read cycle can be cached by asserting CACHEÝ
and the PCMC responds with KENÝ, the cycle is converted into a burst cache line fill.
The CPU samples KENÝ with the first of either BRDYÝ or NAÝ.
KENÝ
20
82434LX/82434NX
Signal
Type
SMIACTÝ
in
PENÝ
PCHKÝ
Description
SYSTEM MANAGEMENT INTERRUPT ACTIVE: The Pentium processor asserts
SMIACTÝ to indicate that the processor is operating in System Management Mode
(SMM). When the SMRAM Enable bit in the DRAM Control Register (offset 57h) is set
to 1, the PCMC allows CPU accesses SMRAM as permitted by the SMRAM Space
Register at configuration space offset 72h.
out
PARITY ENABLE: The PENÝ signal, along with the MCE bit in CR4 of the Pentium
processor, determines whether a machine check exception will be taken by the CPU as
a result of a parity error on a read cycle. The PCMC asserts PENÝ during DRAM read
cycles if the MCHK on DRAM/L2 Cache Data Parity Error Enable bit in the Error
Command Register (offset 70h) is set to 1. The PCMC asserts PENÝ during CPU
second level cache read cycles if the MCHK on DRAM/L2 Cache Data Parity Error
Enable and the L2 Cache Parity Enable bits in the Error Command Register (offset 70h)
are both set to 1.
in
DATA PARITY CHECK: PCHKÝ is sampled by the PCMC to detect parity errors on
CPU read cycles from main memory if the Parity Error Mask Enable bit in the DRAM
Control Register (offset 57h) is reset to 0. PCHKÝ is sampled by the PCMC to detect
parity errors on CPU read cycles from the second level cache if the L2 Cache Parity
Enable bit in the Error Command Register (offset 70h) is set to 1. If incorrect parity was
detected on a data read, the PCHKÝ signal is asserted by the Pentium processor two
clocks after BRDYÝ is returned. PCHKÝ is asserted for one clock for each clock in
which a parity error was detected.
21
82434LX/82434NX
2.2 DRAM Interface
Signal
Type
RAS [5:0] Ý
out
ROW ADDRESS STROBES: The RAS [5:0] Ý signals are used to latch the row
address on the MA[10:0] lines into the DRAMs. Each RAS[5:0] Ý signal corresponds
to one DRAM row. The 82434LX PCMC supports up to 6 rows in the DRAM array.
Each row is eight bytes wide. These signals drive the RASÝ lines of the DRAM array
directly, without external buffers.
RAS [7:6] Ý
out
ROW ADDRESS STROBES: The 82434NX supports up to eight rows of DRAM.
RAS [7:6] Ý are used with RAS [5:0] to latch the row address on the MA [11:0] lines
into the DRAMs. Each row is eight bytes wide. These signals drive the RASÝ lines of
the DRAM array directly, without external buffers.
CAS [7:0] Ý
out
COLUMN ADDRESS STROBES: The CAS [7:0] Ý signals are used to latch the
column address on the MA [10:0] lines into the DRAMs. Each CAS [7:0] Ý signal
corresponds to one byte of the eight byte-wide array. These signals drive the CASÝ
lines of the DRAM array directly, without external buffers. In a minimum configuration,
each CAS [7:0] Ý line only has one SIMM load, while the maximum configuration has 6
SIMM loads.
WEÝ
out
DRAM WRITE ENABLE: WEÝ is asserted during both CPU and PCI master writes to
main memory. During burst writes to main memory, WEÝ is asserted before the first
assertion of CAS [7:0] Ý and is negated with the last CAS [7:0] Ý. The WEÝ signal is
externally buffered to drive the WEÝ inputs on the DRAMs.
MA [10:0]
out
DRAM MULTIPLEXED ADDRESS: MA [10:0] provide the row and column address to
the DRAM array. The 82434LX uses MA [10:0] for the complete DRAM address bus.
The MA [10:0] lines are externally buffered to drive the multiplexed address lines of
the DRAM array.
MA11
out
DRAM MULTIPLEXED ADDRESS: MA11 provides the extra addressability for the
16M x 36 SiMMs that are supported by the 82434NX. MA [11:0] provide the row and
column address to the DRAM array. Like MA [10:0], MA11 is externally buffered to
drive the multiplexed address lines of the DRAM array.
22
Description
82434LX/82434NX
2.3 Cache Interface
Signal
Type
Description
CALE
out
CACHE ADDRESS LATCH ENABLE: CALE controls the external latch between the
host address lines and the cache address lines. CALE is asserted to open the
external latch, allowing the host address lines to propagate to the cache address
lines. CALE is negated to latch the cache address lines.
CADS [1:0] Ý,
CR/W [1:0] Ý
out
This signal pin has two functions, depending on the type of SRAMs used for the
second level cache.
CACHE ADDRESS STROBE: CADS [1:0] Ý are used with burst SRAMs. When
asserted, CADS [1:0] Ý cause the burst SRAMs to latch the cache address on the
rising edge of HCLK. CADS [1:0] Ý are glitch-free synchronous signals. CADS [1:0] Ý
functionality is selected by the SRAM type bit in the Secondary Cache Control
Register. Two copies of this signal are provided for timing reasons only.
CACHE READ/WRITE: CR/WÝ provide read/write control to the second level
cache when using asynchronous dual-byte select SRAMs. This functionality is
selected by the SRAM Type and Cache Byte Control Bits in the Secondary Cache
Control Register. The two copies of this signal are always driven to the same logic
level.
CADV [1:0] Ý,
CCS [1:0] Ý
out
This signal pin has two functions. The Cache Chip Select function is only enabled
when the SRAM connectivity bit (bit 2) in the SCC Register is set to 1.
CACHE ADVANCE: CADV [1:0] Ý are used with burst SRAMs to advance the
internal two bit address counter inside the SRAMs to the next address of the burst
sequence. Two copies of this signal are provided for timing reasons only. The two
copies are always driven to the same logic level.
CACHE CHIP SELECT: CCS [1:0] Ý are used with asynchronous SRAMs to deselect the SRAMs, placing them in a low power standby mode. When the CPU runs
a halt or stop grant special cycle, the 82434NX negates CCS [1:0] Ý, placing the
second level cache in a power saving mode. The PCMC then asserts CCS [1:0] Ý
(activating the SRAMs) when the CPU asserts ADSÝ.
When using burst SRAMs, only CCS1Ý implements the CCSÝ function. CADV0Ý
retains the address advance function. CCS1Ý serve two purposes with burst
SRAMs: 1) It is used (along with CADS [1:0] Ý) to place the SRAMs in a low power
standby mode. When the CPU runs a halt or stop grant special cycle, the 82434NX
negates CCS1Ý and asserts CADS [1:0] Ý for one clock, placing the SRAMs in a
power saving mode. The PCMC then asserts CCS1Ý so that the next ADSÝ from
the CPU places the SRAMs in an active mode. 2) CCS1Ý is used to block pipelined
cycles from the SRAMs when the SRAMs are servicing a cycle. After NAÝ is
asserted, the PCMC negates CCS1Ý preventing the SRAMs from sampling a new
address. CCS1Ý is asserted again when the SRAMs have completed the current
cycle.
CAA [6:3]
CAB [6:3]
out
CACHE ADDRESS [6:3] : CAA [6:3] and CAB [6:3] are connected to address lines
A [3:0] on the second level cache SRAMs. CAA [4:3] and CAB [4:3] are used with
standard SRAMs to advance through the burst sequence. CAA [6:5] and CAB [6:5]
are used during second level cache write-back cycles to address the modified lines
within the addressed sector. Two copies of these signals are provided for timing
reasons only. The two copies are always driven to the same logic level.
23
82434LX/82434NX
Signal
Type
Description
COE [1:0] Ý
out
CACHE OUTPUT ENABLE: COE [1:0] Ý are asserted when data is to be read from
the second level cache and are negated at all other times. Two copies of this signal
are provided for timing reasons only. The two copies are always driven to the same
logic level.
CWE[7:0] Ý,
CBS[7:0] Ý
out
This signal pin has two functions, depending on the type of SRAMs used for the
second level cache.
CACHE WRITE ENABLES: CWE [7:0] Ý are asserted to write data to the second
level cache SRAMs on a byte-by-byte basis. CWE7Ý controls the most significant
byte while CWE0Ý controls the least significant byte. These signals are cache write
enables when using burst SRAMs (SRAM Type bit in SCC Register is 1) or when
using asynchronous SRAMs (SRAM Type bit in SCC Register is 0) and the Cache
Byte Control Bit is 1.
CACHE BYTE SELECTS: The CBS [7:0] Ý lines provide byte control to the
secondary cache when using dual-byte select asynchronous SRAMs. These signals
are Cache Byte select lines when the SRAM Type and Cache Byte Control Bits in the
SCC Register are both 0.
2.4 PCI Interface
Signal
Type
Description
C/BE [3:0] Ý
t/s
PCI BUS COMMAND AND BYTE ENABLES: C/BE [3:0] Ý are driven by the current
bus master during the address phase of a PCI cycle to define the PCI command, and
during the data phase as the PCI byte enables. The PCI commands indicate the
current cycle type, and the PCI byte enables indicate which byte lanes carry
meaningful data. C/BE [3:0] Ý are outputs of the PCMC during CPU cycles that are
directed to PCI. C/BE [3:0] Ý are inputs when the PCMC acts as a slave. The
command encodings and types are listed below.
C/BE [3:0] Ý
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
24
Command
Interrupt Acknowledge
Special Cycle
I/O Read
I/O Write
Reserved
Reserved
Memory Read
Memory Write
Reserved
Reserved
Configuration Read
Configuration Write
Memory Read Multiple
Reserved
Memory Read Line
Memory Write and Invalidate
82434LX/82434NX
Signal
Type
Description
FRAMEÝ
s/t/s
CYCLE FRAME: FRAMEÝ is driven by the current bus master to indicate the
beginning and duration of an access. FRAMEÝ is asserted to indicate that a bus
transaction is beginning. While FRAMEÝ is asserted, data transfers continue. When
FRAMEÝ is negated, the transaction is in the final data phase. FRAMEÝ is an output
of the PCMC during CPU cycles which are directed to PCI. FRAMEÝ is an input to the
PCMC when the PCMC acts as a slave.
IRDYÝ
s/t/s
INITIATOR READY: The assertion of IRDYÝ indicates the current bus master’s ability
to complete the current data phase. IRDYÝ works in conjunction with TRDYÝ to
indicate when data has been transferred. On PCI, data is transferred on each clock
that both IRDYÝ and TRDYÝ are asserted. During read cycles, IRDYÝ is used to
indicate that the master is prepared to accept data. During write cycles, IRDYÝ is used
to indicate that the master has driven valid data on the AD [31:0] lines. Wait states are
inserted until both IRDYÝ and TRDYÝ are asserted together. IRDYÝ is an output of
the PCMC when the PCMC is the PCI master. IRDYÝ is an input to the PCMC when
the PCMC acts as a slave.
TRDYÝ
s/t/s
TARGET READY: TRDYÝ indicates the target device’s ability to complete the current
data phase of the transaction. It is used in conjunction with IRDYÝ. A data phase is
completed on each clock that TRDYÝ and IRDYÝ are both sampled asserted. During
read cycles, TRDYÝ indicates that valid data is present on AD [31:0] lines. During write
cycles, TRDYÝ indicates the target is prepared to accept data. Wait states are
inserted on the bus until both IRDYÝ and TRDYÝ are asserted together. TRDYÝ is an
output of the PCMC when the PCMC is the PCI slave. TRDYÝ is an input to the PCMC
when the PCMC is a master.
DEVSELÝ
s/t/s
DEVICE SELECT: When asserted, DEVSELÝ indicates that the driving device has
decoded its address as the target of the current access. DEVSELÝ is an output of the
PCMC when PCMC is a PCI slave and is derived from the MEMCSÝ input. MEMCSÝ
is generated by the expansion bus bridge as a decode to the main memory address
space. During CPU-to-PCI cycles, DEVSELÝ is an input. It is used to determine if any
device has responded to the current bus cycle, and to detect a target abort cycle.
Master-Abort termination results if no subtractive decode agent exists in the system,
and no one asserts DEVSELÝ within a programmed number of clocks.
STOPÝ
s/t/s
STOP: STOPÝ indicates that the current target is requesting the master to stop the
current transaction. This signal is used in conjunction with DEVSELÝ to indicate
disconnect, target-abort, and retry cycles. When PCMC is acting as a master on PCI, if
STOPÝ is sampled active on a rising edge of PCLKIN, FRAMEÝ is negated within a
maximum of 3 clock cycles. STOPÝ may be asserted by the PCMC in three cases. If a
PCI master attempts to access main memory when another PCI master has locked
main memory, the PCMC asserts STOPÝ to signal retry. The PCMC detects this
condition when sampling FRAMEÝ and LOCKÝ both active during an address phase.
When a PCI master is reading from main memory, the PCMC asserts STOPÝ when the
burst cycle is about to cross a cache line boundary. When a PCI master is writing to
main memory, the PCMC asserts STOPÝ upon filling either of the two PCI-to-main
memory posted write buffers. Once asserted, STOPÝ remains asserted until FRAMEÝ
is negated.
25
82434LX/82434NX
Signal
Type
Description
PLOCKÝ
s/t/s
PCI LOCK: PLOCKÝ is used to indicate an atomic operation that may require
multiple transactions to complete. PCI provides a mechanism referred to as
‘‘resource lock’’ in which only the target of the PCI transaction is locked. The
assertion of GNTÝ on PCI does not guarantee control of the PLOCKÝ signal.
Control of PLOCKÝ is obtained under its own protocol. When the PCMC is the PCI
slave, PLOCKÝ is sampled as an input on the rising edge of PCLKIN when FRAMEÝ
is sampled active. If PLOCKÝ is sampled asserted, the PCMC enters into a locked
state and remains in the locked state until PLOCKÝ is sampled negated on a
following rising edge of PCLKIN, when FRAMEÝ is sampled asserted.
REQÝ
out
GNTÝ
in
GRANT: When asserted, GNTÝ indicates that access to the PCI Bus has been
granted to the PCMC by the PCI Bus arbiter.
MEMCSÝ
in
MAIN MEMORY CHIP SELECT: When asserted, MEMCSÝ indicates to the PCMC
that a PCI master cycle is targeting main memory. MEMCSÝ is generated by the
expansion bus bridge. MEMCSÝ is sampled by the PCMC on the rising edge of
PCLKIN on the first and second cycle after FRAMEÝ has been asserted.
FLSHREQÝ
in
FLUSH REQUEST: When asserted, FLSHREQÝ instructs the PCMC to flush the
CPU-to-PCI posted write buffer in the LBXs and to disable further posting to this
buffer as long as FLSHREQÝ remains active. The PCMC acknowledges completion
of the CPU-to-PCI write buffer flush operation by asserting MEMACKÝ. MEMACKÝ
remains asserted until FLSHREQÝ is negated. FLSHREQÝ is driven by the
expansion bus bridge and is used to avoid deadlock conditions on the PCI Bus.
MEMREQÝ
in
MEMORY REQUEST: When asserted, MEMREQÝ instructs the PCMC to flush the
CPU-to-PCI and CPU-to-main memory posted write buffers and to disable posting in
these buffers as long as MEMREQÝ is active. The PCMC acknowledges completion
of the flush operations by asserting MEMACKÝ. MEMACKÝ remains asserted until
MEMREQÝ is negated. MEMREQÝ is driven by the expansion bus bridge.
MEMACKÝ
out
MEMORY ACKNOWLEDGE: When asserted, MEMACKÝ indicates the completion
of the operations requested by an active FLSHREQÝ and/or MEMREQÝ.
PAR
t/s
PARITY: PAR is an even parity bit across the AD [31:0] and C/BE [3:0] Ý lines. Parity
is generated on all PCI transactions. As a master, the PCMC generates even parity
on CPU writes to PCI, based on the PPOUT [1:0] inputs from the LBXs. During CPU
read cycles from PCI, the PCMC checks parity by checking the value sampled on the
PAR input with the PPOUT [1:0] inputs from the LBXs. As a slave, the PCMC
generates even parity on PAR, based on the PPOUT [1:0] inputs during PCI master
reads from main memory. During PCI master writes to main memory, the PCMC
checks parity by checking the value sampled on PAR with the PPOUT [1:0] inputs.
26
REQUEST: The PCMC asserts REQÝ to indicate to the PCI bus arbiter that the
PCMC is requesting use of the PCI Bus in response to a CPU cycle directed to PCI.
82434LX/82434NX
Signal
Type
Description
PERRÝ
s/t/s
PARITY ERROR: PERRÝ may be pulsed by any agent that detects a parity error during
an address phase, or by the master or the selected target during any data phase in which
the AD lines are inputs. The PERRÝ signal is enabled when the PERRÝ on Receiving
Data Parity Error bit in the Error Command Register (offset 70h) and the Parity Error
Enable bit in the PCI Command Register (offset 04h) are both set to 1.
When enabled, CPU-to-PCI write data is checked for parity errors by sampling the
PERRÝ signal two PCI clocks after data is driven. Also, when enabled, PERRÝ is
asserted by the PCMC when it detects a data parity error on CPU read data from PCI and
PCI master write data to main memory. PERRÝ is neither sampled nor driven by the
PCMC when either the PERRÝ on Receiving Data Parity Error bit in the Error Command
Register or the Parity Error Enable bit in the PCI Command Register is reset to 0.
SERRÝ
o/d
SYSTEM ERROR: SERRÝ may be pulsed by any agent for reporting errors other than
parity. SERRÝ is asserted by the PCMC whenever a serious system error (not
necessarily a PCI error) occurs. The intent is to have the PCI central agent (for example,
the expansion bus bridge) assert NMI to the processor. Control over the SERRÝ signal is
provided via the Error Command Register (offset 70h) when the Parity Error Enable bit in
the PCI Command Register (offset 04h) is set to 1. When the SERRÝ DRAM/L2 Cache
Data Parity Error bit is set to 1, SERRÝ is asserted upon detecting a parity error on CPU
read cycles from DRAM. If the L2 Cache Parity bit is also set to 1, SERRÝ will be
asserted upon detecting a parity error on CPU read cycles from the second level cache.
The Pentium processor indicates these parity errors to the PCMC via the PCHKÝ signal.
When the SERRÝ on PCI Address Parity Error bit is set to 1, the PCMC asserts SERRÝ if
a parity error is detected during the address phase of a PCI master cycle.
When the SERRÝ on Received PCI Data Parity bit is set to 1, the PCMC asserts SERRÝ
if a parity error is detected on PCI during a CPU read from PCI. During CPU to PCI write
cycles, when the SERRÝ on Transmitted PCI Data Parity Error bit is set to 1, the PCMC
asserts SERRÝ in response to sampling PERRÝ active. When the SERRÝ on Received
Target Abort bit is set to 1, the PCMC asserts SERRÝ when the PCMC receives a target
abort on a PCMC initiated PCI cycle. If the Parity Error Enable bit in the PCI Command
Register is reset to 0, SERRÝ is disabled and is never asserted by the PCMC.
27
82434LX/82434NX
2.5 LBX Interface
Signal
Type
Description
HIG [4:0]
out
HOST INTERFACE GROUP: HIG [4:0] are outputs of the PCMC used to control the
LBX HA (Host Address) and HD (Host Data) buses. Commands driven on HIG[4:0]
cause the host data and/or address lines to be either driven or latched by the LBXs.
See the 82433LX (LBX) Local Bus Accelerator Data Sheet for a listing of the
HIG [4:0] commands.
MIG [2:0]
out
MEMORY INTERFACE GROUP: MIG [2:0] are outputs of the PCMC and control the
LBX MD (Memory Data) bus. Commands driven on the MIG [2:0] lines cause the
memory data lines to be either driven or latched by the LBXs. See the 82433LX (LBX)
Local Bus Accelerator Data Sheet for a listing of the MIG[2:0] commands.
MDLE
out
MEMORY DATA LATCH ENABLE: During CPU reads from main memory, MDLE is
used to control the latching of memory read data on the CPU data bus. MDLE is
negated as CAS [7:0] Ý are negated to close the latch between the memory data bus
and the host data bus. During CPU reads from main memory, the PCMC closes the
memory data to host data latch in the LBXs as BRDYÝ is asserted and opens the
latch after the CPU has sampled the data.
PIG[3:0]
out
PCI INTERFACE GROUP: PIG[3:0] are outputs of the PCMC used to control the LBX
AD (PCI Address/Data) bus. Commands driven on the PIG [3:0] lines cause the AD
lines to be either driven or latched. See the 82433LX (LBX) Local Bus Accelerator
Data Sheet for a listing of the PIG [3:0] commands.
DRVPCI
out
DRIVE PCI: DRVPCI acts as an output enable for the LBX AD lines. When sampled
asserted, the LBXs begin driving the PCI AD lines. When negated, the AD lines on
the LBXs are tri-stated. The LBX AD lines are tri-stated asynchronously from the
falling edge of DRVPCI.
EOL
in
END OF LINE: EOL is asserted by the low order LBX when a PCI master read or
write transaction is about to overrun a cache line boundary. EOL has an internal pullup resistor inside the PCMC. The low order LBX EOL signal connects to this PCMC
input. The high order LBX EOL signal is connected to ground through an external
pull-down resistor.
PPOUT [1:0]
in
PCI PARITY OUT: These signals reflect the parity of the 32 AD lines driven from or
latched in the LBXs, depending on the command driven on PIG [3:0] . The PPOUT0
pin has a weak internal pull-down resistor. The PPOUT1 pin has a weak internal pullup resistor.
2.6 Reset And Clock
Signal
HCLKOSC
HCLKA–HCLKF
28
Type
Description
in
HOST CLOCK OSCILLATOR: The HCLKOSC input is driven externally by a
crystal oscillator. The PCMC generates six copies of HCLK from HCLKOSC
(HCLKA–HCLKF). During power-up, HCLKOSC must stabilize for 1 ms before
PWROK is asserted. If an external clock driver is used to clock the CPU, PCMC,
LBXs and second level cache SRAMs instead of the HCLKA – HCLKF outputs,
HCLKOSC must be tied either high or low.
out
HOST CLOCK OUTPUTS: HCLKA – HCLKF are six low skew copies of the host
clock. These outputs eliminate the need for an external low skew clock driver.
82434LX/82434NX
Signal
Type
Description
HCLKIN
in
HOST CLOCK INPUT: All timing on the host, DRAM and second level cache interfaces
is based on HCLKIN. If an external clock driver is used to clock the CPU, PCMC, LBXs
and second level cache SRAMs, the externally generated clock must be connected to
HCLKIN. During power-up HCLKIN must stabilize for 1 ms before PWROK is asserted.
CPURST
out
CPU HARD RESET: The CPURST pin is asserted in response to one of two conditions.
Powerup
82434LX: During powerup the 82434LX asserts CPURST when PWROK is negated.
When PWROK is asserted, the 82434LX first ensures that it has been initialized before
negating CPURST.
82434NX: During powerup, the 82434NX PCMC negates CPURST while PWROK is
negated. When PWROK is asserted, the 82434NX asserts CPURST for 2 ms.
Software
CPURST is also asserted when the System Hard Reset Enable bit in the Turbo-Reset
Control Register (I/O address 0CF9h) is set to 1 and the Reset CPU bit toggles from 0
to 1 (82434LX and 82434NX). CPURST is driven synchronously to the rising edge of
HCLKIN.
INIT
PWROK
PCLKOUT
out
INITIALIZATION: INIT is asserted in response to any one of two conditions. When the
System Hard Reset Enable bit in the Turbo-Reset Control Register is reset to 0 and the
Reset CPU bit toggles from 0 to 1, the PCMC initiates a soft reset by asserting INIT.
The PCMC also initiates a soft reset by asserting INIT in response to a shutdown
special cycle. In both cases, INIT is asserted for a minimum of 2 Host clocks.
in
POWER OK: When asserted, PWROK is an indication to the PCMC that power and
HCLKIN have stabilized for at least 1 ms. PWROK can be driven asynchronously.
82434LX: When PWROK is negated, the 82434LX asserts both CPURST and
PCIRSTÝ. When PWROK is driven high, the 82434LX ensures that it is initialized
before negating CPURST and PCIRSTÝ.
82434NX: When PWROK is negated, the 82434NX negates CPURST and asserts
PCIRSTÝ. When PWROK is asserted, the 82434NX asserts CPURST for 2 ms.
PCIRSTÝ is negated 1 ms after PWROK is asserted.
out
PCI CLOCK OUTPUT: PCLKOUT is internally generated by a Phase Locked Loop
(PLL) that divides the frequency of HCLKIN by 2. This output must be buffered
externally to generate multiple copies of the PCI Clock. One of the copies must be
connected to the PCLKIN pin.
29
82434LX/82434NX
Signal
PCLKIN
PCIRSTÝ
Type
Description
in
PCI CLOCK INPUT: An internal PLL locks PCLKIN in phase with HCLKIN. All timing on
the PCMC PCI interface is referenced to the PCLKIN input. All output signals on the PCI
interface are driven from PCLKIN rising edges and all input signals on the PCI interface
are sampled on PCLKIN rising edges.
out
PCI RESET: PCIRSTÝ is asserted to initiate hard reset on PCI. PCIRSTÝ is asserted in
response to one of two conditions.
Power-up
During power-up the PCMC asserts PCIRSTÝ when PWROK is negated.
82434LX: When PWROK is asserted the PCMC will first ensure that it has been
initialized before negating PCIRSTÝ.
82434NX: When PWROK is negated, the 82434NX asserts PCIRSTÝ. The 82434NX
then negates PCIRSTÝ 1 ms after PWROK is asserted.
Software
PCIRSTÝ is also asserted when the System Hard Reset Enable bit in the Turbo/Reset
Control Register is set to 1 and the Reset CPU bit toggles from 0 to 1 (82434LX and
82434NX). PCIRSTÝ is driven asynchronously.
TESTEN
in
TEST ENABLE: TESTEN must be tied low for normal system operation.
3.0 REGISTER DESCRIPTION
The 82434LX/82434NX PCMC contains two sets of software accessible registers. These registers are accessed via the Host CPU I/O address space. The PCMC also contains a set of configuration registers that
reside in PCI configuration space and are used to specify PCI configuration, DRAM configuration, cache
configuration, operating parameters and optional system features (see Section 3.2, PCI Configuration Space
Mapped Registers). The PCMC internal registers (both I/O Mapped and Configuration registers) are only
accessible by the Host CPU and cannot be accessed by PCI masters. The registers can be accessed as Byte,
Word (16-bit), or Dword (32-bit) quantities. All multi-byte numeric fields use ‘‘little-endian’’ ordering (i.e., lower
addresses contain the least significant parts of the field).
Some of the PCMC registers described in this section contain reserved bits. These bits are labeled ‘‘R’’.
Software must deal correctly with fields that are reserved. On reads, software must use appropriate masks to
extract the defined bits and not rely on reserved bits being any particular value. On writes, software must
ensure that the values of reserved bit positions are preserved. That is, the values of reserved bit positions
must first be read, merged with the new values for other bit positions and then written back.
In addition to reserved bits within a register, the PCMC contains address locations in the PCI configuration
space that are marked ‘‘Reserved’’ (Table 1). The PCMC responds to accesses to these address locations by
completing the Host cycle. When a reserved register location is read, 0000h is returned. Writes to reserved
registers have no affect on the PCMC.
Upon receiving a hard reset via the PWROK signal, the PCMC sets its internal configuration registers to
predetermined default states. The default state represents the minimum functionality feature set required to
successfully bring up the system. Hence, it does not represent the optimal system configuration. It is the
responsibility of the system initialization software (usually BIOS) to properly determine the DRAM configurations, cache configuration, operating parameters and optional system features that are applicable, and to
program the PCMC registers accordingly.
30
82434LX/82434NX
The following nomenclature is used for access attributes.
RO
R/W
Read Only. If a register is read only, writes to this register have no effect.
Read/Write. A register with this attribute can be read and written.
R/WC Read/Write Clear. A register bit with this attribute can be read and written. However, a write of a 1
clears (sets to 0) the corresponding bit and a write of a 0 has no effect.
3.1 I/O Mapped Registers
The 82434LX PCMC contains three registers that reside in the CPU I/O address spaceÐthe Configuration
Space Enable (CSE) Register, the Turbo-Reset Control (TRC) Register and the Forward (FORW) Register.
These registers can not reside in PCI configuration space because of the special functions they perform. The
CSE Register enables/disables the configuration space and, hence, can not reside in that space. The TRC
Register enables/disables deturbo mode which effectively slows the processor to accommodate software
programs that rely on the slow speed of PC/XT systems to time certain events. The FORW Register determines which of the possible hierarchical PCI Buses a cycle is directed. The 82434LX uses mechanism Ý2 for
accessing PCI configuration space.
The 82434NX PCMC contains five registers that reside in the CPU I/O address spacethe Configuration Address (CONFADD) Register, the Configuration Space Enable (CSE) Register, the Turbo-Reset Control (TRC)
Register, the Forward (FORW) Register, and the PCI Mechanism Control (PMC) Register. The CSE, TRC, and
FORW Registers are the same for both the 82434LX and 82434NX PCMCs. The 82434NX can use either
Configuration Access Mechanism Ý1 or Ý2 for accessing PCI configuration space. When Configuration Access Mechanism Ý1 is used (See Section 3.2, PCI Configuration Space Mapped Registers), The CONFADD
Register enables/disables the configuration space and determines what portion of configuration space is
visible through the Configuration Data (CONFDATA) window. The CSE and FORW Registers are used for
Configuration Access Mechanism Ý2. The PCI Mechanism Control (PMC) Register selects whether Configuration Access Mechanism 1 or 2 is used (see the Rev 2.0 PCI Local Bus Specification).
3.1.1 CONFADDÐCONFIGURATION ADDRESS REGISTER
I/O Address:
Default Value:
Access:
Size:
0CF8h Accessed as a Dword
00000000h
Read/Write
32 bits
CONFADD is a 32-bit register used in Configuration Access Mechanism Ý1. It is accessed only when referenced as a Dword and PCAMS in the PMC Register is set to 1. Byte or Word references ‘‘pass through’’ the
CONFADD Register to the I/O locations ‘‘behind’’ it. For example a byte access to 0CF8h will access the CSE
Register, while a word access to CF8h will access both the CSE and TRC Registers. The CONFADD Register
contains the Bus Number, Device Number, Function Number, and Register Number where the CONFDATA
window is located.
31
82434LX/82434NX
Bit
Description
31
CONFIGURATION ENABLE (CONE)ÐR/W: When CONE e 1, accesses to PCI configuration
space are enabled, if the PCAMS bit of the PMC register is also 1. When CONE e 0, accesses to PCI
configuration space are disabled, if the PCAMS bit is 1. If the PCAMS bit is 0, this bit has no effect.
30:24
RESERVED
23:16
BUS NUMBER (BUSNUM)ÐR/W: When the BUSNUM is programmed to 00h, the target of the
Configuration Cycle is either the PCMC or the PCI Local Bus that is directly connected to the PCMC.
PCI Access Mechanism Ý1 can generate either type 0 or type 1 configuration cycles on PCI. A type
0 Configuration Cycle is generated on PCI if the Bus Number is programmed to 00h and the PCMC
is not the target. If the Bus Number is non-zero a type 1 configuration cycle is generated on PCI with
the Bus Number mapped to AD [23:16] during the address phase.
15:11
DEVICE NUMBER (DEVNUM)ÐR/W: This field selects one agent on the PCI Bus selected by the
Bus Number. During a Type 1 Configuration cycle this field is mapped to AD [15:11] . During a Type 0
Configuration Cycle this field is decoded and one of AD [31:17] is driven to a 1. The PCMC is always
Device Number 0.
10:8
FUNCTION NUMBER (FUNCNUM)ÐR/W: This field is mapped to AD [10:8] during PCI
configuration cycles. This allows the configuration registers of a particular function in a multifunction device to be accessed.
7:2
REGISTER NUMBER (REGNUM)ÐR/W: This field selects one register within a particular Bus,
Device, and Function as specified by the other fields in the Configuration Address Register.
REGNUM is mapped to AD [7:2] during PCI configuration cycles.
1:0
RESERVED
3.1.2 CSEÐCONFIGURATION SPACE ENABLE REGISTER
I/O Address:
Default Value:
Attribute:
Size:
0CF8h
00h
Read/Write
8 bits
The CSE Register enables/disables configuration space access and provides access to specific functions
within a PCI agent. The register is located in the CPU I/O address space. The PCMC, as a Host/PCI Bridge,
supports multi-function devices on the PCI Bus. The function number permits individual configuration spaces
for up to eight functions within an agent. The register is located in the CPU I/O address space.
Bit
Description
7:4
KEY FIELD (KEY)ÐR/W: This field is used only when the PCI Mechanism Control Register (PMC)
indicates Configuration Access Mechanism 2 is to be used. When the key field is programmed to 0h,
the PCI configuration space is disabled. When the key field is programmed to a non-zero value, all
CPU accesses to CnXXh (where n is a non zero value) are forwarded to PCI as configuration space
accesses. Additionally, when the key field is programmed to a non-zero value, all CPU accesses to
C0XXh are intercepted by the PCMC and directed to a PCMC internal register.
3:1
FUNCTION NUMBER (FN)ÐR/W: For multi-function devices, this field selects a particular function
within a PCI device. During a configuration cycle, bits [3:1] become part of the PCI Bus address and
correspond to AD [10:8] .
0
RESERVED
32
82434LX/82434NX
3.1.3 TRCÐTURBO-RESET CONTROL REGISTER
I/O Address:
Default Value:
Attribute:
Size:
0CF9h
00h
Read/Write
8 bits
The TRC Register is an 8-bit read/write register that selects turbo/deturbo mode of the CPU, initiates PCI Bus
and CPU reset cycles, and initiates the CPU Built In Self Test (BIST). TRC is located in CPU I/O address
space.
Bit
Description
7:3
RESERVED
2
RESET CPU (RCPU)ÐR/W: RCPU is used to initiate a hard reset or soft reset to the CPU. During a
hard reset, the PCMC asserts CPURST and PCIRSTÝ. The PCMC initiates a hard reset when this
register is programmed for a hard reset or when the PWROK signal is asserted. During a soft reset, the
PCMC asserts INIT. The PCMC initiates a soft reset when this register is programmed for a soft reset
and in response to a shutdown special cycle.
Note that a hard reset initializes the entire system and invalidates the CPU cache. A soft reset
initializes only the CPU. The contents of the CPU cache are unaffected.
This bit is used in conjunction with bit 1 of this register. Bit 1 must be set up prior to writing a 1 to this
register. Thus, two write operations are required to initiate a reset using this bit. The first write
operation programs bit 1 to the appropriate state while setting this bit to 0. The second write operation
keeps bit 1 at the programmed state (1 or 0) while setting this bit to a 1. When RCPU transitions from a
0 to a 1, a hard reset is initiated if bit 1 e 1 and a soft reset is initiated if bit 1 e 0.
1
SYSTEM HARD RESET ENABLE (SHRE)ÐR/W: This bit is used in conjunction with bit 2 of this
register to initiate either a hard or soft reset. When SHRE e 1, the PCMC initiates a hard reset to the
CPU when bit 2 transitions from 0 to 1. When SHRE e 0, the PCMC initiates a soft reset when bit 2
transitions from 0 to 1.
0
DETURBO MODE (DM)ÐR/W: This bit enables and disables deturbo mode. When DM e 1, the PCMC
is in the deturbo mode. In this mode, the PCMC periodically asserts the AHOLD signal to slow down
the effective speed of the CPU. The AHOLD duty cycle is programmable through the Deturbo
Frequency Control (DFC) Register. When DM e 0, the deturbo mode is disabled.
Deturbo mode can be used to maintain backward compatibility with older software packages that rely
on the operating speed of older processors. For accurate speed emulation, caching should be
disabled. If caching is disabled during runtime, the following steps should be performed to make sure
that modified lines have been flushed from the cache to main memory before entering deturbo mode.
Disable the primary cache via the PCE bit in the HCS Register. This prevents the KENÝ signal from
being asserted, which prevents any further first and second level cache line fills. At this point, software
executes the WBINVD instruction to flush the caches, and then sets DM to 1. When exiting the deturbo
mode, the system software must first set DM to 0, then enable first and second level caching by writing
to the HCS Register.
33
82434LX/82434NX
3.1.4 FORWÐFORWARD REGISTER
I/O Address:
Default Value:
Attribute:
Size:
0CFAh
00h
Read/Write
8 Bits
This 8-bit register specifies which PCI Bus configuration space is enabled in a multiple PCI Bus configuration.
The default value for the FORW Register enables the configuration space of the PCI Bus connected to the
PCMC.
Bit
Description
7:0
FORWARD BUS NUMBERÐR/W: When this register value is 00h, the configuration space of the PCI
Bus connected to the PCMC is enabled and the PCMC initiates a type 0 configuration cycle. If the
value of this register is not 00h, the PCMC initiates a type 1 configuration cycle to forward the cycle
(via one or more PCI/PCI Bridges) to the PCI Bus specified by the contents of this register. For nonzero values, bits [7:0] are mapped to AD [23:16] , respectively.
3.1.5 PMCÐPCI MECHANISM CONTROL REGISTER
I/O Address:
Default Value:
Access:
Size:
0CFBh
00h
Read/Write
8 bits
The PMC Register selects whether PCI Configuration Access Mechanism 1 or 2 is to be used. The register is
located in the CPU I/O address space.
Bit
Description
7:1
RESERVED
0
PCI CONFIGURATION ACCESS MECHANISM SELECT (PCAMS)ÐR/W: When PCAMS e 0, the
PCMC uses to PCI Configuration Access Mechanism Ý2. When PCAMS e 1, the PCMC uses to PCI
Configuration Access Mechanism Ý1. The CONFADD and CONFDATA Registers are only accessible
when PCAMS e 1.
3.1.6 CONFDATAÐCONFIGURATION DATA REGISTER
I/O Address:
Default Value:
Access:
Size:
0CFCh
00h
Read/Write
32 bits
CONFDATA is a 32 bit read/write window into configuration space. The portion of configuration space that is
referenced by CONFDATA is determined by the contents of CONFADD.
Bit
31:0
34
Description
CONFIGURATION DATA WINDOW (CDW)ÐR/W: When using Configuration Access Mechanism
Ý1 if bit 31 of CONFADD is 1 any I/O reference that falls in the CONFDATA I/O space will be
mapped to configuration space using the contents of CONFADD.
82434LX/82434NX
3.2 PCI Configuration Space Mapped Registers
The PCI Bus defines a slot based ‘‘configuration space’’ that allows each device to contain up to 256 8-bit
configuration registers. The PCI specification defines two bus cycles to access the PCI configuration spaceÐ
Configuration Read and Configuration Write. While memory and I/O spaces are supported by the Pentium
processor, configuration space is not supported. For PCI configuration space access, the PCMC translates the
Pentium processor I/O cycles into PCI configuration cycles. Table 1 shows the PCMC configuration space.
Table 1. PCMC Configuration Space
Address
Offset
Register
Symbol
00–01h
VID
Vendor Identification
RO
02–03h
DID
Device Identification
RO
04–05h
PCICMD
Command Register
R/W
06–07h
PCISTS
Status Register
RO, R/WC
08h
RID
Revision Identification
RO
09h
RLPI
Register-Level Programming Interface
RO
0Ah
SCCD
Sub-Class Code
RO
0Bh
BCCD
Base Class Code
RO
0Ch
Ð
0Dh
0Eh
0Fh
10–4Fh
MLT
Ð
BIST
Ð
Register Name
Access
Reserved
Master Latency Timer
Ð
R/W
Reserved
BIST Register
Reserved
Ð
50h
HCS
51h
DFC
Deturbo Frequency Control
R/W
52h
SCC
Secondary Cache Control
R/W
53h
HBC
Host Read/Write Buffer Control
R/W
54h
PBC
PCI Read/Write Buffer Control
R/W
55h
56h
Host CPU Selection
Ð
RO
Ð
Reserved
Ð
Reserved
R/W
Ð
Ð
57h
DRAMC
DRAM Control
R/W
58h
DRAMT
DRAM Timing
R/W
59–5Fh
PAM [6:0]
Programmable Attribute Map (7 Registers)
R/W
60–65h
DRB [5:0]
DRAM Row Boundary (6 Registers)
R/W
66–67h
DRB [7:6]
DRAM Row Boundary (2 Registers)
R/W
68–6Bh
DRBE
DRAM Row Boundary Extension
R/W
6C–6Fh
Ð
70h
ERRCMD
Reserved
Error Command
Ð
R/W
35
82434LX/82434NX
Table 1. PCMC Configuration Space (Continued)
Address
Offset
Register
Symbol
71h
ERRSTS
72h
SMRS
73–77h
Ð
78–79h
MSG
7A–7B
7C–7Fh
Ð
FBR
80–FFh
Ð
Register Name
Access
Error Status
R/WC
SMRAM Space Control
R/W
Reserved
Memory Space Gap
Reserved
Frame Buffer Range
Reserved
Ð
R/W
Ð
R/W
Ð
NOTE:
Shaded rows indicate register differences between the 82434LX and 82434NX devices. For non-shaded rows, the registers
are the same for the two devices.
3.2.1 CONFIGURATION SPACE ACCESS MECHANISM
The 82434LX supports Configuration Space Access Mechanism Ý2 and the 82434NX supports both configuration space access mechanisms Ý1 and Ý2. The mechanism is selected via the PCAMS bit in the PMC
Register. The bus cycles used to access PCMC internal configuration registers are described in Section 7.0,
PCI Interface.
3.2.1.1 Access Mechanism Ý1:
For configuration access mechanism Ý1, the 82434NX PCMC uses the CONFADD and CONFDATA Registers. Note that while the CONFADD and PMC Register address spaces overlap, the CONFADD Register is
referenced only by a Dword read or write to CF8h. This allows the PMC Register to be accessed by a byte
write to CFBh, even when using configuration access mechanism Ý1.
To reference a configuration register with access mechanism Ý1, a Dword I/O write loads the CONFADD
Register with a 32-bit value that specifies the PCI Bus, the device on that bus, the function within the device,
and a specific configuration register of the device function being accessed (Figure 4). Bit 31 of the CONFADD
Register must be 1 to enable a configuration cycle. CONFDATA then becomes a four byte window of configuration space specified by the contents of the CONFADD Register. A read or write to CONFDATA results in the
PCMC translating CONFADD into a PCI configuration cycle.
Type 0 Access
If the BUSNUM field is 0, a Type 0 configuration cycle is performed on the PCI. Bus CONFADD [10:2] are
mapped directly to AD [10:2] . The DEVNUM field is decoded onto AD [31:17] and AD [15:11] (for accesses to
device 1, AD17 is asserted; for accesses to device Ý2, AD18 is asserted; etc.). The PCMC is Device Ý0 and
does not pass its configuration cycles to the PCI Bus. Thus, AD16 is never asserted. For accesses to device
15, AD31 is asserted, etc. This mapping allows the same Device Number to activate the same AD line in either
configuration access mechanism. All other AD lines are 0.
36
82434LX/82434NX
290479 – 5
Figure 4. Mechanism Ý1 Type 0 Configuration Address to PCI Address Mapping
Type 1 Access
If the BUSNUM field of the CONFADD Register is non-zero, a Type 1 configuration cycle is performed on the
PCI Bus. CONFADD [23:2] are mapped directly to AD [23:2] (Figure 5). AD [1:0] are driven to 01 to indicate a
Type 1 Configuration cycle. All other lines are driven to 0.
290479 – 6
Figure 5. Mechanism Ý1 Type 1 Configuration Address to PCI Address Mapping
3.2.1.2 Access Mechanism Ý2
The 82434LX/82434NX PCMC uses the CSE and Forward Registers for configuration access mechanism Ý2.
When PCI configuration space is enabled via the CSE Register, the PCMC maps PCI configuration space into
4-KBytes of CPU I/O space. Each PCI device has its own 256-Byte configuration space. When configuration
space is enabled, CPU accesses to I/O locations CXXXh are translated into configuration space accesses. In
this mode, the PCMC translates all I/O cycles in the C100h – CFFFh range into configuration cycles on the PCI
Bus. I/O accesses within the C000h–C0FFh range are intercepted by the PCMC and are directed to the
PCMC internal configuration registers. These cycles are not forwarded to the PCI Bus.
When configuration space access is disabled, CPU accesses to I/O locations CXXXh are forwarded to the PCI
Bus I/O space. CPU cycles to I/O locations other than CXXXh are unaffected by whether the configuration
mode is enabled or disabled. These cycles are always treated as ordinary I/O cycles by the PCMC.
37
82434LX/82434NX
Type 0 Access
If the Forward Register contains 00h a Type 0 configuration access is generated on the PCI Bus (Figure 6). For
type 0 configuration cycles, AD[1:0] e 00. Host CPU address bits A[7:2] are not translated and become
AD [7:2] on the PCI Bus. AD [7:2] select one of the 256 8-bit I/O locations in the PCI configuration space. The
FUNCTION NUMBER field from the CSE Register (CSE [3:1] ) is driven on AD [10:8] . Host CPU address bits
A [11:8] are mapped to an IDSEL input for each of the 16 possible PCI devices. The IDSEL input for each PCI
device must be hard-wired to one of the AD [31:16] signals on the PCI Bus. AD16 is reserved for the PCMC.
When CPU address A [11:8] e Fh, PCI address bits A31 e 1 and A [30:16] e 00h. Other devices on the PCI Bus
should not use AD16. Note that when A [11:8] e 0h, an access to the PCMC internal registers occurs and the
cycle is not forwarded to the PCI Bus.
290479 – 7
Figure 6. Mechanism Ý2 Type 0 Host-to-PCI Address Mapping
38
82434LX/82434NX
Type 1 Access
If the Forward Register is non-zero a Type 1 configuration access is generated on PCI. For type 1 configuration
cycles, AD[1:0] e 01. AD[10:2] are generated the same as for the type 0 configuration cycle. Host CPU
address bits A [11:8] contain the specific device number and are mapped to AD [14:11] . AD [23:16] contain the
Bus Number of the PCI Bus that is to be accessed and corresponds to the Forward Address Register bits
[7:0] .
During a Type 1 configuration access AD [1:0] e 01 (Figure 7). The Register Index and Function Number are
mapped to the AD lines the same way in Type 1 configuration access as in a Type 0 configuration access.
CPU address bits A [11:8] are mapped directly to PCI lines AD [14:11] as the Device Number. The contents of
the Forward Register are mapped to AD [23:16] to form the Bus Number.
290479 – 8
Figure 7. Mechanism Ý2 Type 1 Host-to-PCI Address Mapping
39
82434LX/82434NX
3.2.2 VIDÐVENDOR IDENTIFICATION REGISTER
Address Offset:
Default Value:
Attribute:
Size:
00–01h
8086h
Read Only
16 bits
The VID Register contains the vendor identification number. This 16-bit register combined with the Device
Identification Register uniquely identify any PCI device. Writes to this register have no effect.
Bits
15:0
Description
VENDOR IDENTIFICATION NUMBER: This is a 16-bit value assigned to Intel.
3.2.3 DIDÐDEVICE IDENTIFICATION REGISTER
Address Offset:
Default Value:
Attribute:
Size:
02–03h
04A3h
Read Only
16 bits
This 16-bit register combined with the Vendor Identification Register uniquely identifies any PCI device. Writes
to this register have no effect.
Bits
15:0
40
Description
DEVICE IDENTIFICATION NUMBER: This is a 16 bit value assigned to the PCMC.
82434LX/82434NX
3.2.4 PCICMDÐPCI COMMAND REGISTER
Address Offset:
Default:
Attribute:
Size:
04–05h
06h
Read/Write
16 bits
This 16-bit register provides basic control over the PCMC’s ability to respond to PCI cycles. The PCICMD
Register enables and disables the SERRÝ signal, the parity error signal (PERRÝ), PCMC response to PCI
special cycles, and enables and disables PCI master accesses to main memory.
Bits
Description
15:9
RESERVED
8
SERRÝ ENABLE (SERRE): SERRE enables/disables the SERRÝ signal. When SERRE e 1 and
PERRE e 1, SERRÝ is asserted if the PCMC detects a PCI Bus address/data parity error, or main
memory (DRAM) or cache parity error, and the corresponding errors are enabled in the ErrorCommand Register. When SERRE e 1 and bit 7 in the Error Command Register is set to 1, the PCMC
asserts SERRÝ when it detects a target abort on a PCMC-initiated PCI cycle. When SERRE e 0,
SERRÝ is never asserted.
7
RESERVED
6
PARITY ERROR ENABLE (PERRE): PERRE controls the PCMC’s response to PCI parity errors. This
bit is a master enable for bit 3 of the ERRCMD Register. PERRE works in conjunction with the
SERRE bit to enable SERRÝ assertion when the PCMC detects a PCI bus parity error, or a main
memory or cache parity error.
5:3
RESERVED
2
BUS MASTER ENABLE (BME): The PCMC does not support disabling of its bus master capability on
the PCI Bus. This bit is always set to 1, permitting the PCMC to function as a PCI Bus master. Writes
to this bit position have no affect.
1
MEMORY ACCESS ENABLE (MAE): This bit enables/disables PCI master access to main memory
(DRAM). When MAE e 1, the PCMC permits PCI masters to access main memory if the MEMCSÝ
signal is asserted. When MAE e 0, the PCMC does not respond to PCI master main memory
accesses (MEMCSÝ asserted).
0
I/O ACCESS ENABLE (IOAE): The PCMC does not respond to PCI I/O cycles, hence this command
is not supported. PCI master access to I/O space on the Host Bus is always disabled.
41
82434LX/82434NX
3.2.5 PCISTSÐPCI STATUS REGISTER
Address Offset:
Default Value:
Attribute:
Size:
06–07h
40h
Read Only, Read/Write Clear
16 bits
PCISTS is a 16-bit status register that reports the occurrence of a PCI master abort, PCI target abort, and
DRAM or cache parity error. PCISTS also indicates the DEVSELÝ timing that has been set by the PCMC
hardware. Bits [15:12] are read/write clear and bits [10:9] are read only.
Bits
Attribute
15
Description
RESERVED
14
R/WC
SIGNALED SYSTEM ERROR (SSE): When the PCMC asserts the SERRÝ signal, this bit
is also set to 1. Software sets SSE to 0 by writing a 1 to this bit.
13
R/WC
RECEIVED MASTER ABORT STATUS (RMAS): When the PCMC terminates a Host-toPCI transaction (PCMC is a PCI master), which is not a special cycle, with a master abort,
this bit is set to 1. Software resets this bit to 0 by writing a 1 to it.
12
R/WC
RECEIVED TARGET ABORT STATUS (RTAS): When a PCMC-initiated PCI transaction
is terminated with a target abort, RTAS is set to 1. The PCMC also asserts SERRÝ if the
SERRÝ Target Abort bit in the ERRCMD Register is 1. Software resets RTAS to 0 by
writing a 1 to it.
11
10:9
8
7:0
42
RESERVED
RO
DEVSELÝ TIMING (DEVT): This 2-bit field indicates the timing of the DEVSELÝ signal
when the PCMC responds as a target. The PCI specification defines three allowable
timings for assertion of DEVSELÝ: 00 e fast, 01 e medium, and 10 e slow (DEVT e 11 is
reserved). DEVT indicates the slowest time that a device asserts DEVSELÝ for any bus
command, except configuration read and write cycles. Note that these two bits determine
the slowest time that the PCMC asserts DEVSELÝ. However, the PCMC can also assert
DEVSELÝ in medium time.
The PCMC asserts DEVSELÝ in response to sampling MEMCSÝ asserted. The PCMC
samples MEMCSÝ one and two clocks after FRAMEÝ is asserted. If MEMCSÝ is
asserted one PCI clock after FRAMEÝ is asserted, then the PCMC responds with
DEVSELÝ in slow time.
R/WC
DATA PARITY DETECTED (DPD): This bit is set to 1 when all of the following conditions
are met: 1). The PCMC asserted PERRÝ or sampled PERRÝ asserted. 2). The PCMC
was the bus master for the operation in which the error occurred. 3). The PERRE bit in
the Command Register is set to 1. Software resets DPD to 0 by writing a 1 to it.
RESERVED
82434LX/82434NX
3.2.6 RIDÐREVISION IDENTIFICATION REGISTER
Address Offset:
Default Value:
Attribute:
Size:
08h
03h for A–3 Stepping (82434LX)
01h for A–1 Stepping (82434LX)
10h for A–0 Stepping (82434NX)
11h for A–1 Stepping (82434NX)
Read Only
8 bits
This register contains the revision number of the PCMC. These bits are read only and writes to this register
have no effect. For the A–2 Stepping of the 82434LX, this value is 03h.
For the A–1 Stepping of the 82434NX, this value is 11h.
Bits
Description
7:0
REVISION IDENTIFICATION NUMBER: This is an 8-bit value that indicates the revision identification
number for the PCMC.
3.2.7 RLPIÐREGISTER-LEVEL PROGRAMMING INTERFACE REGISTER
Address Offset:
Default Value:
Attribute:
Size:
09h
00h
Read Only
8 bits
This register defines the PCMC as having no defined register-level programming interface.
Bits
7:0
Description
REGISTER-LEVEL PROGRAMMING INTERFACE (RLPI): The value of 00h defines the PCMC as
having no defined register-level programming interface.
3.2.8 SUBCÐSUB-CLASS CODE REGISTER
Address Offset:
Default Value:
Attribute:
Size:
0Ah
00h
Read Only
8 bits
This register defines the PCMC as a host bridge.
Bits
7:0
Description
SUB-CLASS CODE (SCCD): The value of this register is 00h defining the PCMC as host bridge.
43
82434LX/82434NX
3.2.9 BASECÐBASE CLASS CODE REGISTER
Address Offset:
Default Value:
Attribute:
Size:
0Bh
06h
Read Only
8 bits
This register defines the PCMC as a bridge device.
Bits
7:0
Description
BASE CLASS CODE (BCCD): The value in this register is 06h defining the PCMC as bridge device.
3.2.10 MLTÐMASTER LATENCY TIMER REGISTER
Address Offset:
Default Value:
Attribute:
Size:
0Dh
20h
Read/Write
8 bits
MLT is an 8-bit register that controls the amount of time the PCMC, as a bus master, can burst data on the PCI
Bus. MLT is used when the PCMC becomes the PCI Bus master and is cleared and suspended when the
PCMC is not asserting FRAMEÝ. When the PCMC asserts FRAMEÝ, the counter is enabled and begins
counting. If the PCMC finishes its transaction before the count expires, the MLT count is ignored. If the count
expires before the transaction completes, the PCMC initiates a transaction termination as soon as its GNTÝ is
removed. The number of clocks programmed in the MLT represents the guaranteed time slice (measured in
PCI clocks) allotted to the PCMC, after which it must surrender the bus as soon as its GNTÝ is taken away.
The number of clocks in the Master Latency Timer is the count value field multiplied by 16.
Bits
Description
7:4
MASTER LATENCY TIMER COUNT VALUE: If GNTÝ is negated after the burst cycle is initiated, the
PCMC limits the duration of the burst cycle to the number of PCI Bus clocks specified by this field
multiplied by 16.
3:0
RESERVED
3.2.11 BISTÐBIST REGISTER
Address Offset:
Default Value:
Attribute:
Size:
0Fh
0h
Read Only
8 bits
The BIST function is not supported by the PCMC. Writes to this register have no affect.
Bits
Attribute
Description
7
RO
BIST SUPPORTED: This read only bit is always set to 0, disabling the BIST function.
Writes to this bit position have no affect.
6
RW
START BIST: This function is not supported and writes have no affect.
5:4
3:0
44
RESERVED
RO
COMPLETION CODE: This read only field always returns 0 when read and writes have
no affect.
82434LX/82434NX
3.2.12 HCSÐHOST CPU SELECTION REGISTER
Address Offset:
Default Value:
Access:
Size:
50h
82h (82434LX)
A2h (83434NX)
Read/Write, Read Only
8 bits
The HCS Register is used to specify the Host CPU type and speed. This 8-bit register is also used to enable
and disable the first level cache.
Bits
Access
7:5
RO
Description
HOST CPU TYPE (HCT): This field defines the Host CPU type.
82434LX
These bits are hardwired to 100 which selects the Pentium processor. All other
combinations are reserved.
82434NX
In the 82434NX, these bits are reserved. Reads and writes to these bits have no effect.
4:3
RESERVED
2
R/W
FIRST LEVEL CACHE ENABLE (FLCE): FLCE enables and disables the first level cache.
When FLCE e 1, the PCMC responds to CPU cycles with KENÝ asserted for cacheable
memory cycles. When FLCE e 0, KENÝ is always negated. This prevents new cache line
fills to either the first level or second level caches.
1:0
R/W
HOST OPERATING FREQUENCY (HOF): The DRAM refresh rate is adjusted according to
the frequency selected by this field. For the 82434LX, only bit 0 is used and bit 1 is
reserved.
82434LX
Bit 1 is reserved. If bit 0 is 1, the 82434LX supports a 66 MHz CPU. If bit 0 is 0, the
82434LX supports a 60 MHz CPU.
82434NX
These bits select the Host CPU frequency supported as follows:
Bits [1:0] Host CPU Frequency
00
Reserved
01
50 MHz
10
60 MHz
11
66 MHz
45
82434LX/82434NX
3.2.13 DFCÐDETURBO FREQUENCY CONTROL REGISTER
Address Offset:
Default Value:
Attribute:
Size:
51h
80h
Read/Write
8 bits
Some software packages rely on the operating speed of the processor to time certain system events. To
maintain backward compatibility with these software packages, the PCMC provides a mechanism to emulate a
slower operating speed. This emulation is achieved with the PCMC’s deturbo mode. The deturbo mode is
enabled and disabled via the DM bit in the Turbo-Reset Control Register. When the deturbo mode is enabled,
the PCMC periodically asserts AHOLD to slow down the effective speed of the CPU. The duty cycle of the
AHOLD active period is controlled by the DFC Register.
Bits
Description
7:6
DETURBO MODE FREQUENCY ADJUSTMENT VALUE: This 8-bit value effectively defines the duty
cycle of the AHOLD signal. DFC [7:6] are programmable and DFC [5:0] are 0. The value programmed
into this register is compared against a free running 8-bit counter running at (/8 the CPU clock. When
the counter is greater than the value specified in this register, AHOLD is asserted. AHOLD is negated
when the counter value is equal to or smaller than the contents of this register. AHOLD is negated
when the counter rolls over to 00h. The deturbo emulation speed is directly proportional to the value
in this register. Smaller values in this register yield slower deturbo emulation speed. The value of 00h
is reserved.
5:0
RESERVED
3.2.14 SCCÐSECONDARY CACHE CONTROL REGISTER
Address Offset:
Default Value:
Attribute:
Size:
52h
SSS01R10 (82434LX)
SSS01010 (82434NX)
(S e Strapping option)
Read/Write
8 bits
This 8-bit register defines the secondary cache operations. The SCC Register enables and disables the
second level cache, adjusts cache size, selects the cache write policy, and defines the cache SRAM type.
After hard reset, SCC [7:5] contain the opposite of the signal levels sampled on the Host address lines
A [31:29] .
Bits
7:6
Description
SECONDARY CACHE SIZE (SCS): This field defines the size of the second level cache. The values
sampled on the A [31:30] lines at the rising edge of the PWROK signal are inverted and stored in this
field.
Bits [7:6]
00
01
10
11
46
Secondary Cache Size
Cache not populated
Reserved
256-KBytes
512-KBytes
82434LX/82434NX
Bits
Description
5
SRAM TYPE (SRAMT): This bit selects between standard SRAMs or burst SRAMS to implement the
second level cache. When SRAMT e 0, standard SRAMs are selected. When SRAMT e 1, burst
SRAMs are selected. This bit reflects the signal level on the A29 pin at the rising edge of the PWROK
signal. This value can be overwritten with subsequent writes to the SCC Register.
4
82434LX: SECONDARY CACHE ALLOCATION (SCA): SCA controls when the PCMC performs line
fills in the second level cache. When SCA is set to 0, only CPU reads of cacheable main memory with
CACHEÝ asserted are cached in the second level cache. When SCA is set to 1, all CPU reads of
cacheable main memory are cached in the second level cache.
3
CACHE BYTE CONTROL (CBC): When programmed for asynchronous SRAMs, this bit defines
whether the cache uses individual write enables per byte or has a single write enable and byte select
lines per byte. When CBC is set to 1, write enable control is used. When CBC is set to 0, byte select
control is used.
2
82434LX: RESERVED
82434NX: SRAM CONNECTIVITY (SRAMC): This bit enables different connectivities for the second
level cache. When SRAMC is set to 0, the second level cache is in 82434LX compatible mode and all
connections between the PCMC and second level cache SRAMs are the same as the 82434LX.
When asynchronous SRAMs are used, setting this bit to 1 enables the CCS [1:0] Ý functionality.
CCS [1:0] Ý are used with asynchronous SRAMs to de-select the SRAMs, placing them in a low
power standby mode. When the CPU runs a halt or stop grant special cycle, the 82434NX negates
CCS [1:0] Ý, placing the second level cache in a power saving mode. The PCMC then asserts
CCS [1:0] Ý (activating the SRAMs) when the CPU asserts ADSÝ. When using burst SRAMs, setting
this bit to 1 enables the CCS1Ý functionality and indicates to the PCMC that no external address
latch is present.
1
82434LX: SECONDARY CACHE WRITE POLICY (SCWP): SCWP selects between write-back and
write-through cache policies for the second level cache. When SCWP e 0 and the second level cache
is enabled (bit 0 e 1), the second level cache is configured for write-through mode. When SCWP e 1
and the second level cache is enabled (bit 0 e 1), the second level cache is configured for write-back
mode.
82434NX: RESERVED: Secondary cache write-through mode is not supported. The secondary cache
is always in write-back mode and this bit has no affect. SCWP can be set to 0, however, the 82434NX
will still operate the secondary cache in write-back mode.
0
SECONDARY CACHE ENABLE (SCE): SCE enables and disables the secondary cache. When
SCE e 1, the secondary cache is enabled. When SCE e 0, the secondary cache is disabled. When the
secondary cache is disabled, the PCMC forwards all main memory cycles to the DRAM interface.
Note that setting this bit to 0 does not affect existing valid cache lines. If a cache line contains
modified data, the data is not written back to memory. Valid lines in the cache remain valid. When the
secondary cache is disabled, the CWE [7:0] Ý lines remain negated. COE [1:0] Ý may still toggle.
When system software disables secondary caching through this register during run-time, the software
should first flush the second level cache. This process is accomplished by first disabling first level
caching via the PCE bit in the HCS Register. This prevents the KENÝ signal from being asserted,
which disables any further line fills. At this point, software executes the WBINVD instruction to flush
the caches. When the instruction completes, bit 0 of this register can be reset to 0, disabling the
secondary cache. The first level cache can then be enabled by writing the PCE bit in the HCS
Register.
47
82434LX/82434NX
3.2.15 HBCÐHOST READ/WRITE BUFFER CONTROL
Address Offset:
Default Value:
Attribute:
Size:
53h
00h
Read/Write
8 bits
The HBC Register enables and disables Host-to-main memory and Host-to-PCI posting of write cycles. When
posting is enabled, the write buffers in the LBX devices post the data that is destined for either main memory
or PCI. This register also permits a CPU-to-main memory read cycle to be performed before any pending
posted write data is written to memory.
Bits
Description
7:4
RESERVED
3
READ-AROUND-WRITE ENABLE (RAWCM): If enabled, the PCMC, during a CPU read cycle to
memory where posted write cycles are pending, internally snoops the write buffers. If the address of
the read differs from the posted write addresses, the PCMC initiates the memory read cycle ahead of
the pending posted memory write. When RAWCM e 0, the pending posted write is written to memory
before the memory read is performed. When RAWCM e 1, the PCMC initiates the memory read ahead
of the pending posted memory writes.
2
RESERVED
1
HOST-TO-PCI POSTING ENABLE (HPPE): This bit enables/disables the posting of Host-to-PCI
write data in the LBX posting buffers. When HPPE e 1, up to 4 Dwords of data can be posted to PCI.
HPPE e 0 is reserved. Buffering is disabled and each CPU write does not complete until the PCI
transaction completes (TRDYÝ is asserted).
0
82434LX: HOST-TO-MEMORY POSTING ENABLE (HMPE): This bit enables/disables the posting of
Host-to-main memory write data in the LBX buffers. When HMPE e 1, the CPU can post a single write
or a burst write (4 Qwords). The CPU burst write completes at 4-1-1-1 when the second level cache is
in write-back mode and at 3-1-1-1 when the second level cache is either disabled or in write-through
mode. When HMPE e 0, Host-to-main memory posting is disabled and the CPU write cycles do not
complete until the data is written to memory.
82434NX: RESERVED: For the 82434NX, posting is always enabled and this bit has no affect. The
CPU can post a single write or burst write (4 Qwords). HMPE can be set to 0, however, the 82434NX
will still allow posting of CPU-to-main memory writes.
48
82434LX/82434NX
3.2.16 PBCÐPCI READ/WRITE BUFFER CONTROL REGISTER
Address Offset:
Default Value:
Attribute:
Size:
54h
00h
Read/Write
8 bits
The PBC Register enables and disables PCI-to-main memory write posting and permits single CPU-to-PCI
writes to be assembled into PCI burst cycles.
Bits
Description
7:3
RESERVED
2
LBXs CONNECTED TO TRDYÝ: The TRDYÝ pin on the LBXs can be connected either to the PCI
TRDYÝ signal or to ground. The cycle time for CPU-to-PCI writes is improved if TRDYÝ is connected
to the LBXs. Since there are two LBXs used in a system, connecting this signal to the LBXs increases
the electrical loading of TRDYÝ by two loads. When the LBXs are externally hard-wired to TRDYÝ,
this bit should be set to 1. Note that this should be done prior to the first Host-to-PCI write or data
corruption will occur. Setting this bit to 1 enables the capability of CPU-to-PCI writes at 2-1-1-1 . . .
(PCI clocks). When this bit is 0, the LBXs are not connected to TRDYÝ and CPU-to-PCI writes are
completed at 2-2-2-2 . . . timing.
1
PCI BURST WRITE ENABLE (PBWE): This bit enables and disables PCI Burst memory write cycles
for back-to-back sequential CPU memory write cycles to PCI. When PBWE is set to 1, PCI burst
writes are enabled. When PBWE is reset to 0, PCI burst writes are disabled and each single CPU write
to PCI invokes a single PCI write cycle (each cycle has an associated FRAMEÝ sequence).
0
PCI-TO-MEMORY POSTING ENABLE (PMPE): This bit enables and disables posting of PCI-tomemory write cycles. The posting occurs in a pair of four Dword-deep buffers in the LBXs. When
PMPE is set to 1, these buffers are used to post PCI-to-main memory write data. When PMPE is reset
to 0, PCI write transactions to main memory are limited to single transfers. The PCMC asserts
STOPÝ with the first TRDYÝ to disconnect the PCI Master.
49
82434LX/82434NX
3.2.17 DRAMCÐDRAM CONTROL REGISTER
Address Offset:
Default Value:
Attribute:
Size:
57h
31h
Read/Write
8 bits
This 8-bit register controls main memory DRAM operating modes and features.
Bits
7:6
Description
82434LX: RESERVED
82434NX: DRAM BURST TIMING (DBT): The DRAM interface can be configured for 3 different burst
timings. The CASÝ pulse width for X-3-3-3 timing is one clock shorter than the CASÝ pulse width for
X-4-4-4 timing.
Bits [7:6] Burst Timing
00
X-4-4-4 Read/Write timing (default)
01
X-4-4-4 Read, X-3-3-3 Write timing
10
Reserved
11
X-3-3-3 Read/Write timing
5
PARITY ERROR MASK (PERRM): When PERRM e 1, parity errors generated during DRAM read
cycles initiated by either the CPU request or a PCI Master are masked. This bit affects bits 0 and 1 of
the Error Command Register and the ability of the PCMC to respond to PCHKÝ and assert SERRÝ
when a DRAM parity error occurs. When PERRM is reset to 0, parity errors are not masked.
4
0-ACTIVE RASÝ MODE: This bit determines if the DRAM page for a particular row remains open (i.e.
RASÝ remains asserted after a DRAM cycle) enabling the possibility that the next DRAM access may
be either a page hit, a page miss, or a row miss. The DRAM interface is then in 1-active RASÝ mode.
If this bit is reset to 0, RASÝ remains asserted after a DRAM cycle. If this bit is set to 1, RASÝ is
negated after every DRAM cycle, resulting in a row miss for every DRAM cycle. The DRAM interface
is then in 0-active RASÝ mode.
3
SMRAM ENABLE (SMRE): When SMRE e 1, CPU accesses to SMM space are qualified with the
SMIACTÝ pin of the CPU. The location of this space is determined by the SBS field of the SMRAM
Register. Read and write cycles to SMM space function normally if SMIACTÝ is asserted. If
SMIACTÝ is negated when accessing this space, the cycle is forwarded to PCI. When SMRE e 0,
accesses to SMM space are treated normally and SMIACTÝ has no effect. SMRE must be set to 1 to
enable the use of the SMRAM Register at configuration space offset 72h.
2
BURST OF FOUR REFRESH (BFR): When BFR is set to 1, refreshes are performed in sets of four, at
a frequency (/4 of the normal refresh rate. The PCMC defers refreshes to idle times, if possible. When
BFR is reset to 0, single refreshes occur at 15.6 ms refresh rate.
1
82434LX: REFRESH TYPE (RT): When RT e 1, the PCMC uses CASÝ-before-RASÝ timing to
refresh the DRAM array. For this refresh type, the PCMC does not supply refresh addresses. When
RT e 0, RASÝ Only refresh is used and the PCMC drives refresh addresses on the MA [10:0] lines.
RASÝ only refresh can be used with any type of second level cache configuration (i.e., no second
level cache is present, or either a burst SRAM or standard SRAM second level cache is
implemented). CASÝ-before-RASÝ refresh should not be used when a standard SRAM second level
cache is implemented.
82434NX: REFRESH TYPE (RT): In addition to above, when RT e 0, RASÝ only refresh is used and
the PCMC drives refresh addresses on the MA [11:0] lines. Also, CASÝ-before-RASÝ refresh can be
used with a standrad SRAM second level cache.
0
REFRESH ENABLE (RE): When RE is set to 1, the main memory array is refreshed as configured via
bits 1 and 2 of this register. When RE is reset to 0, DRAM refresh is disabled. Note that disabling
refresh results in the loss of DRAM data.
50
82434LX/82434NX
3.2.18 DRAMTÐDRAM TIMING REGISTER
Address Offset:
Default Value:
Attribute:
Size:
58h
00h
Read/Write
8 bits
For the 82434LX, this register controls the leadoff latency for CPU DRAM accesses.
For the 82434NX, this register provides additional control over DRAM timings. One additional wait-state can
be independently added before the assertion of RASÝ, the assertion of the first CASÝ, or both. This is to
allow more flexibility in the layout of the motherboard and in the selection of DRAM speed grades.
Bits
Description
7:2
RESERVED
1
82434LX: RESERVED
82434NX: RASÝ WAIT-STATE (RWS): When RWS e 1, one additional wait state will be inserted
before RASÝ is asserted for row misses or page misses in 1-Active RAS mode and all cycles in
0-Active RAS mode. This provides additional MA [11:0] setup time to RASÝ assertion.
0
CASÝ WAIT-STATE (CWS): When CWS e 1, one additional wait state will be inserted before the first
assertion of CASÝ within a burst cycle. There is no additional delay between CASÝ assertions. This
provides additional MA [11:0] setup time to CASÝ assertion. The CWS bit is typically reset to 0 for
60 MHz operation and set to 1 for 66 MHz operation.
3.2.19 PAMÐPROGRAMMABLE ATTRIBUTE MAP REGISTERS (PAM [6:0] )
Address Offset:
Default Value:
Attribute:
59–5Fh
PAM0 e 0Fh, PAM [1:6] e 00h
Read/Write
The PCMC allows programmable memory and cacheability attributes on 14 memory segments of various sizes
in the 512 KByte–1 MByte address range. Seven Programmable Attribute Map (PAM) Registers are used to
support these features. Three bits are used to specify cacheability and memory attributes for each memory
segment. These attributes are:
RE:
Read Enable. When RE e 1, the CPU read accesses to the corresponding memory segment are directed to main memory. Conversely, when RE e 0, the CPU read accesses are directed to PCI.
WE: Write Enable. When WE e 1, the CPU write accesses to the corresponding memory segment are
directed to main memory. Conversely, when WE e 0, the CPU write accesses are directed to PCI.
CE:
Cache Enable. When CE e 1, the corresponding memory segment is cacheable. CE must not be set to
1 when RE is reset to 0 for any particular memory segment. When CE e 1 and WE e 0, the corresponding memory segment is cached in the first and second level caches only on CPU coded read cycles.
The RE and WE attributes permit a memory segment to be Read Only, Write Only, Read/Write, or disabled.
For example, if a memory segment has RE e 1 and WE e 0, the segment is Read Only. The characteristics for
memory segments with these read/write attributes are described in Table 2.
51
82434LX/82434NX
Table 2. Attribute Definition
Read/Write
Attribute
Read Only
Definition
Read cycles: CPU cycles are serviced by the DRAM in a normal manner.
Write cycles: CPU initiated write cycles are ignored by the DRAM interface as well as the
cache. Instead, the cycles are passed to PCI for termination.
Areas marked as Read Only are cacheable for Code accesses only. These regions may be
cached in the second level cache, however as noted above, writes are forwarded to PCI,
effectively write protecting the data.
Write Only
Read cycles: All read cycles are ignored by the DRAM interface as well as the second level
cache. CPU-initiated read cycles are passed onto PCI for termination. The write only state
can be used while copying the contents of a ROM, accessible on PCI, to main memory for
shadowing, as in the case of BIOS shadowing.
Write cycles: CPU write cycles are serviced by the DRAM and cache in a normal manner.
Read/Write
This is the normal operating mode of main memory. Both read and write cycles from the CPU
and PCI are serviced by the DRAM and cache interface.
Disabled
All read and write cycles to this area are ignored by the DRAM and cache interface. These
cycles are forwarded to PCI for termination.
Each PAM Register controls two regions, typically 16-KByte in size. Each of these regions have a 4-bit field.
The four bits that control each region have the same encoding and are defined in Table 3.
Table 3. Attribute Bit Assignment
Bits [7,3]
Reserved
Bits [6,2]
Cache Enable
Bits [5,1]
Write Enable
Bits [4,0]
Read Enable
x
x
0
0
DRAM Disabled, Accesses Directed to PCI
x
0
0
1
Read Only, DRAM Write Protected, NonCacheable
x
1
0
1
Read Only, DRAM Write Protected,
Cacheable for Code Accesses Only
x
0
1
0
Write Only
x
0
1
1
Read/Write, Non-Cacheable
x
1
1
1
Read/Write, Cacheable
Description
NOTE:
To enable PCI master access to the DRAM address space from C0000h to FFFFFh the MEMCSÝ configuration registers of
the ISA or EISA bridge must be properly configured. These registers must correspond to the PAM Registers in the PCMC.
As an example, consider a BIOS that is implemented on the expansion bus. During the initialization process
the BIOS can be shadowed in main memory to increase the system performance. When a BIOS is shadowed
in main memory, it should be copied to the same address location. To shadow the BIOS, the attributes for that
address range should be set to write only. The BIOS is shadowed by first doing a read of that address. This
read is forwarded to the expansion bus. The CPU then does a write of the same address, which is directed to
main memory. After the BIOS is shadowed, the attributes for that memory area are set to read only so that all
writes are forwarded to the expansion bus.
52
82434LX/82434NX
Table 4. PAM Registers and Associated Memory Segments
PAM Reg
Attribute Bits
Memory Segment
PAM0 [3:0]
R
CE
WE
RE
PAM0 [7:4]
R
CE
WE
PAM1 [3:0]
R
CE
WE
PAM1 [7:4]
R
CE
WE
PAM2 [3:0]
R
CE
WE
PAM2 [7:4]
R
CE
PAM3[3:0]
R
CE
PAM3 [7:4]
R
PAM4[3:0]
R
PAM4 [7:4]
PAM5 [3:0]
Comments
Offset
080000h – 09FFFFh
512K – 640K
59h
RE
0F0000h – 0FFFFFh
BIOS Area
59h
RE
0C0000h – 0C3FFFh
ISA Add-on BIOS
5Ah
RE
0C4000h – 0C7FFFh
ISA Add-on BIOS
5Ah
RE
0C8000h – 0CBFFFh
ISA Add-on BIOS
5Bh
WE
RE
0CC000h – 0CFFFFh
ISA Add-on BIOS
5Bh
WE
RE
0D0000h – 0D3FFFh
ISA Add-on BIOS
5Ch
CE
WE
RE
0D4000h – 0D7FFFh
ISA Add-on BIOS
5Ch
CE
WE
RE
0D8000h – 0DBFFFh
ISA Add-on BIOS
5Dh
R
CE
WE
RE
0DC000h – 0DFFFFh
ISA Add-on BIOS
5Dh
R
CE
WE
RE
0E0000h – 0E3FFFh
BIOS Extension
5Eh
PAM5 [7:4]
R
CE
WE
RE
0E4000h – 0E7FFFh
BIOS Extension
5Eh
PAM6 [3:0]
R
CE
WE
RE
0E8000h – 0EBFFFh
BIOS Extension
5Fh
PAM6 [7:4]
R
CE
WE
RE
0EC000h – 0EFFFFh
BIOS Extension
5Fh
DOS Application Area (00000h-9FFFh)
The 640-KByte DOS application area is split into two regions. The first region is 0 – 512-KByte and the second
region is 512–640 KByte. Read, write, and cacheability attributes are always enabled and are not programmable for the 0–512 KByte region.
Video Buffer Area (A0000h-BFFFFh)
This 128-KByte area is not controlled by attribute bits. CPU-initiated cycles in this region are always forwarded
to PCI for termination. This area is not cacheable.
Expansion Area (C0000h-DFFFFh)
This 128-KByte area is divided into eight 16-KByte segments. Each segment can be assigned one of four
Read/Write states: read-only, write-only, read/write, or disabled Memory that is disabled is not remapped.
Cacheability status can also be specified for each segment.
Extended System BIOS Area (E0000h-EFFFFh)
This 64-KByte area is divided into four 16-KByte segments. Each segment can be assigned independent
cacheability, read, and write attributes. Memory segments that are disabled are not remapped elsewhere.
53
82434LX/82434NX
System BIOS Area (F0000h-FFFFFh)
This area is a single 64-KByte segment. This segment can be assigned cacheability, read, and write attributes.
When disabled, this segment is not remapped.
Extended Memory Area (100000h-FFFFFFFFh)
The extended memory area can be split into several parts:
#
#
#
#
#
Flash BIOS area from 4 GByte to 4 GByte– 512-KByte (aliased on ISA at 16 MBytes – 15.5 MBytes)
DRAM Memory from 1 MByte to a maximum of 192 MBytes
PCI Memory space from the top of DRAM to 4 GByte – 512-KByte
Memory Space Gap between the range of 1 MByte up to 15.5 MBytes
Frame Buffer Range mapped into PCI Memory Space or the Memory Space Gap.
On power-up or reset the CPU vectors to the Flash BIOS area, mapped in the range of 4 GByte to 4 GByte –
512-KByte. This area is physically mapped on the expansion bus. Since these addresses are in the upper
4 GByte range, the request is directed to PCI.
The DRAM memory space can occupy extended memory from a minimum of 2 MBytes up to 192 MBytes. This
memory is cacheable.
The address space on PCI between the Flash BIOS (4 GByte to 4 GByte – 512 KByte) and the top of DRAM
(including any remapped memory) may be occupied by PCI memory. This memory space is not cacheable.
3.2.20 DRBÐDRAM ROW BOUNDARY REGISTERS
Address Offset:
Default Value:
Attribute:
Size:
60–65h (82434LX)
60–67h (82434NX)
02h
Read/Write
8 bits
Note the address offset for each DRB Register is DRB0 e 60h, DRB1 e 61h, DRB2 e 62h, DRB3 e 63h,
DRB4 e 64h, DRB5 e 65h, DRB6 e 66h, and DRB7 e 67h.
3.2.20.1 82434LX Description
The PCMC supports 6 rows of DRAM. Each row is 64 bits wide. The DRAM Row Boundary Registers define
upper and lower addresses for each DRAM row. Contents of these 8-bit registers represent the boundary
addresses in MBytes.
DRB0
DRB1
DRB2
DRB3
DRB4
DRB5
e
e
e
e
e
e
Total
Total
Total
Total
Total
Total
amount
amount
amount
amount
amount
amount
of
of
of
of
of
of
memory
memory
memory
memory
memory
memory
in
in
in
in
in
in
row
row
row
row
row
row
0
0
0
0
0
0
(in MBytes)
a row 1 (in MBytes)
a row 1 a row 2 (in MBytes)
a row 1 a row 2 a row 3 (in MBytes)
a row 1 a row 2 a row 3 a row 4 (in MBytes)
a row 1 a row 2 a row 3 a row 4 a row 5 (in MBytes)
The DRAM array can be configured with 256K x 36, 1M x 36 and 4M x 36 SIMMs. Each register defines an
address range that will cause a particular RASÝ line to be asserted (e.g. if the first DRAM row is 2 MBytes in
size then accesses within the 0 MByte–2 MBytes range will cause RAS0Ý to be asserted). The DRAM Row
54
82434LX/82434NX
Boundary (DRB) Registers are programmed with an 8-bit upper address limit value. This upper address limit is
compared to A [27:20] of the Host address bus, for each row, to determine if DRAM is being targeted. Since
this value is 8 bits and the resolution is 1 MByte, the total bits compared span a 256 MByte space. However,
only 192 MBytes of main memory is supported.
Bits
7:0
Description
ROW BOUNDARY ADDRESS IN MBYTES: This 8-bit value is compared against address lines
A [27:20] to determine the upper address limit of a particular row, i.e. DRB b previous DRB e row
size.
Row Boundary Address in MBytes
These 8-bit values represent the upper address limits of the six rows (i.e., this row - previous row e row size).
Unpopulated rows have a value equal to the previous row (row size e 0). The value programmed into DRB5
reflects the maximum amount of DRAM in the system. Memory remapped at the top of DRAM, as a result of
setting the Memory Space Gap Register, is not reflected in the DRB Registers. The top of memory is always
determined by the value written into DRB5 added to the memory space gap size (if enabled).
As an example of a general purpose configuration where 3 physical rows are configured for either single-sided
or double-sided SIMMs, the memory array would be configured like the one shown in Figure 8. In this configuration, the PCMC drives two RASÝ signals directly to the SIMM rows. If single-sided SIMMs are populated, the
even RASÝ signal is used and the odd RASÝ is not connected. If double-sided SIMMs are used, both RASÝ
signals are used.
290479 – 9
Figure 8. SIMMs and Corresponding DRB Registers
The following 2 examples describe how the DRB Registers are programmed for cases of single-sided and
double-sided SIMMs on a motherboard having a total of 6 SIMM sockets.
55
82434LX/82434NX
Example Ý1
The memory array is populated with six single-sided 256-KByte x 36 SIMMs. Two SIMMs are required for each
populated row making each populated row 2 MBytes in size. Filling the array yields 6 MBytes total DRAM. The
DRB Registers are programmed as follows:
DRB0
DRB1
DRB2
DRB3
DRB4
DRB5
e
e
e
e
e
e
02h
02h
04h
04h
06h
06h
populated
empty row, not double-sided SIMMs
populated
empty row, not double-sided SIMMs
populated
empty row, not double-sided SIMMs, maximum memory e 6 MBytes.
Example Ý2
As an another example, if the first four SIMM sockets are populated with 2 MBytes x 36 double-sided SIMMs
and the last two SIMM sockets are populated with 4 MBytes x 36 single-sided SIMMs then filling the array
yields 64 MBytes total DRAM. The DRB Registers are programmed as follows:
DRB0 e 08h populated with 8 MBytes, (/2 of the double-sided SIMMs
DRB1 e 10h the other 8 MBytes of the double-sided SIMMs
DRB2 e 18h populated with 8 MBytes, (/2 of the double-sided SIMMs
DRB3 e 20h the other 8 MBytes of the double-sided SIMMs
DRB4 e 40h populated with 32 MBytes
DRB5 e 40h empty row, not double-sided SIMMs, maximum memory e 64 MBytes.
3.2.20.2 82434NX Description
The PCMC supports 8 rows of DRAM. Each row is 64 bits wide. The DRAM Row Boundary Registers define
upper and lower addresses for each DRAM row. Contents of these 8-bit registers are concatenated with the
associated nibble of the DRBE Register to form 12 bit quantities that represent the row boundary addresses in
MBytes.
DRBE [3:0] l l DRB0 e
Total amount of memory in row 0 (in MBytes)
Total amount of memory in row 0 a row 1 (in MBytes)
DRBE [7:4] l l DRB1 e
DRBE [11:8] l l DRB2 e
Total amount of memory in row 0 a row 1 a row 2 (in MBytes)
DRBE [15:12] l l DRB3 e Total amount of memory in row 0 a row 1 a row 2 a row 3 (in MBytes)
DRBE [19:16] l l DRB4 e Total amount of memory in row 0 a row 1 a row 2 a row 3 a row 4 (in MBytes)
DRBE [23:20] l l DRB5 e Total amount of memory in row 0 a row 1 a row 2 a row 3 a row 4 a row 5 (in
Bytes)
DRBE [27:24] l l DRB6 e Total amount of memory in row 0 a row 1 a row 2 a row 3 a row 4 a row 5 a
row 6 (in MBytes)
DRBE [31:28] l l DRB7 e Total amount of memory in row 0 a row 1 a row 2 a row 3 a row 4 a row 5 a
row 6 a row 7 (in MBytes)
The DRAM array can be configured with 256K x 36, 1M x 36, 4M x 36, and 16M x 36 SIMMs. Each register
defines an address range that will cause a particular RASÝ line to be asserted (e.g. if the first DRAM row is
2 MBytes in size then accesses within the 0 to 2 MBytes range will cause RAS0Ý to be asserted). The DRAM
Row Boundary (DRB) Registers are programmed with an 8-bit upper address limit value. The DRBE Register
extends the programming model of this mechanism to 12 bits, however only 10 bits are implemented at this
time. This upper address limit is compared to A [29:20] of the Host address bus, for each row, to determine if
DRAM is being targeted. Since this value is 10 bits and the resolution is 1 MByte, the total bits compared span
a 1 GByte space. However, other resource limits in the PCMC cap the total usable DRAM space at
512 MBytes.
56
82434LX/82434NX
Bits
7:0
Description
ROW BOUNDARY ADDRESS IN MBYTES: This 8-bit value is concatenated with a nibble from the
DRBE Register and then compared against address lines A [29:20] to determine the upper address
limit of a particular row (i.e. DRB b previous DRB e row size).
Row Boundary Address in MBytes
These 10-bit values represent the upper address limits of the 8 rows (i.e., this row - previous row e row size).
Unpopulated rows have a value equal to the previous row (row size e 0). The value programmed into
DRBE [31:28] ll DRB7 reflects the maximum amount of DRAM in the system. Memory remapped at the top of
DRAM, as a result of setting the Memory Space Gap Register, is not reflected in the DRB Registers. The top of
memory is determined by the value written into DRBE [31:28] ll DRB7 added to the memory space gap size (if
enabled). If DRBE[31:28] ll DRB7 plus the memory space gap is greater than 512 MBytes then 512 MBytes of
DRAM are available.
The following 2 examples describe how the DRB Registers are programmed for cases of single-sided and
double-sided SIMMs on a motherboard having a total of 8 SIMM sockets.
Example Ý1
The memory array is populated with eight single-sided 256-KByte x 36 SIMMs. Two SIMMs are required for
each populated row making each populated row 2 MBytes in size. Filling the array yields 8 MBytes total DRAM.
The DRB Registers are programmed as follows:
DRBE [3:0] e 0h
DRB0 e 02h populated
DRBE [7:4] e 0h
DRB1 e 02h empty row, not double-sided SIMMs
DRB2 e 04h populated
DRBE [11:8] e 0h
DRBE [15:12] e 0h DRB3 e 04h empty row, not double-sided SIMMs
DRBE [19:16] e 0h DRB4 e 06h populated
DRBE [23:20] e 0h DRB5 e 06h empty row, not double-sided SIMMs
DRBE [27:24] e 0h DRB6 e 08h populated
DRBE [31:28] e 0h DRB7 e 08h empty row, not double-sided SIMMs, max memory e 8 MBytes.
Example Ý2
As an another example, if the first four SIMM sockets are populated with 2 MByte x 36 double-sided SIMMs
and the last four SIMM sockets are populated with 16 MByte x 36 single-sided SIMMs then filling the array
yields 288 MBytes total DRAM. The DRB Registers are programmed as follows:
DRBE [3:0] e 0h
DRB0 e 08h populated with 8 MBytes, (/2 of double-sided SIMMs
DRBE [7:4] e 0h
DRB1 e 10h the other 8 MBytes of the double-sided SIMMs
DRB2 e 18h populated with 8 MBytes, (/2 of double-sided SIMMs
DRBE [11:8] e 0h
DRBE [15:12] e 0h DRB3 e 20h the other 8 MBytes of the double-sided SIMMs
DRBE [19:16] e 0h DRB4 e A0h populated with 128 MBytes
DRBE [23:20] e 0h DRB5 e A0h empty row, not double-sided SIMMs
DRBE [27:24] e 1h DRB6 e 20h populated with 128 MBytes
DRBE [31:28] e 1h DRB7 e 20h empty row, not double-sided SIMMs, max memory e 288 MBytes.
57
82434LX/82434NX
3.2.21 DRBEÐDRAM ROW BOUNDARY EXTENSION REGISTER
Address Offset:
Default Value:
Attribute:
Size:
68-6Bh
0000h
Read/Write
32 bits
The DRBE Register is not implemented in the 82434LX. This register contains an extension for each of the
DRAM Row Boundary (DRB) Registers. Each nibble of the DRBE Register is concatenated with a DRB
Register (see DRB Register section for details on the use of the DRB and DRBE Registers).
290479 – 10
Bits
31:0
Description
EXTENSIONS FOR DRB0 THROUGH DRB7: Each nibble corresponds to a DRB. The nibble of the
DRBE and its corresponding DRB are concatenated and used to indicate the boundaries between
rows of DRAM.
3.2.22 ERRCMDÐERROR COMMAND REGISTER
Address Offset:
Default Value:
Attribute:
Size:
70h
00h
Read/Write
8 bits
The Error Command Register controls the PCMC responses to various system errors. Bit 6 of the PCICMD
Register is the master enable for bit 3 of this register. Bit 6 of the PCICMD Register must be set to 1 to enable
the error reporting function defined by bit 3 of this register. Bits 6 and 8 of the PCICMD Register are the master
enables for bits 7, 6, 5, 4, and 1 of this register. Both bits 6 and 8 of the PCICMD Register must be set to 1 to
enable the error reporting functions defined by bits 7, 6, 5, 4, and 1 of this register.
58
82434LX/82434NX
Bits
Description
7
SERRÝ ON RECEIVED TARGET ABORT: When this bit is set to 1 (and bit 8 of the PCICMD
Register is 1), the PCMC asserts SERRÝ upon receiving a target abort. When this bit is set to 0, the
PCMC is disabled from asserting SERRÝ upon receiving a target abort.
6
SERRÝ ON TRANSMITTED PCI DATA PARITY ERROR: When this bit is set to 1 (and bits 6 and 8
of the PCICMD Register are both 1), the PCMC asserts SERRÝ when it detects a data parity error as
a result of a CPU-to-PCI write (PERRÝ detected asserted). When this bit is set to 0, the PCMC is
disabled from asserting SERRÝ when data parity errors are detected via PERRÝ.
5
82434LX: RESERVED
82434NX: SERRÝ ON RECEIVED PCI DATA PARITY ERROR: When this bit is set to 1 (and bits 6
and 8 of the PCICMD Register are both 1), the PCMC asserts SERRÝ when it detects a data parity
error as a result of a CPU-to-PCI read (PAR incorrect with received data). In this case, the SERRÝ
signal is asserted when parity errors are detected on PCI return data. When this bit is set to 0, the
PCMC is disabled from asserting SERRÝ when data parity errors are detected during a CPU-to-PCI
read.
4
82434LX: RESERVED
82434NX: SERRÝ ON PCI ADDRESS PARITY ERROR: When this bit is set to 1 (and bits 6 and 8 of
the PCICMD Register are both 1), the PCMC asserts SERRÝ when it detects an address parity error
on PCI transactions. When this bit is set to 0, the PCMC is disabled from asserting SERRÝ when
address parity errors are detected on PCI transactions.
3
82434LX: RESERVED
82434NX: PERRÝ ON RECEIVING A DATA PARITY ERROR: This bit indicates whether the
PERRÝ signal is implemented in the system. When this bit is set to 1 (and bit 6 of the PCICMD
Register is 1), the PCMC asserts PERRÝ when it detects a data parity error (PAR incorrect with
received data), either from a CPU-to-PCI read or a PCI master write to memory. When this bit is set to
0 (or bit 6 of the PCICMD Register is set to 0), the PERRÝ signal is not asserted by the PCMC.
2
L2 CACHE PARITY ENABLE: This bit indicates that the second level cache implements parity. When
this bit is set to 1, bits 0 and 1 of this register control the checking of parity errors during CPU reads
from the second level cache. If this bit is 0, parity is not checked when the CPU reads from the
second level cache (PCHKÝ ignored) and neither bit 1 nor bit 0 apply.
1
SERRÝ ON DRAM/L2 CACHE DATA PARITY ERROR ENABLE: This bit enables/disables the
SERRÝ signal for parity errors on reads from main memory or the second level cache. When this bit
is set to 1 and bit 0 of this register is set to 1 (and bits 6 and 8 of the PCICMD Register are set to 1),
SERRÝ is enabled upon a PCHKÝ assertion from the CPU when reading from main memory or the
second level cache. The processor indicates that a parity error was received by asserting PCHKÝ.
The PCMC then latches status information in the Error Status Register and asserts SERRÝ. When
this bit is 0, SERRÝ is not asserted upon detecting a parity error. Bits [1:0] e 10 is a reserved
combination.
0 e Disable assertion of SERRÝ upon detecting a DRAM/second level cache read parity error.
1 e Enable assertion of SERRÝ upon detecting a DRAM/second level cache read parity error.
0
MCHK ON DRAM/L2 CACHE DATA PARITY ERROR ENABLE: When this bit is set to 1, PENÝ is
asserted for data returned from main memory or the second level cache. The processor indicates
that a parity error was received by asserting the PCHKÝ signal. In addition, the processor invokes a
machine check exception, if enabled via the MCE bit in CR4 in the Pentium processor. The PCMC
then latches status information in the Error Status register. When this bit is 0, PENÝ is not asserted.
Bits [1:0] e 10 is a reserved combination.
59
82434LX/82434NX
3.2.23 ERRSTSÐERROR STATUS REGISTER
Address Offset:
Default Value:
Attribute:
Size:
71h
00h
Read/Write Clear
8 bits
The Error Status Register is an 8-bit register that reports the occurrence of PCI, second level cache, and
DRAM parity errors. This register also reports the occurrence of a CPU shutdown cycle.
Bits
Description
7
RESERVED
6
PCI TRANSMITTED DATA PARITY ERROR: The PCMC sets this bit to a 1 when it detects a data
parity error (PERRÝ asserted) as a result of a CPU-to-PCI write. Software resets this bit to 0 by
writing a 1 to it.
5
82434LX: RESERVED
82434NX: PCI RECEIVED DATA PARITY ERROR: The PCMC sets this bit to a 1 when it detects a
data parity error (PAR incorrect with received data) as a result of a CPU-to-PCI read. Software resets
this bit to 0 by writing a 1 to it.
4
82434LX: RESERVED
82434NX: PCI ADDRESS PARITY ERROR: The PCMC sets this bit to a 1 when it detects an address
parity error (PAR incorrect with received address and C/BEÝ lines) on a PCI master transaction.
Software resets this bit to 0 by writing a 1 to it.
3
MAIN MEMORY DATA PARITY ERROR: The PCMC sets this bit to a 1 when it detects a parity error
from the CPU PCHKÝ signal resulting from a CPU-to-main memory read. Software resets this bit to 0
by writing a 1 to it.
2
L2 CACHE DATA PARITY ERROR: The PCMC sets this bit to a 1 when it detects a parity error from
the CPU PCHKÝ signal resulting from a CPU read access that hit in the second level cache. Software
resets this bit to 0 by writing a 1 to it.
1
RESERVED
0
SHUTDOWN CYCLE DETECTED: The PCMC sets this bit to a 1 when it detects a shutdown special
cycle on the Host Bus. Under this condition the PCMC drives a shutdown special cycle on PCI and
asserts INIT. Software resets this bit to 0 by writing a 1 to it.
60
82434LX/82434NX
3.2.24 SMRSÐSMRAM SPACE REGISTER
Address Offset:
Default Value:
Attribute:
Size:
72h
00h
Read/Write
8 bits
The PCMC supports a 64-KByte SMRAM space that can be selected to reside at the top of main memory,
segment A0000–AFFFFh or segment B0000–BFFFFh. The SMM space defined by this register is not cacheable. This register defines a mechanism that allows the CPU to execute code out of the SMM space at either
A0000h or B0000h while accessing the frame buffer on PCI. The SMRAM Enable bit in the DRAM Control
Register must be 1 to enable the features defined by this register. Register bits [5:3] apply only when segment
A0000-AFFFFh or B0000-BFFFFh are selected.
Bits
Description
7:6
RESERVED
5
OPEN SMRAM SPACE (OSS): When OSS e 1, the CPU can access SMM space without being in
SMM mode. That is, accesses to SMM space are permitted even with SMIACTÝ negated. This bit is
intended to be used during POST to allow the CPU to initialize SMRAM space before the first SMIÝ
interrupt is issued.
4
CLOSE SMRAM SPACE (CSS): When CSS e 1 and SMRAM is enabled, CPU code accesses to the
SMM memory range are directed to SMM space in main memory and data accesses are forwarded to
PCI. This bit allows the CPU to read and write the frame buffer on PCI while executing SMM code.
When CSS e 0 and SMRAM is enabled, all accesses to the SMRAM memory range, both code and
data, are directed to SMRAM (main memory).
3
LOCK SMRAM SPACE (LSS): When LSS e 1, this bit prevents the SMM space from being manually
opened, effectively disabling bit 5 of this register. Only a power-on reset can set this bit to 0.
2:0
SMM BASE SEGMENT (SBS): This field defines the 64 KByte base segment where SMM space is
located. The memory that is defined by this field is non-cacheable.
Bits [2:0] SMRAM Location
Bits [2:0] SMRAM Location
000
Top of main memory
100
Reserved
001
Reserved
101
Reserved
010
A0000–AFFFFh
110
Reserved
011
B0000–BFFFFh
111
Reserved
3.2.25 MSGÐMEMORY SPACE GAP REGISTER
Address Offset:
Default Value:
Attribute:
Size:
78-79h
00h
Read/Write
16 bits
The Memory Space Gap Register defines the starting address and size of a gap in main memory. This register
accommodates ISA devices that have their memory mapped into the 1 MByte – 15.5 MByte range (e.g., an ISA
LAN card or an ISA frame buffer). The Memory Space Gap Register defines a hole in main memory that
transfers the cycles in this address space to the PCI Bus instead of main memory. This area is not cacheable.
The memory space gap starting address must be a multiple of the memory space gap size. For example, a
2 MByte gap must start at 2, 4, 6, 8, 10, 12, or 14 MBytes.
61
82434LX/82434NX
NOTE:
Memory that is disabled by the gap created by this register is remapped to the top of memory. This
remapped memory is accessible, except in the case where this would cause the top of main memory
to exceed 192 MBytes (or 512 MBytes for the 82434NX).
Bits
Description
15
MEMORY SPACE GAP ENABLE (MSGE): MSGE enables and disables the memory space gap.
When MSGE is set to 1, the CPU accesses to the address range defined by this register are
forwarded to PCI bus. The size of the gap created in main memory causes a corresponding amount
of DRAM to be remapped at the top of main memory (top specified by DRB Registers). If the Frame
Buffer Range is programmed below 16 MBytes and within main memory space, the MSG register
must include the Frame Buffer Range. When MSGE is reset to 0, the memory space gap is disabled.
14:12
MEMORY SPACE GAP SIZE (MSGS): This 3 bit field defines the size of the memory space gap. If
the Frame Buffer Range is programmed below 16 MBytes and within main memory space, this
register must include the frame buffer range. The amount of main memory specified by these bits is
remapped to the top of main memory.
Bit [14:12] Memory Gap Size
000
1 MByte
001
2 MBytes
011
4 MBytes
111
8 MBytes
NOTE:
All other combinations are reserved.
11:8
RESERVED
7:4
MEMORY SPACE GAP STARTING ADDRESS (MSGSA): These 4 bits define the starting address
of the memory space gap in the space from 1 MByte – 16 MBytes. These bits are compared against
A [23:20] . The memory space gap starting address must be a multiple of the memory space gap
size. For example, a 2 MBytes gap must start at 2, 4, 6, 8, 10, 12, or 14 MBytes.
3:0
RESERVED
3.2.26 FBRÐFRAME BUFFER RANGE REGISTER
Address Offset:
Default Value:
Attribute:
Size:
7C-7Fh
0000h
Read/Write
32 bits
This 32-bit register enables and disables a frame buffer area and provides attribute settings for the frame
buffer area. The attributes defined in this register are intended to increase the performance of the frame buffer.
The FBR Register can be used to accommodate PCI devices that have their memory mapped onto PCI from
the top of main memory to 4 GByte–512-KByte range (e.g., a linear frame buffer). If the Frame Buffer Range is
located within the 1 MByte–16 MBytes main memory region where DRAM is populated, the Memory Space
Gap Register must be programmed to include the Frame Buffer Range.
62
82434LX/82434NX
Bits
Description
31:20
BUFFER OFFSET (BO): BO defines the starting address of the frame buffer address space in
increments of 1 MByte. This 12-bit field is compared directly against A [31:20] . The frame buffer
range can either be located at the top of memory, including remapped memory or within the memory
space gap (i.e., frame buffer range programmed below 16 MBytes and within main memory space.
When bits [31:20] e 0000h and bit 12 e 0, all features defined by this register are disabled.
19:14
RESERVED
13
BYTE MERGING (BM): Byte merging permits CPU-to-PCI byte writes to the LBX posted write buffer
to be combined into a single transfer on the PCI Bus, when appropriate. When BM is set to 1, byte
merging on CPU-to-PCI posted write cycles is enabled. When BM is reset to 0, byte merging is
disabled.
12
128K VGA RANGE ATTRIBUTE ENABLE (VRAE): When VRAE e 1, the attributes defined in this
register (bits [13, 10:7] ) also apply to the VGA memory range of A0000h – BFFFFh regardless of the
value programmed in the Buffer Offset field. When VRAE e 0, the attributes do not apply to the VGA
memory range. Note that this bit only affects the mentioned attributes of the VGA memory range
and does not enable or disable accesses to the VGA memory range.
11:10
RESERVED
9
NO LOCK REQUESTS (NLR): When NLR is set to 1, the PCMC never requests exclusive access to
a PCI resource via the PCI LOCKÝ signal in the range defined by this register. When NLR is reset to
0, exclusive access via the PCI LOCKÝ signal in the range defined by this register is enabled.
8
RESERVED
7
TRANSPARENT BUFFER WRITES (TBW): When set to a 1, this bit indicates that writes to the
Frame Buffer Range need not be flushed for deadlock or coherence reasons on synchronization
events (i.e., PCI master reads, and the FLSHBUFÝ/MEMREQÝ protocol).
When reset to 0, this bit indicates that upon synchronization events, flushing is required for Frame
Buffer writes posted in the CPU-to-PCI Write Buffer in the LBX
6:4
RESERVED
3:0
BUFFER RANGE (BR): These bits define the size of the frame buffer address space, allowing up to
16 MBytes of frame buffer. If the Frame Buffer Range is within the memory space gap, the buffer
range is limited to 8 MBytes and must be included within the memory space gap. The bits listed
below in the Reserved Buffer Offset (BO) Bits column are ignored by the PCMC for the
corresponding buffer sizes.
Bits [3:0] Buffer Size Reserved Buffer Offset (BO) Bits
0000
1 MByte
None
[20]
0001
2 MBytes
[21:20]
0011
4 MBytes
[22:20]
0111
8 MBytes
[23:20]
1111
16 MBytes
NOTE:
(all other combinations are reserved)
63
82434LX/82434NX
4.0 PCMC ADDRESS MAP
The Pentium processor has two distinct physical address spaces: Memory and I/O. The memory address space is 4 GBytes and the I/O address space
is 64 KBytes. The PCMC maps accesses to these
address spaces as described in this section.
4.1 CPU Memory Address Map
Figure 9 shows the address map for the 4 GByte
Host CPU memory address space. Depending on
the address range and whether a memory gap is
enabled via the MSG Register, the PCMC forwards
CPU memory accesses to either main memory or
PCI memory. Accesses forwarded to main memory
invoke operations on the DRAM interface and accesses forwarded to PCI memory invoke operations
on PCI. Mapping to the PCI Bus permits PCI or
EISA/ISA Bus-based memory.
The main memory size ranges from 2 MBytes –
192 MBytes for the 82434LX and 2 MBytes –
512 MBytes for the 82434NX. Memory accesses
above 192 MBytes (512 MBytes for the 82434NX)
are always forwarded to PCI. In addition, a memory
gap can be created in the 1 MByte–16 MBytes
region that provides a window to PCI-based memory. The location and size of the gap is programmable. Accesses to addresses in the gap are ignored
by the DRAM controller and forwarded to PCI. Note
that CPU memory accesses that are forwarded to
PCI (including the Memory Space Gap) are not
cacheable. Only main memory controlled by the
PCMC DRAM interface is cacheable.
4.2 System Management RAMÐ
SMRAM
The PCMC supports the use of main memory as
System Management RAM (SMRAM) enabling the
use of System Management Mode. This function is
enabled and disabled via the DRAM Control Register. When this function is disabled, the PCMC memory map is defined by the DRB and PAM Registers.
When SMRAM is enabled, the PCMC reserves the
top 64-KBytes of main memory for use as SMRAM.
SMRAM can also be placed at A0000 – AFFFFh or
B0000 – BFFFFh via the SMRAM Space Register.
Enhanced SMRAM features can also be enabled via
this register. PCI masters can not access SMRAM
when it is programmed to the A or B segments.
290479 – 11
Figure 9. CPU Memory Address MapÐFull Range
64
82434LX/82434NX
However, PCI masters can access SMRAM when
the top of memory is selected.
When the 82434NX PCMC detects a CPU stop grant
special cycle (M/IOÝ e 0, D/CÝ e 0, W/RÝ e 1,
A4 e 1, BE [7:0] Ý e FBh), it generates a PCI Stop
Grant Special cycle, with 0002h in the message field
(AD [15:0] ) and 0012h in the message dependent
data field (AD [31:16] ) during the first data phase
(IRDYÝ asserted).
4.3 PC Compatibility Range
The PC Compatibility Range is the first MByte of the
Memory Map. The 512 KByte–1 MByte range is subdivided into several regions as shown in Figure 10.
Each region is provided with programmable attri-
butes in the PAM Registers. The attributes are Read
Enable (RE), Write Enable (WE) and Cache Enable
(CE). The attributes determine readability, writeability and cacheability of the corresponding memory region. When the associated bit in the PAM Register is
set to a 1, the attribute is enabled and when set to a
0 the attribute is disabled. The following rules apply
for cacheability in the first level and second level
caches:
1. If RE e 1, WE e 1, and CE e 1, the region is
cacheable in the first level and second level
caches.
2. If RE e 1, WE e 0, and CE e 1, the region is
cacheable only on code reads (i.e., D/CÝ e 0).
Data reads do not result in a line fill. Writes to the
region are not serviced by the secondary cache,
but are forwarded to PCI.
290479 – 12
Figure 10. CPU Memory Address MapÐPC Compatibility Range
65
82434LX/82434NX
The RE and WE bits for each region are used to
shadow BIOS ROM in main memory for improved
system performance. To shadow a BIOS area, RE is
reset to 0 and WE is set to 1. RE is set to 1 and WE
is reset to 0. Any writes to the BIOS area are forwarded to PCI.
4.4 I/O Address Map
I/O devices (other than the PCMC) are not supported on the Host Bus. The PCMC generates PCI Bus
cycles for all CPU I/O accesses, except to the
PCMC internal registers. Figure 11 shows the mapping for the CPU I/O address space. For the
82434LX, three PCMC registers are located in the
CPU I/O address spaceÐthe Configuration Space
Enable (CSE) Register, the Turbo-Reset Control
(TRC) Register, and the Forward (FORW) Register.
290479 – 13
NOTES:
1. This 82434NX register is only visible when configuration access mechanism Ý1 is enabled (via bit 31 of the CONFADD Register). Otherwise, this I/O range is in PCI I/O space.
2. This 82434NX register is accessed during Dword read/writes to 0CF8h. Byte or word cycles access the corresponding 8-bit registers, even if configuration access mechanism Ý1 is enabled.
Figure 11. CPU I/O Address Map
66
82434LX/82434NX
For the 82434NX, six PCMC registers are located in
the CPU I/O address spaceÐthe Configuration
Space Enable (CSE) Register, the Configuration Address Register (CONFADD), the Turbo-Reset Control (TRC) Register, the Forward (FORW) Register,
the PCI Mechanism Control (PMC) Register, and the
Configuration Data (CONFDATA) Register.
Except for the I/O locations of the above mentioned
registers, all other CPU I/O accesses are mapped to
either PCI I/O space or PCI configuration space. If
the access is to PCI I/O space, the PCI address is
the same as the CPU address. If the access is to PCI
configuration space, the CPU address is mapped to
a configuration space address as described in Section 3.0, Register Description.
NOTE:
# Second level cache sizes and organization
are the same for the 82434LX and
82434NX.
# The general operation of the second level
cache write-back policy is the same for the
82434LX and 82434NX. For example, the
Valid and Modified bits operate the same
for both devices. In addition, snoop operations are the same for both devices, as
well as the handling of flush, flush acknowledge, and write-back special cycles.
5.1 82434LX Cache
If configuration space is enabled via the CSE Register (access mechanism Ý2), the PCMC maps accesses in the address range of C100h to CFFFh to
PCI configuration space. Accesses to the PCMC
configuration register range (C000h to C0FFh) are
intercepted by the PCMC and not forwarded to PCI.
If the configuration space is disabled in the CSE
Register, CPU accesses to the configuration address range (C000h to CFFFh) are forwarded to PCI
I/O space.
The 82434LX PCMC integrates a high performance
write-back/write-through second level cache controller providing integrated tags and a full first level
and second level cache coherency mechanism. The
second level cache controller can be configured to
support either a 256-KByte cache or a 512 KByte
cache using either synchronous burst SRAMs or
standard asynchronous SRAMs. The cache is direct
mapped and can be configured to support either a
write-back or write-through write policy. Parity on the
second level cache data SRAMs is optional.
5.0 SECOND LEVEL CACHE
INTERFACE
The 82434LX contains 4096 address tags. Each tag
represents a sector in the second level cache. If the
second level cache is 256-KByte, each tag represents two cache lines. If the second level cache is
512-KByte, each tag represents four cache lines.
Thus, in the 256-KByte configuration each sector
contains two lines. In the 512-KByte configuration,
each sector contains four lines. Valid and modified
status bits are kept on a per line basis. Thus, in the
case of a 256-KByte cache each tag has two valid
bits and two modified bits associated with it. In the
case of a 512-KByte cache each tag has four valid
and four modified bits associated with it. Upon a
CPU read cache miss, the PCMC inspects the valid
and modified bits within the addressed sector and
writes back to main memory only the lines marked
both valid and modified. All of the lines in the sector
are then invalidated. The line fill will then occur and
the valid bit associated with the allocated line will be
set. Only the requested line will be fetched from
main memory and written into the cache. If no writeback is required, all of the lines in the sector are
marked invalid. The line fill then occurs and the valid
bit associated with the allocated line will be set.
Lines are not allocated on write misses. When a
CPU write hits a line in the second level cache, the
modified bit for the line is set.
This section describes the second level cache interface for the 82434LX Cache (Section 5.1) and the
82434NX Cache (Section 5.2). The differences are
in the following areas:
1. The 82434LX supports both write-through and
write-back cache policies. The 82434NX only
supports the write-back policy.
2. The 82434LX timings are for 60 and 66 MHz and
the 82434NX timings are for 50, 60, and 66 MHz.
Note that the cycle latencies for 60 and 66 MHz
are the same for both devices.
3. When burst SRAMs are used to implement the
secondary cache, address latches are not needed for the 82434NX type SRAM connectivity.
However, a control bit has been added to the
82434NX that permits address latches for
82434LX type SRAM connectivity.
4. A low-power second level cache standby mode
has been added to the 82434NX.
5. There are new or changed cache control bits as
indicated by the shading in Section 3.0, Register
Description. For example, the 82434NX supports
zero wait-state cache at 50 MHz via the zero
wait-state control bit.
67
82434LX/82434NX
The second level cache is optional to allow the
82434LX PCMC to be used in a low cost configuration. A 256-KByte cache is implemented with a single bank of eight 32K x 9 SRAMs if parity is supported or 32K x 8 SRAMs if parity is not supported on
the cache. A 512-KByte cache is implemented with
four 64K x 18 SRAMs if parity is supported or 64K x
16 SRAMs if parity is not supported on the cache.
Two 74AS373 latches complete the cache. Only
main memory controlled by the PCMC DRAM interface is cached. Memory on PCI is not cached.
Figure 12 and Figure 13 depict the organization of
the internal tags in the PCMC configured for a
256 KByte cache and a 512-KByte cache.
290479 – 14
Figure 12. PCMC Internal Tags with 256-KByte Cache
68
82434LX/82434NX
290479 – 15
Figure 13. PCMC Internal Tags with 512-KByte Cache
In the 256-KByte cache configuration A [17:6] form
the tag RAM index. The ten tag bits read from the
tag RAM are compared against A [27:18] from the
host address bus. Two valid bits and two modified
bits are kept per tag in this configuration. Host address bit 5 is used to select between lines 0 and 1
within a sector. In the 512-KByte cache configuration A [18:7] form the tag RAM index. The nine bits
read from the tag RAM are compared against
A [27:19] from the host bus. Four valid bits and four
modified bits are kept per tag. Host address bits 5
and 6 are used to select between lines 0, 1, 2 and 3
within a sector.
The Secondary Cache Controller Register at offset
52h in configuration space controls the secondary
cache size, write and allocation policies, and SRAM
type. The cache can also be enabled and disabled
via this register.
Figure 14 through Figure 18 show the connections
between the PCMC and the external cache data
SRAMs and latches.
69
82434LX/82434NX
290479 – 16
Figure 14. 82434LX Connections to 256-KByte Cache with Standard SRAM
70
82434LX/82434NX
290479 – 17
Figure 15. 82434LX Connections to 512-KByte Cache with Standard SRAM
71
82434LX/82434NX
290479 – 18
Figure 16. 82434LX Connections to 512-KByte Cache with Dual-Byte Select Standard SRAMs
72
82434LX/82434NX
290479 – 19
Figure 17. 82434LX Connections to 256-KByte Cache with Burst SRAM
73
82434LX/82434NX
290479 – 20
Figure 18. 82434LX Connections for 512-KByte Cache with Burst SRAM
74
82434LX/82434NX
When CALE is asserted, HA [18:7] flow through the
address latch. When CALE is negated the address is
captured in the latch allowing the processor to pipeline the next bus cycle onto the address bus. Two
copies of CA [6:3] , COEÝ, CADSÝ and CADVÝ are
provided to reduce capacitive loading. Both copies
should be used when the second level cache is implemented with eight 32K x 8 or 32K x 9 SRAMs.
Either both copies or only one copy can be used
with 64K x 18 or 64K x 16 SRAMs as determined by
the system board layout and timing analysis. The
two copies are always driven to the same logic level.
CAA[4:3] and CAB[4:3] are used to count through
the Pentium processor burst order when standard
SRAMs are used to implement the cache.
With burst SRAMs, the address counting is provided
inside the SRAMs. In this case, CAA [4:3] and
CAB [4:3] are only used at the beginning of a cycle
to load the initial low order address bits into the
burst SRAMs. During CPU accesses, host address
lines 6 and 5 are propagated to the CAA [6:5] and
CAB [6:5] lines and are internally latched. When a
CPU read cycle forces a line replacement in the second level cache, all modified lines within the addressed sector are written back to main memory.
The PCMC uses CAA [6:5] and CAB [6:5] to select
among the lines within the sector. The Cache Output
Enables (COE [1:0] Ý) are asserted to enable the
SRAMs to drive data onto the host data bus. The
Cache Write Enables (CWE [7:0] Ý) allow byte control during CPU writes to the second level cache.
An asynchronous SRAM 512-KByte cache can be
implemented with two different types of SRAM byte
control. Figure 15 depicts the PCMC connections to
a 512 KByte cache using 64K x 18 SRAMs or 64K x
16 SRAMs with two write enables per SRAM. Each
SRAM has a high and low write enable. Figure 16
depicts the PCMC connections to a 512-KByte
cache using 64K x 18 SRAMs or 64K x 16 SRAMs
with two byte select lines per SRAM. Each SRAM
has a high and low byte select.
The type of cache byte control (write enable or byte
select) is programmed in the Cache Byte Control bit
in the Secondary Cache Control Register at configuration space offset 52h. When this bit is set to 0,
byte select control is used. In this mode, the
CBS [7:0] Ý lines are multiplexed onto pins 90, 91,
and 95-100 and CR/W [1:0] Ý pins are multiplexed
onto pins 93 and 94. When this bit is set to 1, byte
write enable control is used. In this mode, the
CWE [7:0] Ý lines are multiplexed onto pins 90, 91,
and 95-100. CADS [1:0] Ý and CADV [1:0] Ý are only
used with burst SRAMs. The Cache Address
Strobes (CADS [1:0] Ý) are asserted to cause the
burst SRAMs to latch the cache address at the beginning of a second level cache access.
CADS [1:0] Ý can be connected to either ADSPÝ or
ADSCÝ on the SRAMs. The Cache Advance signals
(CADV [1:0] Ý) are asserted to cause the burst
SRAMs to advance to the next address of the burst
sequence.
5.1.1 CLOCK LATENCIES (82434LX)
Table 5 and Table 6 list the latencies for various
CPU transfers to or from the second level cache for
standard SRAMs and burst SRAMs. Standard
SRAM access times of 12 ns and 15 ns are recommended for 66 MHz and 60 MHz operation, respectively. Burst SRAM clock access times of 8 ns and
9 ns are recommended for 66 MHz and 60 MHz operation, respectively. Precise SRAM timing requirements should be determined by system board electrical simulation with SRAM I/O buffer models.
Table 5. Second Level Cache Latencies with Standard SRAM (82434LX)
Cycle Type
HCLK Count
Burst Read
3-2-2-2
Burst Write
4-2-2-2
Single Read
3
Single Write
Pipelined Back to Back Burst Reads
Burst Read followed by Pipelined Write
4
3-2-2-2/3-2-2-2
3-2-2-2/4
75
82434LX/82434NX
Table 6. Second Level Cache Latencies with Burst SRAM (82434LX)
Cycle Type
3-1-1-1
Burst Write
3-1-1-1
Single Read
3
Single Write
Pipelined Back to Back Burst Reads
Read Followed by Pipelined Write
5.1.2 STANDARD SRAM CACHE CYCLES
(82434LX)
The following sections describe the activity of the
second level cache interface when standard asynchronous SRAMs are used to implement the cache.
5.1.2.1 Burst Read (82434LX)
Figure 19 depicts a burst read from the second level
cache with standard SRAMs. The CPU initiates the
read cycle by driving address and status onto the
bus and asserting ADSÝ. Initially, the CA [6:3] are a
propagation delay from the host address lines
A [6:3] . Upon sampling W/RÝ active and M/IOÝ inactive, while ADSÝ is asserted, the PCMC asserts
COEÝ to begin a read cycle from the SRAMs. CALE
is negated, latching the address lines on the SRAM
address inputs, allowing the CPU to pipeline a new
address onto the bus. CA [4:3] cycle through the
Pentium processor burst order, completing the cycle. PENÝ is asserted with the first BRDYÝ and
76
HCLK Count
Burst Read
3
3-1-1-1/1-1-1-1
3-1-1-1/2
negated with the last BRDYÝ if parity is implemented on the second level cache data SRAMs and the
MCHK DRAM/Second Level Cache Data Parity bit
in the Error Command Register (offset 70h) is set.
Figure 20 depicts a burst read from the second level
cache with standard 16- or 18-bit wide dual-byte select SRAMs. A single read cycle from the second
level cache is very similar to the first transfer of a
burst read cycle. CALE is not negated throughout
the cycle. COEÝ is asserted as shown above, but is
negated with BRDYÝ.
When the Secondary Cache Allocation (SCA) bit in
the Secondary Cache Control Register is set to 1,
the PCMC performs a line fill in the secondary
cache, even if the CACHEÝ signal from the CPU is
inactive. In this case, AHOLD is asserted to prevent
the CPU from beginning a new cycle while the second level cache line fill is completing.
Back-to-back pipelined burst reads from the second
level cache are shown in the Figure 21.
82434LX/82434NX
290479 – 21
Figure 19. CPU Burst Read from Second Level Cache with Standard SRAM (82434LX)
290479 – 22
Figure 20. Burst Read from Second Level Cache with Dual-Byte Select SRAMs (82434LX)
77
82434LX/82434NX
290479 – 23
Figure 21. Pipelined Back-to-Back Burst Reads from
Second Level Cache with Standard SRAM (82434LX)
Due to assertion of NAÝ, the CPU drives a new address onto the bus before the first cycle is complete.
In this case, the second cycle is a hit in the second
level cache. Immediately upon completion of the first
read cycle, the PCMC begins the second cycle.
When the first cycle completes, the PCMC drives the
new address to the SRAMs on CA [6:3] and asserts
CALE. The second cycle is very similar to the first,
completing at a rate of 3-2-2-2. The cache address
lines must be held at the SRAM address inputs until
the first cycle completes. Only after the last BRDYÝ
is returned, can CALE be asserted and CA [6:3] be
changed. Thus, the pipelined cycle completes at the
same rate as a non-pipelined cycle.
5.1.2.2 Burst Write (82434LX)
A burst write cycle is used to write back a cache line
from the first level cache to either the second level
cache or DRAM. Figure 22 depicts a burst write cycle to the second level cache with standard SRAMs.
78
The CPU initiates the write cycle by driving address
and status onto the bus and asserting ADSÝ. Initially, the CA [6:3] propagate from the host address
lines A [6:3] . CALE is negated, latching the address
lines on the SRAM address inputs, allowing the CPU
to pipeline a new address onto the bus. Burst write
cycles from the Pentium processor always begin
with the low order Qword and advances to the high
order Qword. CWE [7:0] Ý are generated from an internally delayed version of HCLK, providing address
setup time to CWE [7:0] Ý falling and data setup time
to CWE [7:0] Ý rising edges. HIG [4:0] are driven to
PCMWQ (Post CPU to Memory Write Buffer Qword)
only when the PCMC is programmed for a writethrough write policy. When programmed for writeback mode, the modified bit associated with the line
is set within the PCMC. The single write cycle is very
similar to the first write of a burst write cycle. A burst
read cycle followed by a pipelined write cycle with
standard SRAMs is depicted in Figure 24.
82434LX/82434NX
290479 – 24
Figure 22. Burst Write to Second Level Cache with Standard SRAM (82434LX)
290479 – 25
Figure 23. Burst Write to Second Level Cache with Dual-Byte Select Standard SRAMs (82434LX)
79
82434LX/82434NX
290479 – 26
Figure 24. Burst Read Followed by Pipelined Write with Standard SRAM (82434LX)
5.1.2.3 Cache Line Fill (82434LX)
If the CPU issues a memory read cycle to cacheable
memory that is not in the second level cache, a first
and second level cache line fill occurs. Figure 25
depicts a CPU read cycle that results in a line fill into
the first and second level caches.
80
Figure 27 depicts the host bus activity during a CPU
read cycle that forces a write-back from the second
level cache to the CPU-to-memory posted write buffer as the DRAM read cycle begins.
82434LX/82434NX
290479 – 27
Figure 25. Cache Line Fill with Standard SRAM, DRAM Page Hit (82434LX)
81
82434LX/82434NX
290479 – 28
Figure 26. Cache Line Fill with Dual-Byte Select Standard SRAM, DRAM Page Hit (82434LX)
82
82434LX/82434NX
290479 – 29
Figure 27. CPU Cache Read Miss, Write-Back, Line Fill with Standard SRAM (82434LX)
The CPU issues a memory read cycle that misses in
the second level cache. In this instance, a modified
line in the second level cache must be written back
to main memory before the new line can be filled
into the cache. The PCMC inspects the valid and
modified bits for each of the lines within the addressed sector and writes back only the valid lines
within the sector that are in the modified state. During the write-back cycle, CA [4:3] begin with the initial value driven by the Pentium processor and proceed in the Pentium processor burst order. CA [6:5]
are used to count through the lines within the addressed sector. When two or more lines must be
written back to main memory, CA [6:5] count in the
direction from line 0 to line 3. CA [6:5] advance to
the next line to be written back to main memory,
skipping lines that are not modified. Figure 23 depicts the case of just one of the lines in a sector
being written back to main memory. In this case, the
entire line can be posted in the CPU-to-Main memory posted write buffer by driving the HIG [4:0] lines to
the PCMWQ command as each Qword is read from
the cache. At the same time, the required DRAM
read cycle is beginning. As soon as the de-allocated
line is written into the posted write buffer, the
HIG [4:0] lines are driven to CMR (CPU Memory
Read) to allow data to propagate from the DRAM
data lines to the CPU data lines. The CWE [7:0] Ý
lines are not generated from a delayed version of
HCLK (as they are in the case of CPU to second
level cache burst write), but from ordinary HCLK rising edges. CMR is driven on the HIG [4:0] lines
83
82434LX/82434NX
throughout the DRAM read portion of the cycle. With
the fourth assertion of BRDYÝ the HIG [4:0] lines
change to NOPC. The LBXs however, do not tristate the host data lines until MDLE rises.
CWE [7:0] Ý and MDLE track such that MDLE will
not rise before CWE [7:0] Ý. Thus, the LBXs continue to drive the host data lines until CWE [7:0] Ý are
negated. CA [6:3] remain at the valid values until the
clock after the last BRDYÝ, providing address hold
time to CWE [7:0] Ý rising.
PENÝ is asserted as shown if the MCHK DRAM/L2
Cache Data Parity Error bit in the Error Command
Register (offset 70h) is set. If the second level cache
supports parity, PENÝ is always asserted during
CPU read cycles in the third clock in case the cycle
hits in the cache.
If more than one line must be written back to main
memory, the PCMC fills the CPU-to-Main Memory
Posted Write Buffer and loads another Qword into
the buffer as each Qword write completes into main
memory. The writes into DRAM proceed as page hit
write cycles from one line to the next, completing at
a rate of X-4-4-4-5-4-4-4-5-4-4-4 for a three line
write-back. All modified lines except for the last one
to be written back are posted and written to memory
before the DRAM read cycle begins. The last line to
be written back is posted as the DRAM read cycle
begins. Thus, the read data is returned to the CPU
before the last line is retired to memory.
The line which was written into the second level
cache is marked valid and unmodified by the PCMC.
All the other lines in the sector are marked invalid. A
subsequent CPU read cycle which hits in the same
sector (but a different line) in the second level cache
would then simply result in a line fill without any
write-back.
5.1.3 BURST SRAM CACHE CYCLES (82434LX)
The following sections show the activity of the second level cache interface when burst SRAMs are
used for the second level cache.
5.1.3.1 Burst Read (82434LX)
Figure 28 depicts a burst read from the second level
cache with burst SRAMs.
290479 – 30
Figure 28. CPU Burst Read from Second Level Cache with Burst SRAM (82434LX)
84
82434LX/82434NX
The cycle begins with the CPU driving address and
status onto Host Bus and asserting ADSÝ. The
PCMC asserts CADSÝ and COEÝ in the second
clock. After the address is latched by the burst
SRAMs and the PCMC determines that no writeback cycles are required from the second level
cache, CALE is negated. Back-to-back burst reads
from the second level cache are shown in Figure 29.
When the Secondary Cache Allocation (SCA) bit in
the Secondary Cache Control Register is set to 1,
the PCMC performs a line fill in the secondary
cache, even if the CACHEÝ signal from the CPU is
negated. In this case, AHOLD is asserted to prevent
the CPU from beginning a new cycle while the second level cache line fill is completing.
Back-to-back burst reads which hit in the second
level cache complete at a rate of 3-1-1-1/1-1-1-1
with burst SRAMs. As the last BRDYÝ is being returned to the CPU, the PCMC asserts CADSÝ causing the SRAMs to latch the new address. This allows
the data for the second cycle to be transferred to the
CPU on the clock after the first cycle completes.
290479 – 31
Figure 29. Pipelined Back-to-Back Burst Reads from Second Level Cache (82434LX)
85
82434LX/82434NX
5.1.3.2 Burst Write (82434LX)
A burst write cycle is used to write back a line from
the first level cache to either the second level cache
or DRAM. A burst write cycle from the first level
cache to the second level cache is shown in Figure 30.
The Pentium processor always writes back lines
starting with the low order Qword advancing to the
high order Qword. CADSÝ is asserted in the second
clock. CWE [7:0] Ý and BRDYÝ are asserted in the
third clock. CADVÝ assertion is delayed by one
clock relative to the burst read cycle. HIG [4:0] are
driven to PCMWQ (Post CPU-to-Memory Write Buffer Qword) only when the PCMC is programmed for a
write-through write policy. When programmed for
write-back mode, the modified bit associated with
the line is set within the PCMC. The single write is
very similar to the first write in a burst write. CADSÝ
is asserted in the second clock. BRDYÝ and
CWE [7:0] Ý are asserted in the third clock. A burst
read cycle followed by a pipelined single write cycle
is depicted in Figure 31.
290479 – 32
Figure 30. Burst Write to Second Level Cache with Burst SRAM (82434LX)
86
82434LX/82434NX
290479 – 33
Figure 31. Burst Read Followed by Pipelined Single Write Cycle with Burst SRAM (82434LX)
87
82434LX/82434NX
5.1.3.3 Cache Line Fill (82434LX)
Figure 33 depicts a CPU read cycle which forces a
write-back in the second level cache.
If the CPU issues a memory read cycle to cacheable
memory which does not hit in the second level
cache, a cache line fill occurs. Figure 32 depicts a
first and second level cache line fill with burst
SRAMs.
290479 – 34
Figure 32. Cache Line Fill with Burst SRAM, DRAM Page Hit, 7-4-4-4 Timing (82434LX)
88
82434LX/82434NX
290479 – 35
Figure 33. CPU Cache Read Miss, Write-Back, Line Fill with Burst SRAM (82434LX)
The CPU issues a memory read cycle which misses
in the second level cache. In this instance, a modified line in the second level cache must be written
back to main memory before the new line can be
filled into the cache. The PCMC inspects the valid
and modified bits for each of the lines within the
addressed sector and writes back only the valid
lines within the sector that are marked modified.
CA [6:5] are used to count through the lines within
the addressed sector. When two or more lines must
be written back to main memory, CA [6:5] count in
the direction from line 0 to line 3 after each line is
written back. Figure 29 depicts the case of just one
89
82434LX/82434NX
of the lines in a sector being written back to main
memory. In this case, the entire line can be posted in
the CPU-to-Memory Posted Write Buffer by driving
the HIG[4:0] lines to PCMWQ as each Qword is
read from the cache. At the same time, the required
DRAM read cycle is beginning. After the de-allocated line is written into the posted write buffer, the
HIG [4:0] lines are driven to CMR (CPU Memory
Read) to allow data to propagate from the DRAM
data lines to the CPU data lines. Figure 29 assumes
that the read from DRAM is a page hit and thus the
first Qword is already read from the DRAMs when
the transfer from cache to the CPU to Memory posting buffer is complete. The rest of the DRAM cycle
completes at a -4-4-4 rate. CADVÝ is asserted with
the last three BRDYÝ assertions. CMR is driven on
the HIG [4:0] lines throughout the DRAM read portion of the cycle. Upon the fourth assertion of
BRDYÝ the HIG [4:0] lines change to NOPC.
PENÝ is asserted as shown if the MCHK DRAM/L2
Cache Data Parity Error bit in the Error Command
Register (offset 70h) is set. If the second level cache
supports parity, PENÝ is always asserted during
CPU read cycles in clock 3 in case the cycle hits in
the cache.
If more than one line must be written back to main
memory, the PCMC fills the CPU-to-Main Memory
Posted Write Buffer and loads another Qword into
the buffer as each Qword write completes into main
memory. The writes into DRAM proceed as page hit
write cycles from one line to the next, completing at
a rate of X-4-4-4-5-4-4-4-5-4-4-4 for a three line
write-back when programmed for X-4-4-4 DRAM
write timing or X-3-3-3-4-3-3-3-4-3-3-3 when programmed for X-3-3-3 DRAM write timing. All modified lines except for the last one to be written back
to memory are posted and retired to memory before
the DRAM read cycle begins. The last line to be written back is posted as the DRAM read cycle begins.
Thus, the read data is returned to the CPU before
the last line is retired to memory.
90
The line which was written into the second level
cache is marked valid and unmodified by the PCMC.
All the other lines in the block are marked invalid. A
subsequent CPU read cycle which hits the same
sector (but a different line) in the second level cache
results in a line fill without any write-back.
5.1.4 SNOOP CYCLES
Snoop cycles are the same for the 82434LX and
82434NX. The inquire cycle is used to probe the first
level and second level caches when a PCI master
attempts to access main memory. This is done to
maintain coherency between the first and second
level caches and main memory. When a PCI master
first attempts to access main memory a snoop request is generated inside the PCMC. The PCMC
supports up to two outstanding cycles on the CPU
address bus at a time. Outstanding cycles include
both CPU initiated cycles and snoop cycles. Thus, if
the Pentium processor pipelines a second cycle
onto the host address bus, the PCMC will not issue a
snoop cycle until the first CPU cycle terminates. If
the PCMC were to initiate a snoop cycle before the
first CPU cycle were complete then for a brief period
of time, three cycles would be outstanding. Thus, a
snoop request is serviced with a snoop cycle only
when either no cycle is outstanding on the CPU bus
or one cycle is outstanding.
Snoop cycles are performed by driving the PCI master address onto the CPU address bus and asserting
EADSÝ. The Pentium processor then performs a
tag lookup to determine if the addressed memory is
in the first level cache. At the same time the PCMC
performs an internal tag lookup to determine if the
addressed memory is in the second level cache. Table 7 describes how a PCI master read from main
memory is serviced by the PCMC.
82434LX/82434NX
Table 7. Data Transfers for PCI Master Reads from Main Memory
Snoop Result
First Level
Cache
Action
Second Level
Cache
Miss
Miss
Data is transferred from DRAM to PCI.
Miss
Hit Unmodified Line
Data is transferred directly from second level cache to PCI. The
line remains valid and unmodified in the second level cache.
Miss
Hit Modified Line
Data is transferred directly from second level cache to PCI. Line
remains valid and modified in the second level cache. The line
is not written to DRAM.
Hit Unmodified Line
Miss
Data is transferred from DRAM to PCI.
Hit Unmodified Line
Hit Unmodified Line
Data is transferred directly from second level cache to PCI. The
line remains valid and unmodified in the second level cache.
Hit Unmodified Line
Hit Modified Line
Data is transferred directly from second level cache to PCI. Line
remains valid and modified in the second level cache. The line
is not written to DRAM.
Hit Modified Line
Miss
A write-back from first level cache occurs. The data is sent to
both PCI and the CPU-to-Memory Posted Write Buffer. The
CPU-to-Memory Posted Write Buffer is then written to memory.
Hit Modified Line
Hit Unmodified Line
A write-back from first level cache occurs. The data is posted to
PCI and written into the second level cache. When the second
level cache is in write-back mode, the line is marked modified
and is not written to DRAM. When the second level cache is in
write-through mode, the line is posted and then written to
DRAM.
Hit Modified Line
Hit Modified Line
A write-back from first level cache occurs. The data is posted to
PCI and written into the second level cache. The line is not
written to DRAM. This scenario can only occur when the
second level cache is in write-back mode.
PCI master write cycles never result in a write directly into the second level cache. A snoop hit to a modified line in either the first level or second level cache
results in a write-back of the line to main memory.
The line is invalidated and the PCI write to main
memory occurs after the write-back completes. The
other lines in the sector are not written back to main
memory or invalidated. A PCI master write snoop hit
to an unmodified line in either the first level or second level cache results in the line being invalidated.
Table 8 describes the actions taken by the PCMC
when a PCI master writes to main memory.
91
82434LX/82434NX
Table 8. Data Transfers for PCI Master Writes to Main Memory
Snoop Result
First Level
Cache
Action
Second Level
Cache
Miss
Miss
The PCI master write data is transferred from PCI to DRAM.
Miss
Hit Unmodified Line
The PCI master write data is transferred from PCI to DRAM.
The line is invalidated in the second level cache.
Miss
Hit Modified Line
A write-back from second level cache to DRAM occurs. The
PCI master write data is then written to DRAM. The line is
invalidated in the second level cache.
Hit Unmodified Line
Miss
The first level cache line is invalidated. The PCI master write
data is written to DRAM.
Hit Unmodified Line
Hit Unmodified Line
The line is invalidated in both the first level and second level
caches. The PCI master write data is written to DRAM.
Hit Unmodified Line
Hit Modified Line
The first level cache line is invalidated. The second level cache
line is written back to main memory and invalidated. The PCI
master write data is then written to DRAM.
Hit Modified Line
Miss
The first level cache line is written back to DRAM and
invalidated. The PCI master write data is then written to DRAM.
Hit Modified Line
Hit Unmodified Line
The first level cache line is written back to DRAM and
invalidated. The second level cache line is invalidated. The PCI
master write data is then written to DRAM.
Hit Modified Line
Hit Modified Line
The first level cache line is written back to DRAM and
invalidated. The second level cache line is invalidated. The PCI
master write data is then written to DRAM.
A snoop hit results in one of three transfers; a writeback from the first level cache posted to the LBXs, a
write-back from the second level cache posted to
the LBXs or a write-back from the first level cache
92
posted to the LBXs and written to the second level
cache. A snoop cycle that does not result in a writeback is depicted in Figure 34.
82434LX/82434NX
290479 – 36
Figure 34. Snoop Hit to Unmodified Line in First Level Cache or Snoop Miss
The PCMC begins to service the snoop request by
asserting AHOLD, causing the Pentium processor to
tri-state the address bus in the clock after assertion.
In the case of a PCI master read cycle, the PCMC
drives the DPRA (Drive PCI Read Address) command onto the HIG [4:0] lines causing the LBXs to
drive the PCI address onto the host address bus.
For a write cycle, the PCMC drives the DPWA (Drive
PCI Write Address to CPU Address Bus) command
on the HIG [4:0] lines, also causing the LBXs to begin driving the host address bus. The PCMC then
asserts EADSÝ, initiating the snoop cycle to the
CPU. The INV signal is asserted by the PCMC only
during snoops due to PCI master writes. INV remains negated during snoops due to PCI master
reads. If the snoop results in a hit to a modified line
in the first level cache, the Pentium processor asserts HITMÝ. The PCMC samples the HITMÝ signal
two clocks after the CPU samples EADSÝ asserted
to determine if the snoop hit in the first level cache.
By this time the PCMC has completed an internal tag
lookup to determine if the line is in the second level
cache. Since this snoop does not result in a writeback, the NOPC command is driven on the HIG [4:0]
lines, causing the LBXs to tri-state the address bus.
The sequence ends with AHOLD negation.
If the Pentium processor asserts ADSÝ in the same
clock as the PCMC asserts AHOLD, the PCMC will
assert BOFFÝ in two cases. First, if the snoop cycle
hits a modified line in the first level cache, the PCMC
will assert BOFFÝ for 1 HCLK to re-order the writeback around the currently sending cycle. Second, if
the snoop requires a write-back from the second level cache, the PCMC will assert BOFFÝ to enable
the write-back from the secondary cache SRAMs.
Figure 35 depicts a snoop hit to a modified line in the
first level cache due to a PCI master memory read
cycle.
The snoop cycle begins when the PCMC asserts
AHOLD causing the CPU to tri-state the address
bus. The PCMC drives the DPRA (Drive PCI Read
Address) command on to the HIG [4:0] lines causing
the LBXs to drive the PCI address onto the host address bus. The PCMC then asserts EADSÝ, initiating the snoop to the first level cache. INV is not
asserted since this is a PCI master read cycle. INV is
only asserted with EADSÝ when the snoop cycle is
in response to a PCI master write cycle. As the CPU
is sampling EADSÝ asserted, the PCMC latches the
address. Two clocks later, the PCMC completes the
93
82434LX/82434NX
290479 – 37
Figure 35. Snoop Hit to Modified Line in First Level Cache, Post Memory and PCI
internal tag lookup to determine if the line is in the
second level cache. In this instance, the snoop hits
a modified line in the first level cache and misses in
the second level cache. Thus, the second level
cache is not involved in the write-back cycle. The
PCMC allows the LBXs to stop driving the address
lines by driving NOPC command on the HIG [4:0]
lines. The CPU then drives the write-back cycle onto
the bus by asserting ADSÝ and driving the writeback data on the data lines even though AHOLD is
still asserted. The write-back into the LBX buffers
occurs at a rate of 3-1-1-1. The PCMC drives
PCMWFQ on the HIG [4:0] lines for one clock causing the write data to be posted to both PCI and main
memory. For the next three clocks, the HIG [4:0]
lines are driven to PCMWNQ, posting the final three
Qwords to both PCI and main memory.
A similar transfer from first level cache to the LBXs
occurs when a snoop due to a PCI master write hits
a modified line in the first level cache. In this case,
the write-back is transferred to the CPU-to-Memory
Posted Write Buffer. If the line is in the second level
cache, it is invalidated. The cycle is similar to the
snoop cycle shown above with two exceptions. The
PCMC drives the DPWA command on the HIG [4:0]
lines instead of the DPRA command. During the four
clocks where the PCMC drives BRDYÝ active to the
94
CPU, it also drives PCMWQ on the HIG [4:0] lines,
causing the write to be posted to main memory.
In both of the above cases where a write-back from
the first level cache is required, AHOLD is asserted
until the write-back is complete. If the CPU has begun a read cycle directed to PCI and the snoop results in a hit to a modified line in the first level cache,
BOFFÝ is asserted for one clock to abort the CPU
read cycle and re-order the write-back cycle before
the read cycle.
When a PCI master read or write cycle hits a modified line in the second level cache and either misses
in the first level cache or hits an unmodified line in
the first level cache, a write-back from the second
level cache to the LBXs occurs. When a PCI master
write snoop hits an unmodified line in the second
level cache and either misses in the first level cache
or hits an unmodified line in the first level cache, no
data transfer from the second level cache occurs.
The line is simply invalidated. In the case of a PCI
master write cycle, the line is invalidated in both the
first level and second level caches. In the case of a
PCI master memory read cycle, neither cache is invalidated. A PCI master read from main memory
which hits either a modified or unmodified line in the
second level cache is shown in Figure 36.
82434LX/82434NX
290479 – 38
Figure 36. Snoop Hit to Modified Line in Second Level Cache, Store in PCI Read Prefetch Buffer
The snoop cycle begins with the PCMC asserting
AHOLD, causing the CPU to tri-state the host address bus. The PCMC drives the DPRA command
enabling the LBXs to drive the snoop address onto
the host address bus. The PCMC asserts EADSÝ.
INV is not asserted in this case since the snoop cycle is in response to a PCI master read cycle. If the
snoop were in response to a PCI master write cycle
then INV would be asserted with EADSÝ. Two
clocks after the CPU samples EADSÝ active, the
PCMC completes the internal tag lookup. In this
case the snoop hit either an unmodified line or a
modified line in the second level cache. Since
HITMÝ is inactive, the snoop did not hit in the first
level cache. The PCMC then schedules a read from
the second level cache to be written to the LBXs.
When the CPU burst cycle completes the PCMC negates the control signals to the second level cache
and asserts CALE opening the cache address latch
and allowing the snoop address to flow through to
the SRAMs. The second level cache executes a
read sequence which completes at 3-2-2-2 in the
case of standard SRAMs and 3-1-1-1 in the case of
burst SRAMs. During all snoop cycles where a writeback from the second level cache is required,
BOFFÝ is asserted throughout the write-back cycle.
This prevents the deadlock that would occur if the
CPU is in the middle of a non-postable write and the
data bus is required for the second level cache
write-back.
When using burst SRAMs, the read from the SRAMs
follows the Pentium processor burst order. However,
the memory to PCI read prefetch buffer in the LBXs
is organized as a FIFO and cannot accept data out
of order. The SWB0, SWB1, SWB2 and SWB3 commands are used to write data into the buffer in ascending order. In the above example, the PCI master
requests a data item which hits Qword 0 in the
cache, thus CA [4:3] count through the following sequence: 0, 1, 2, 3 (00, 01, 10, 11). If the PCI mas-
95
82434LX/82434NX
ter requests a data item that hits Qword 1, the SWB0
command is sent via the HIG [4:0] lines to store
Qword 1in the first buffer location. The next read
from the cache is not in ascending order, thus a
NOPC is sent on the HIG [4:0] lines. This Qword is
not posted in the buffer. The next read from the
cache is to Qword 3. SWB2 is sent on the HIG [4:0]
lines. The final read from the cache is Qword 2.
SWB1 is sent on the HIG [4:0] lines. Thus, Qword 1
is placed in entry 0 in the buffer, Qword 2 is placed
in entry 1 in the buffer and Qword 3 is placed in entry
2 in the buffer. The ordering between the Qwords
read from the cache and the HIG[4:0] commands
when using burst SRAMs is summarized in Table 9.
Table 9. HIG [4:0] Command Sequence for
Second Level Cache to PCI Master Read
Prefetch Buffer Transfer
96
Burst Order
from Cache
HIG [4:0] Command
Sequence
0, 1, 2, 3
SWB0, SWB1,
SWB2, SWB3
1, 0, 3, 2
SWB0, NOPC,
SWB2, SWB1
2, 3, 0, 1
SWB0, SWB1,
NOPC, NOPC
3, 2, 1, 0
SWB0, NOPC,
NOPC, NOPC
When using standard asynchronous SRAMs, the
read from the SRAMs occurs in a linear burst order.
Thus, CAA [4:3] and CAB [4:3] count in a linear burst
order and the Store Write Buffer commands are sent
in linear order. The burst ends at the cache line
boundary and does not wrap around and continue
with the beginning of the cache line.
A PCI master write cycle which hits a modified line in
the second level cache and either hits an unmodified
line in the first level cache or misses in the first level
cache will also cause a transfer from the second
level cache to the LBXs. In this case, the read from
the SRAMs is posted to main memory and the line is
invalidated in the second level cache. The cycle
would differ only slightly from the above cycle. INV
would be asserted with EADSÝ. Instead of the
DPRA command, the PCMC would use the DPWA
command to drive the snoop address onto the host
address bus. The write would be posted to the
DRAM, thus the PCMC would drive the PCMWQ
command on the HIG [4:0] lines to post the write to
DRAM.
A snoop cycle can result in a write-back from the
first level cache to both the second level and LBXs
in the case of a PCI master read cycle which hits a
modified line in the first level cache and hits either a
modified or unmodified line in the second level
cache. The line is written to both the second level
cache and the memory to PCI read prefetch buffer.
The cycle is shown in Figure 37.
82434LX/82434NX
290479 – 39
Figure 37. Snoop Hit to Modified Line in First Level Cache, Write-Back from First Level Cache to
Second Level Cache and Send to PCI
This cycle is shown for the case of a second level
cache with burst SRAMs. In this case, as it completes the second level cache tag lookup, the PCMC
samples HITMÝ active. The write-back is written to
the second level cache and simultaneously stored in
the memory to PCI prefetch buffer. In the case
shown in Figure 33, the PCI master requests a data
item which is contained in Qword 0 of the cache line.
Note that a write-back from the first level cache always starts with Qword 0 and finishes with Qword 3.
Thus the HIG [4:0] lines are sequenced through the
following order: SWB0, SWB1, SWB2, SWB3. If the
PCI master requests a data item which is contained
in Qword 1, the HIG [4:0] lines sequence through the
following order: NOPC, SWB0, SWB1, SWB2. If the
PCI master requests a data item which is contained
in Qword 2, the HIG [4:0] lines sequence through the
following order: NOPC, NOPC, SWB0, SWB1. If the
PCI master requests a data item which is contained
in Qword 3, the HIG [4:0] lines sequence through the
following order: NOPC, NOPC, NOPC, SWB0.
AHOLD is negated after the write-back cycle is complete.
If the CPU has begun a read cycle directed to PCI
and the snoop results in a hit to a modified line in the
first level cache, BOFFÝ is asserted for one clock to
abort the CPU read cycle and re-order the writeback cycle before the pending read cycle.
97
82434LX/82434NX
5.1.5 FLUSH, FLUSH ACKNOWLEDGE AND
WRITE-BACK SPECIAL CYCLES
There are three special cycles that affect the second
level cache, flush, flush acknowledge, and writeback. If the processor executes an INVD instruction,
it will invalidate all unmodified first level cache lines
and issue a flush special cycle. If the processor executes a WBINVD instruction, it will write back all
modified first level cache lines, invalidate the first
level cache, and issue a write-back special cycle followed by a flush special cycle. If the Pentium processor FLUSHÝ pin is asserted, the CPU will writeback all modified first level cache lines, invalidate
the first level cache, and issue a flush acknowledge
special cycle.
The second level cache behaves the same way in
response to the flush special cycle and flush acknowledge special cycle. Each tag is read and the
valid and modified bits are examined. If the line is
both valid and modified it is written back to main
memory and the valid bit for that line is reset. All
valid and unmodified lines are simply marked invalid.
The PCMC advances to the next tag when all lines
within the current sector have been examined.
BRDYÝ is returned to the Pentium processor after
all modified lines in the second level cache have
been written back to main memory and all of the
valid bits for the second level cache are reset. The
sequence of write-back cycles will only be interrupted to service a PCI master cycle.
The write-back special cycle is ignored by the PCMC
because all modified lines will be written back to
main memory by the following flush special cycle.
Upon decoding a write-back special cycle, the
PCMC simply returns BRDYÝ to the Pentium processor.
5.2 82434NX Cache
The 82434NX PCMC integrates a high performance
write-back second level cache controller, tag RAM
and a full first and second level cache coherency
mechanism. The cache is either 256 KBytes or
512 KBytes using either synchronous burst SRAMs
or standard asynchronous SRAMs. Parity on the
data SRAMs is optional. The cache uses a writeback write policy. Write-through mode is not supported.
The 82434NX PCMC supports a direct mapped secondary cache. The PCMC contains 4096 tags. Each
98
tag represents a sector in the cache. If the cache is
512 KB, each sector contains four cache lines. If the
cache is 256 KB, each sector contains two cache
lines. Valid and Modified bits are kept on a per line
basis. The 82434NX Tag RAM is 1 bit wider than the
82434LX Tag RAM.
The PCMC can be configured to cache main memory on read cycles even when CACHEÝ is not asserted. When bit 4 in the Secondary Cache Control Register (offset 52h) is set to 1, all accesses to main
memory, except those to SMM memory or any range
marked non-cacheable via the PAM registers, are
cached in the secondary cache. Accesses with
CACHEÝ asserted result in a line fill in both the first
and second level cache while accesses with
CACHEÝ negated result in a line fill only in the second level cache. When bit 4 in the SCC Register is
set to 0, only access with CACHEÝ asserted can
generate a first and second level cache line fill.
When a Halt or Stop Grant Special Cycle is detected
from the CPU, the 82434NX PCMC places the second level cache into the low power stand-by mode
by deselecting the SRAMs and then generates the
corresponding special cycle on PCI. (i.e., if the CPU
cycle was a halt special cycle then the PCMC generates a halt special cycle on PCI and if the CPU cycle
is a stop grant special cycle the PCMC generates a
stop grant special cycle on PCI).
When a burst SRAM secondary cache is implemented, bit 2 of the Secondary Cache Control Register
(offset 52h) is used to select between 82434LX
SRAM connectivity and the new 82434NX SRAM
connectivity. When set to 0, the secondary cache
interface is in 82430-compatible mode. (i.e., the four
low order address lines on the SRAMs are connected to CAA/B [6:3] on the PCMC. When set to 1, second level cache stand-by is enabled and no latch is
used between the host CPU address lines and the
SRAM address lines. All of the SRAM address lines
are then connected directly to the CPU address
lines. Write-back addresses are driven by the PCMC
over the host address lines. When a standard SRAM
secondary cache is implemented, bit 2 of the Secondary Cache Control Register (offset 52h) is used
to enable second level cache stand-by. The default
value of this bit is 0.
Figure 38 and Figure 41 show the connections between the PCMC and the external cache data
SRAMs and latch for the case of an asynchronous
SRAM cache.
82434LX/82434NX
290479 – 40
NOTE:
In this mode, SRAMs which internally gate ADSPÝ with CSÝ must be used.
Figure 38. 512 KByte Secondary Cache, Synchronous Burst SRAM (82434NX)
99
82434LX/82434NX
290479 – 41
Figure 39. 512 KByte Secondary Cache, Standard Dual-Byte-Select (Asynch) SRAM, 50, 60 & 66 MHz
Figure 38 depicts the PCMC connections to a
512 KByte burst SRAM secondary cache when the
PCMC is configured for 50, 60, or 66 MHz operation.
Host address lines HA [18:3] are connected directly
to the SRAM address lines, A [15:0] . ADSÝ from the
CPU is connected to ADSPÝ on the SRAMs.
CADV0Ý implements the address advance (ADVÝ)
functionality. A new signal, CCSÝ, is multiplexed
onto the CADV1Ý pin. When bit 2 in the SCC register is set to 1, SRAMs containing logic which gates
ADSPÝ with CSÝ must be used. When negated,
CCSÝ prevents the SRAMs from latching a new address due to a pipelined ADSÝ from the CPU during
cache line fills. Note that, unlike the burst SRAM
configuration with the 82430 PCIset, no external
latch is used between the CPU address bus and the
SRAM address lines. The SRAM Connectivity bit (bit
2) in the Secondary Cache Control register (offset
52h) must be set to 1 when using this cache configuration.
100
If the tag lookup results in a miss in the cache and
the sector to be replaced contains one or more modified lines, the PCMC drives the write-back address
from the A [18:3] lines on the host bus. Although not
used in the write-back, A [31:19] (or A [31:18] in the
case of a 256 KB cache) are driven to valid logic
levels by the PCMC.
Figure 39 depicts the 82434NX PCMC connections
to a 512 KByte standard asynchronous SRAM secondary cache. Figure 40 depicts the 82434NX connections to a 256 KByte asynchronous SRAM secondary cache. Host address lines HA [18:7] are
driven through an external latch to form the upper
SRAM address lines, CA [18:7] . CA [6:3] are
driven from the PCMC. Figure 41 depicts the
82434NX PCMC connections to a 512 KByte standard SRAM secondary cache with dual-write-enable
SRAMs.
82434LX/82434NX
290479 – 42
Figure 40. 82434NX Connections to 256 KByte Cache with Standard SRAM
101
82434LX/82434NX
290479 – 43
Figure 41. 82434NX Connections to 512 KByte Cache with Standard SRAM
5.2.1 CYCLE LATENCY SUMMARY (82434NX)
Table 10 and Table 11 summarize the clock latencies for CPU memory cycles which hit in the secondary cache.
Table 10. Secondary Cache Latencies with
Synchronous Burst SRAM
50, 60 and
66 MHz
Cycle Type
Burst Read
3-1-1-1
Burst Write
3-1-1-1
Single Read
3
Single Write
3
Pipelined Back-to-Back
Burst Reads
3-1-1-1-1-1-1-1
Burst Read Followed
by Pipelined Write
3-1-1-1-2
102
Table 11. Secondary Cache Latencies with
Standard Asynchronous SRAM (82434NX)
50, 60 and
66 MHz
Cycle Type
Burst Read
3-2-2-2
Burst Write
4-2-2-2
Single Read
3
Single Write
4
Pipelined Back-to-Back
Burst Reads
3-2-2-2-3-2-2-2
Burst Read Followed
by Pipelined Write
3-2-2-2-4
82434LX/82434NX
The 60 MHz and 66 MHz asynchronous SRAM latencies require 15 ns and 12 ns SRAMs, respectively. The 82434NX PCMC supports asynchronous
SRAMs at 50 MHz. The 50 MHz (1 wait-state) timings require 20 ns SRAMs. The burst SRAMs
speeds for 66 MHz, 60 MHz and 50 MHz operation
are 8 ns, 9 ns, and 13 ns clock-to-output valid into a
0 pF test load. The SRAM access times listed in this
paragraph are recommendations. Actual access
time requirements are a function of system board
layout and routing and should be validated with electrical simulation.
5.2.2 STANDARD SRAM CACHE CYCLES
(82434NX)
At 50, 60 and 66 MHz, the timing of the second level
cache interface with standard asynchronous SRAMs
is identical to the timing in the 82430LX PCIset.
Compared to the 82434LX second level cache, one
additional connection can be made from the PCMC
to the SRAMs. The CCS [1:0] Ý pins, in the case of
asynchronous SRAMs, are multiplexed onto the
CADV [1:0] Ý pins. These are then connected to the
SRAM CSÝ pins. The two copies are functionally
identical. The two copies are provided for timing reasons. These pins allow the PCMC to deselect the
SRAMs, putting them into standby mode. When a
halt special cycle or a stop grant special cycle is
detected from the CPU, the PCMC negates
CCS [1:0] Ý, placing the SRAMs into the low power
standby mode. The PCMC then generates a halt or
stop grant special cycle on PCI.
stand-by and into active mode, enabling the SRAMs
to service the cycle in the case of a hit to the cache.
The PCMC asserts CCS [1:0] Ý as a propagation delay from the falling edge of ADSÝ. CCS[1:0] Ý are
then left asserted until the next halt or stop grant
special cycle is occurs. When exiting the powerdown
state, the PCMC ignores the Secondary Cache Leadoff wait-states bit and executes a 3-2-2-2 read or
4-2-2-2 write in order to allow the SRAMs time to
power up. In the case of a read cycle, COE [1:0] Ý
are asserted in clock two as in the case of ordinary
read cycles.
When the SRAMs are powered down, the PCMC asserts CCS [1:0] Ý when performing a snoop cycle,
regardless of whether the cycle hits in the second
level cache. The PCMC then negates CCSÝ after
the snoop cycle is complete.
With a burst SRAM secondary cache, a halt or stop
grant special cycle from the CPU causes the PCMC
to negate CCSÝ and assert CADS [1:0] Ý, deselecting the SRAMs, placing them in a low power standby
mode. CCSÝ is then asserted and is left asserted by
the PCMC. Thus, when the first cycle is driven from
the CPU, the SRAMs sample ADSPÝ and CSÝ active, placing them in active mode and initiating the
first access.
If the SRAMs are required to service a snoop, they
are brought out of power-down when the PCMC asserts CADS [1:0] Ý. The PCMC always asserts
CADS [1:0] Ý with CCSÝ negated after a snoop cycle is complete, regardless of whether the SRAMs
were powered down prior to the snoop cycle.
5.2.3 SECOND LEVEL CACHE STANDBY
When the PCMC detects a halt or stop grant special
cycle from the CPU, it first places the second level
cache into the low power stand-by mode by deselecting the SRAMs and then generates a halt or stop
grant special cycle on PCI.
With a standard SRAM secondary cache, a halt or
stop grant special cycle from the CPU causes the
PCMC to negate CCS [1:0] Ý, deselecting the
SRAMs and placing them in a low power standby
mode. When the cache is in stand-by mode, the first
bus cycle from the CPU brings the cache out of
5.2.4 SNOOP CYCLES
For snoop operations, refer to Section 5.1, 82434LX
Cache.
5.2.5 FLUSH, FLUSH ACKNOWLEDGE, AND
WRITE-BACK SPECIAL CYCLES
For flush, flush acknowledge, and write-back special
cycles, refer to Section 5.1, 82434LX Cache.
103
82434LX/82434NX
6.0 DRAM INTERFACE
This section describes the DRAM interface for the
82434LX DRAM Interface (Section 6.1) and the
82434NX DRAM Interface (Section 6.2). The differences are in the following areas:
1. Increased maximum DRAM memory size to
512 MBytes. An extra address line (MA11) has
been added to the 82434NX.
2. Two additional RASÝ lines for a total of eight
(RAS [0:7] Ý.
3. Addition of 50 MHz host-bus optimized DRAM
timing sets. Thus, the 82434LX supports 60 and
66 MHz frequencies and the 82434NX supports
50, 60, and 66 MHz.
6.1 82434LX DRAM Interface
The 82434LX PCMC integrates a high performance
DRAM controller supporting from 2–192 MBytes of
main memory. The PCMC generates the RASÝ,
CASÝ, WEÝ and multiplexed addresses for the
DRAM array, while the data path to DRAM is provided by two 82433LX LBXs. The DRAM controller interface is fully configurable through a set of control
registers. Complete descriptions of these registers
are given in Section 3.0, Register Description. A brief
overview of the registers which configure the DRAM
interface is provided in this section.
The 82434LX controls a 64-bit memory array (72-bit
including parity) ranging in size from 2 MBytes up to
192 MBytes using industry standard 36-bit wide
memory modules with fast page-mode DRAMs. Both
single- and double-sided SIMMs are supported. The
eleven multiplexed address lines, MA [10:0] allow
the PCMC to support 256K x 36, 1M x 36, and
4M x 36 SIMMs. The PCMC has six RASÝ lines enabling the support of up to six rows of DRAM. Eight
CASÝ lines allow byte control over the array during
read and write operations. The PCMC supports 70
and 60 ns DRAMs. The PCMC DRAM interface is
synchronous to the CPU clock and supports page
mode accesses to efficiently transfer data in bursts
of four Qwords.
The DRAM interface of the PCMC is configured by
the DRAM Control Mode Register (offset 57h) and
the six DRAM Row Boundary (DRB) Registers (off-
104
sets 60h – 65h). The DRAM Control Mode Register
contains bits to configure the DRAM interface for
RASÝ modes and refresh options. In addition,
DRAM Parity Error Reporting and System Management RAM space can be enabled and disabled.
When System Management RAM is enabled, if
SMIACTÝ from the Pentium processor is not asserted, all CPU read and write accesses to SMM memory are directed to PCI. The SMRAM Space Register
at configuration space offset 72h provides additional
control over the SMRAM space. The six DRB Registers define the size of each row in the memory array,
enabling the PCMC to assert the proper RASÝ line
for accesses to the array.
CPU-to-Memory write posting and read-around-write
operations are enabled and disabled via the Host
Read/Write Buffer Control Register (offset 53h).
PCI-to-Memory write posting is enabled and disabled via the PCI Read/Write Buffer Control Register (offset 54h). PCI master reads from main memory
always result in the PCMC and LBXs reading the
requested data and prefetching the next seven
Dwords.
Seven Programmable Attribute Map (PAM) Registers (offsets 59h – 5Fh) are used to specify the
cacheability and read/write status of the memory
space between 512 KBytes and 1 MByte. Each PAM
Register defines a specific address area enabling
the system to selectively mark specific memory
ranges as cacheable, read-only, write-only, read/
write or disabled. When a memory range is disabled,
all CPU accesses to that range are directed to PCI.
Two other registers also affect the DRAM interface,
the Memory Space Gap Register (offsets 78h – 79h)
and the Frame Buffer Range Register (offsets 7Ch –
7Fh). The Memory Space Gap Register is used to
place a logical hole in the memory space between
1 MByte to 16 MBytes to accommodate memory
mapped ISA boards. The Frame Buffer Range Register, is used to map a linear frame buffer into the
Memory Space Gap or above main memory. When
enabled, accesses to these ranges are never directed to the DRAM interface, but are always directed to
PCI.
82434LX/82434NX
6.1.1 DRAM CONFIGURATIONS
Figure 42 illustrates a 12-SIMM configuration which
supports single-sided SIMMs. A row in the DRAM
array is made up of two SIMMs which share a common RASÝ line. SIMM0 and SIMM1 are connected
to RAS0Ý and therefore, comprise row 0. SIMM10
and SIMM11 form row 5. Within any given row, the
two SIMMs must be the same size. Among the six
rows, SIMM densities can be mixed in any order.
That is, there are no restrictions on the ordering of
SIMM densities among the six rows.
The low order LBX (LBXL) is connected to byte
lanes 5, 4, 1, and 0 of the host and memory data
buses, and the lower two bytes of the PCI AD bus.
The high order LBX (LBXH) is connected to byte
lanes 7, 6, 3, and 2 of the host and memory data
buses, and the upper two bytes of the PCI AD bus.
Thus, SIMMs connected to LBXL are connected to
CAS [5:4,1:0] Ý and SIMMs connected to LBXH are
connected to CAS [7:6, 3:2] Ý.
The MA [10:0] and WEÝ lines are externally buffered to drive the large capacitance of the memory
array. Three buffered copies of the MA [10:0] and
WEÝ signals are required to drive the six row array.
Figure 43 illustrates a 6-SIMM configuration that
supports either single- or double-sided SIMMs. In
this configuration, single- and double-sided SIMMs
can be mixed. For example, if single-sided SIMMs
are installed into the sockets marked SIMM0 and
SIMM1, then RAS0Ý is connected to the SIMMs
and RAS1Ý is not connected. Row 0 is then populated and row 1 is empty. Two double-sided SIMMs
could then be installed in the sockets marked
SIMM2 and SIMM3, populating rows 2 and 3.
6.1.2 DRAM ADDRESS TRANSLATION
The 82434LX multiplexed row/column address to
the DRAM memory array is provided by the
MA [10:0] signals. The MA [10:0] bits are derived
from the host address bus as defined by Table 12.
MA [10:0] are translated from the host address
A [24:3] for all memory accesses, except those targeted to memory that has been remapped as a result of the creation of a memory space gap in the
lower extended memory area. In the case of a cycle
targeting remapped memory, the least significant
bits come directly from the host address, while the
more significant bits depend on the memory space
gap start address, gap size, and the size of main
memory.
Table 12. DRAM Address Translation
Memory Address,
MA [10:0]
10
9
8
7
6
5
4
3
2
1
0
Row Address
A24
A22
A20
A19
A18
A17
A16
A15
A14
A13
A12
Column Address
A23
A21
A11
A10
A9
A8
A7
A6
A5
A4
A3
105
82434LX/82434NX
290479 – 51
NOTE:
The figure shows the connections for the 82434LX. For the 82434NX, there are two additional RAS lines (RAS[7:6] Ý)
and one additional address line (MA11).
Figure 42. 82434LX DRAM Configuration Supporting Single-Sided SIMMs
106
82434LX/82434NX
290479 – 52
NOTE:
The figure shows the connections for the 82434LX. For the 82434NX, there are two additional RAS lines (RAS[7:6] Ý)
and one additional address line (MA11).
Figure 43. 82434LX DRAM Configuration Supporting Single- or Double-Sided SIMMs
107
82434LX/82434NX
Table 14. Refresh Cycle Performance
6.1.3 CYCLE TIMING SUMMARY
The 82434LX PCMC DRAM performance is summarized in Table 13 for all CPU read and write cycles.
Table 13. CPU to DRAM Performance Summary
Refresh
Type
Hidden RASÝ only CASÝ before
Refresh Refresh
RASÝ
Single
12
13
14
Burst of Four
48
52
56
Burst,
x-4-4-4
Timing
Single,
x-4-4-4
Timing
Read Page Hit
7-4-4-4
7
Read Row Miss
11-4-4-4
11
Read Page Miss
14-4-4-4
14
Posted Write, WT L2
3-1-1-1
3
6.1.4.1 Read Page Hit
Posted Write, WB L2
4-1-1-1
4
Write Page Hit
12-4-4-4
12
Figure 44 depicts a CPU burst read page hit from
DRAM. The 82434LX PCMC decodes the CPU address as a page hit and drives the column address
onto the MA [10:0] lines. CAS [7:0] Ý are then asserted to cause the DRAMs to latch the column address
and begin the read cycle. CMR (CPU Memory Read)
is driven on the HIG [4:0] lines to enable the memory
data to host data path through the LBXs. The PCMC
advances the MA [1:0] lines through the Pentium
processor burst order, negating and asserting
CAS [7:0] Ý to read each Qword. The host data is
latched on the falling edge of MDLE, when
CAS [7:0] Ý are negated. The latch is opened again
when MDLE is sampled asserted by the LBXs. The
LBXs tri-state the host data bus when HIG [4:0]
change to NOPC and MDLE rises. A single read
page hit from DRAM is similar to the first read of this
sequence. The HIG [4:0] lines are driven to NOPC
when BRDYÝ is asserted.
Cycle Type
Write Row Miss
13-4-4-4
13
Write Page Miss
16-4-4-4
16
0-Active RASÝ
Mode Read
10-4-4-4
10
0-Active RASÝ
Mode Write
12-4-4-4
12
CPU writes to the CPU-to-Memory Posted Write
Buffer are completed at 3-1-1-1 when the second
level cache is configured for write-through mode and
4-1-1-1 when the cache is configured for write-back
mode. Table 14 shows the refresh performance in
CPU clocks.
108
6.1.4 CPU TO DRAM BUS CYCLES
This section describes the CPU-to-DRAM cycles for
the 82434LX.
82434LX/82434NX
290479 – 53
Figure 44. Burst DRAM Read Cycle-Page Hit
109
82434LX/82434NX
6.1.4.2 Read Page Miss
Figure 45 depicts a CPU burst read page miss from
DRAM. The 82434LX decodes the CPU address as
a page miss and switches from initially driving the
column address to driving the row address on the
MA [10:0] lines. RASÝ is then negated to precharge
the DRAMs and then asserted to cause the DRAMs
to latch the new row address. The PCMC then
switches the MA [10:0] lines to drive the column address and asserts CAS [7:0] Ý. CMR (CPU Memory
Read) is driven on the HIG [4:0] lines to enable the
memory data to host data path through the LBXs.
The PCMC advances the MA [1:0] lines through the
Pentium processor burst order, negating and asserting CAS [7:0] Ý to read each Qword. The host data is
latched on the falling edge of MDLE, when
CAS [7:0] Ý are negated. The latch is opened again
when MDLE is sampled asserted by the LBXs. The
LBXs tri-state the host data bus when HIG [4:0]
change to NOPC and MDLE rises. A single read
page miss from DRAM is similar to the first read of
this sequence. The HIG [4:0] lines are driven to
NOPC when BRDYÝ is asserted.
290479 – 54
Figure 45. DRAM Read Cycle-Page Miss
110
82434LX/82434NX
6.1.4.3 Read Row Miss
Figure 46 depicts a CPU burst read row miss from
DRAM. The 82434LX decodes the CPU address as
a row miss and switches from initially driving the column address to driving the row address on the
MA [10:0] lines. The RASÝ signal that was asserted
is negated and the RASÝ for the currently accessed
row is asserted. The PCMC then switches the
MA [10:0] lines to drive the column address and asserts CAS [7:0] Ý. CMR (CPU Memory Read) is driven on the HIG [4:0] lines to enable the memory data
to host data path through the LBXs. The PCMC advances the MA [1:0] lines through the Pentium processor burst order, negating and asserting
CAS[7:0] Ý to read each Qword. The host data is
latched on the falling edge of MDLE, when
CAS [7:0] Ý are negated. The latch is opened again
when MDLE is sampled asserted by the LBXs. The
LBXs tri-state the host data bus when HIG [4:0]
change to NOPC and MDLE rises. A single read row
miss from DRAM is similar to the first read of this
sequence. The HIG [4:0] lines are driven to NOPC
when BRDYÝ is asserted.
290479 – 55
Figure 46. Burst DRAM Read Cycle-Row Miss
111
82434LX/82434NX
6.1.4.4 Write Page Hit
Figure 47 depicts a CPU burst write page hit from
DRAM. The 82434LX decodes the CPU write cycle
as a DRAM page hit. The HIG [4:0] lines are driven
to PCMWQ to post the write to the LBXs. In the figure, the write cycle is posted to the CPU-to-Memory
Posted Write Buffer at 4-1-1-1. The write is posted at
4-1-1-1 when the second level cache is configured
for a write-back policy. The write is posted to DRAM
at 3-1-1-1 when the second level cache is config-
ured for a write-through policy. When the cycle is
decoded as a page hit, the PCMC asserts WEÝ and
drives the RCMWQ command on MIG [2:0] to enable
the LBXs to drive the first Qword of the write onto
the memory data lines. MEMDRV is then driven to
cause the LBXs to continue to drive the first Qword
for three more clocks. CAS [7:0] Ý are then negated
and asserted to perform the writes to the DRAMs as
the MA [1:0] lines advance through the Pentium
processor burst order. A single write is similar to the
first write of the burst sequence. MIG [2:0] are driven
to NOPM in the clock after CAS [7:0] Ý are asserted.
290479 – 56
Figure 47. Burst DRAM Write Cycle-Page Hit
112
82434LX/82434NX
6.1.4.5 Write Page Miss
Figure 48 depicts a CPU burst write page miss to
DRAM. The 82434LX decodes the CPU write cycle
as a DRAM page miss. The HIG [4:0] lines are driven
to PCMWQ to post the write to the LBXs. In the figure, the write cycle is posted to the CPU-to-Memory
Posted Write Buffer at 4-1-1-1. The write is posted at
4-1-1-1 when the second level cache is configured
for a write-back policy. The write is posted to DRAM
at 3-1-1-1 when the second level cache is configured for a write-through policy. When the cycle is
decoded as a page miss, the PCMC switches the
MA [10:0] lines from the column address to the row
address and asserts WEÝ. The PCMC drives the
RCMWQ command on MIG [2:0] to enable the LBXs
to drive the first Qword of the write onto the memory
data lines. MEMDRV is then driven to cause the
LBXs to continue to drive the first Qword. The RASÝ
signal for the currently decoded row is negated to
precharge the DRAMs. RASÝ is then asserted to
cause the DRAMs to latch the row address. The
PCMC then switches the MA [10:0] lines to the column address and asserts CAS [7:0] Ý to initiate the
first write. CAS [7:0] Ý are then negated and asserted to perform the writes to the DRAMs as the
MA [1:0] lines advance through the Pentium processor burst order. A single write is similar to the first
write of the burst sequence. MIG [2:0] are driven to
NOPM in the clock after CAS [7:0] Ý are asserted.
290479 – 57
Figure 48. Burst DRAM Write Cycle-Page Miss
113
82434LX/82434NX
6.1.4.6 Write Row Miss
Figure 49 depicts a CPU burst write row miss to
DRAM. The 82434LX decodes the CPU write cycle
as a DRAM row miss. The HIG [4:0] lines are driven
to PCMWQ to post the write to the LBXs. In the figure, the write cycle is posted to the CPU-to-Memory
Posted Write Buffer at 4-1-1-1. The write is posted at
4-1-1-1 when the second level cache is configured
for a write-back policy. The write is posted to DRAM
at 3-1-1-1 when the second level cache is configured for a write-through policy. When the cycle is
decoded as a row miss, the PCMC negates the already active RASÝ signal, switches the MA [10:0]
lines from the column address to the row address
and asserts the RASÝ signal for the currently decoded row. The PCMC asserts WEÝ and drives the
RCMWQ command on MIG [2:0] to enable the LBXs
to drive the first Qword of the write onto the memory
data lines. MEMDRV is then driven to cause the
LBXs to continue to drive the first Qword. The PCMC
then switches the MA [10:0] lines to the column address and asserts CAS [7:0] Ý to initiate the first
write. CAS [7:0] Ý are then negated and asserted to
perform the writes to the DRAMs as the MA [1:0]
lines advance through the Pentium processor burst
order. A single write is similar to the first write of the
burst sequence. MIG[2:0] are driven to NOPM in the
clock after CAS [7:0] Ý are asserted.
290479 – 58
Figure 49. Burst DRAM Write Cycle-Row Miss
114
82434LX/82434NX
6.1.4.7 Read Cycle, 0-Active RASÝ Mode
When in 0-active RASÝ mode, every CPU cycle to
DRAM results in a RASÝ and CASÝ sequence.
RASÝ is always negated after a cycle completes.
Figure 50 depicts a CPU burst read cycle from
DRAM where the 82434LX is configured for 0-active
RASÝ mode. When in 0-active RASÝ mode, the
PCMC defaults to driving the row address on the
MA [10:0] lines. The PCMC asserts the RASÝ signal
for the currently decoded row causing the DRAMs to
latch the row address. The PCMC then switches the
MA[10:0] lines to drive the column address and asserts CAS [7:0] Ý. CMR (CPU Memory Read) is driv-
en on the HIG [4:0] lines to enable the memory data
to host data path through the LBXs. The PCMC advances the MA [1:0] lines through the Pentium processor burst order, negating and asserting
CAS [7:0] Ý to read each Qword. The host data is
latched on the falling edge of MDLE, when
CAS [7:0] Ý are negated. The latch is opened again
when MDLE is sampled asserted by the LBXs. The
LBXs tri-state the host data bus when HIG [4:0]
change to NOPC and MDLE rises. A single read row
miss from DRAM is similar to the first read of this
sequence. The HIG [4:0] lines are driven to NOPC
when BRDYÝ is asserted. RASÝ is negated with
CAS [7:0] Ý.
290479 – 59
Figure 50. Burst DRAM Read Cycle, 0-Active RASÝ Mode
115
82434LX/82434NX
6.1.4.8 Write Cycle, 0-Active RASÝ Mode
When in 0-active RASÝ mode, every CPU cycle to
DRAM results in a RASÝ and CASÝ sequence.
RASÝ is always negated after a cycle completes.
Figure 51 depicts a CPU Burst Write Cycle to DRAM
where the 82434LX is configured for 0-active RASÝ
mode. The HIG [4:0] lines are driven to PCMWQ to
post the write to the LBXs. In the figure, the write
cycle is posted to the CPU-to-Memory Posted Write
Buffer at 4-1-1-1. The write is posted at 4-1-1-1
when the second level cache is configured for a
write-back policy. The write is posted to DRAM at
3-1-1-1 when the second level cache is configured
for a write-through policy. When in 0-active RASÝ
mode, the PCMC defaults to driving the row address
on the MA [10:0] lines. The PCMC asserts the RASÝ
signal for the currently decoded row causing the
DRAMs to latch the row address. The PCMC asserts
WEÝ and drives the RCMWQ command on
MIG [2:0] to enable the LBXs to drive the first Qword
of the write onto the memory data lines. MEMDRV is
then driven to cause the LBXs to continue to drive
the first Qword. The PCMC then switches the
MA [10:0] lines to the column address and asserts
CAS [7:0] Ý to initiate the first write. CAS [7:0] Ý are
then negated and asserted to perform the writes to
the DRAMs as the MA [1:0] lines advance through
the Pentium processor burst order. A single write is
similar to the first write of the burst sequence.
MIG [2:0] are driven to NOPM in the clock after
CAS [7:0] are asserted.
290479 – 60
Figure 51. Burst DRAM Write Cycle, 0-Active RASÝ Mode
116
82434LX/82434NX
6.1.5 REFRESH
The refresh of the DRAM array can be performed by
either using RASÝ-only or CASÝ-before-RASÝ refresh cycles. When programmed for CASÝ-beforeRASÝ refresh, hidden refresh cycles are initiated
when possible. RASÝ only refresh can be used with
any type of second level cache configuration (i.e., no
second level cache is present, or either a burst
SRAM or standard SRAM second level cache is implemented). CASÝ-before-RASÝ refresh can be enabled when either no second level cache is present
or a burst SRAM second level cache is implemented. CASÝ-before-RASÝ refresh should not be used
when a standard SRAM second level cache is implemented. The timing of internally generated refresh
cycles is derived from HCLK and is independent of
any expansion bus refresh cycles.
The DRAM controller contains an internal refresh
timer which periodically requests the refresh control
logic to perform either a single refresh or a burst of
four refreshes. The single refresh interval is 15.6 ms.
The interval for burst of four refreshes is four times
the single refresh interval, or 62.4 ms. The PCMC is
configured for either single or burst of four refresh
and either RASÝ-only or CASÝ-before-RASÝ refresh via the DRAM Control Register (offset 57h).
To minimize performance impact, refresh cycles are
partially deferred until the DRAM interface is idle.
The deferment of refresh cycles is limited by the
DRAM maximum RASÝ low time of 100 ms. Refresh
cycles are initiated such that the RASÝ maximum
low time is never violated.
Hidden refresh cycles are run whenever all eight
CASÝ lines are active when the refresh cycle is internally requested. Normal CASÝ-before-RASÝ refresh cycles are run whenever the DRAM interface is
idle when the refresh is requested, or when any subset of the CASÝ lines is inactive as the refresh is
internally requested.
To minimize the power surge associated with refreshing a large DRAM array the DRAM interface
staggers the assertion of the RASÝ signals during
both CASÝ-before-RASÝ and RASÝ-only refresh
cycles. The order of RASÝ edges is dependent on
which RASÝ was most recently asserted prior to the
refresh sequence. The RASÝ that was active will be
the last to be activated during the refresh sequence.
All RAS [5:0] Ý lines are negated at the end of refresh cycles, thus, the first DRAM cycle after a refresh sequence is a row miss.
6.1.5.1 RASÝ-Only Refresh-Single
Figure 52 depicts a RASÝ-only refresh cycle when
the 82434LX is programmed for single refresh cycles. The diagram shows a CPU read cycle completing as the refresh timing inside the PCMC generates
a refresh request. The refresh address is driven on
the MA [10:0] lines. Since the CPU cycle was to row
0, RAS0Ý is negated. RAS1Ý is the first to be asserted. RAS2Ý through RAS5Ý are then asserted
sequentially while RAS0Ý is driven high, precharging the DRAMs in row 0. RAS0Ý is then asserted
after RAS5Ý. Each RASÝ line is asserted for six
host clocks.
117
82434LX/82434NX
290479 – 61
Figure 52. RASÝ Only Refresh-Single
118
82434LX/82434NX
6.1.5.2 CASÝ-before-RASÝ Refresh-Single
Figure 53 depicts a CASÝ-before-RASÝ refresh cycle when the 82434LX is programmed for single refresh cycles. The diagram shows a CPU read cycle
completing as the refresh timing inside the PCMC
generates a refresh request. The CPU read cycle is
less than a Qword, therefore a hidden refresh is not
initiated. After the CPU read cycle completes, all of
the RASÝ and CASÝ lines are negated. The PCMC
then asserts CAS[7:0] Ý and then sequentially asserts the RASÝ lines, starting with RAS1Ý since
RAS0Ý was the last RASÝ line asserted. Each
RASÝ line is asserted for six clocks.
290479 – 62
Figure 53. CASÝ-before-RASÝ Refresh-Single
119
82434LX/82434NX
6.1.5.3 Hidden Refresh-Single
Figure 54 depicts a hidden refresh cycle which takes
place after a DRAM read page hit cycle. The diagram shows a CPU read cycle completing as the
refresh timing inside the 82434LX generates a refresh request. The CPU read cycle is an entire
Qword, therefore a hidden refresh is initiated. After
the CPU read cycle completes, RASÝ is negated,
but all eight CASÝ lines remain asserted. The
PCMC then sequentially asserts the RASÝ lines,
starting with RAS1Ý since RAS0Ý was the last active RASÝ line. Each RASÝ line is asserted for six
clocks.
290479 – 63
Figure 54. Hidden Refresh-Single
120
82434LX/82434NX
5. Modified MA [11:0] timing to provide more
MA [11:0] setup time to CAS [7:0] Ý assertion.
6.2 82434NX DRAM Interface
This section describes the 82434NX DRAM interface. Changes in the 82430NX PCIset from the
82430 PCIset include:
6.2.1 DRAM ADDRESS TRANSLATION
The MA [11:0] lines are translated from the host address lines A [26:3] for all memory accesses, except
those targeted to memory that has been remapped
as a result of the creation of a memory space gap in
the lower extended memory area. In the case of a
cycle targeting remapped memory, the least significant bits come directly from the host address, while
the more significant bits depend on the memory
space gap start address, gap size, and the size of
main memory.
1. Increased maximum DRAM memory size to
512 MBytes. The 82430NX PCIset increases the
maximum memory array size from 192 MBytes to
512 MBytes.
2. Two additional row address lines (RAS [7:6] Ý) for
a total of eight (RAS [7:0] Ý).
3. Addition of 50 MHz host-bus optimized DRAM
timing sets.
4. Three additional registers are added to support
the increased memory sizeDRAM Row Boundary
Registers 6 and 7 (DRB [7:6] ) and the DRAM
Row Boundary Extension (DRBE) Register.
Table 15. DRAM Address Translation
Memory Address
MA [11:0]
11
10
9
8
7
6
5
4
3
2
1
0
Column Address
A25
A23
A21
A11
A10
A9
A8
A7
A6
A5
A4
A3
Row Address
A26
A24
A22
A20
A19
A18
A17
A16
A15
A14
A13
A12
121
82434LX/82434NX
6.2.2 CYCLE TIMING SUMMARY
The 82434NX PCMC DRAM performance for
50 MHz Host bus clock is summarized in Table 13
for all CPU read and write cycles. The 60/66 MHz
MA [11:0] timings when in X-4-4-4 mode have one
difference from the 82434LX MA [11:0] timings. The
MA lines switch to the next address in the burst sequence one clock sooner than in the 82434LX, providing more MA [11:0] setup time to CAS [7:0] Ý assertion. The 60/66 MHz DRAM timings for write cycles have been improved by 1 clock for all leadoffs.
The 50 MHz timings shown below are selected by
HOF e 00, DBT e 11, RWS e 0 and CWS e 0.
Table 16. CPU to DRAM Performance Summary
for 50 MHz Host Bus Clock
Cycle Type
x-3-3-3 Timing(1)
Read (Page Hit/Row Miss/
Page Miss)
6/10/12-3-3-3
Posted Write
4-1-1-1
Write (Page Hit/Row Miss/
Page Miss)
10/11/13-3-3-3
0-Active RASÝ
Mode Reads
9-3-3-3
0-Active RASÝ
Mode Writes
9-3-3-3
NOTES:
1. Single cycle timings are identical to these leadoff
timings.
122
Table 17. Refresh Cycle Performance
(Independent of CPU frequency)
Hidden
Refresh
RASÝ Only
Refresh
CASÝBeforeRASÝ
Single
16
17
18
Burst of Four
64
68
72
Refresh
Type
6.2.3 CPU TO DRAM BUS CYCLES
In this section, all timing diagrams are for 50 MHz
DRAM timing, 1-Active RAS mode. The 60/66 MHz
MA [11:0] timings when in X-4-4-4 mode have one
difference from the 82434LX MA [11:0] timings. The
MA lines switch to the next address in the burst sequence one clock sooner than in the 82434LX. The
write cycle leadoffs are 1 clock earlier for 82430NX
than 82430 (the MIGs and CAS timings improved by
1 clock). The 0-Active RASÝ modes closely resemble the row miss cases. In 0-Active RASÝ mode,
RASÝ is asserted one clock sooner than is shown in
the row miss timing diagrams.
82434LX/82434NX
6.2.3.1 Burst DRAM Read Page Hit
Figure 55 depicts a CPU burst read page hit to
DRAM. The 82434NX decodes the CPU address as
a page hit and drives the column address onto the
MA [11:0] lines. CAS [7:0] Ý are then asserted for
two CLKs and negated for one CLK. CMR (CPU
Memory Read) is driven on the HIG [4:0] lines to enable the memory data to host data path through the
LBXs. The PCMC advances the MA [1:0] lines
through the processor burst order, negating and asserting CAS [7:0] Ý to read each Qword. The
MD[63:0] data is sampled with HCLK in the LBXs
when MDLE is asserted, and driven on the host bus
the following cycle to meet the setup time of the
CPU. BRDYÝ is then asserted. When MDLE is negated, the LBX continues to drive the latched
HD [63:0] to ensure that the data hold time to
CWE[7:0] Ý is met for standard SRAMs. The LBXs
tri-state the host data bus when HIG [4:0] change to
NOPC and MDLE rises. A single read page hit from
DRAM is similar to the first read of this sequence.
The HIG [4:0] lines are driven to NOPC when the last
BRDYÝ is asserted.
The diagram also shows the typical control signal
timing for a burst SRAM line fill operation. Note that
CCSÝ inactive will mask any new ADSÝ (caused by
the NAÝ assertion) to the burst SRAMs.
290479 – 64
Figure 55. Burst DRAM Read Cycle-Page Hit
123
82434LX/82434NX
6.2.3.2 Burst DRAM Read Page Miss
Figure 56 depicts a CPU to DRAM burst read page
miss cycle. The 82434NX decodes the CPU address
as a page miss and switches from initially driving the
column address to driving the row address on the
MA [11:0] lines. RASÝ is then negated to precharge
the DRAMs and then asserted to latch the new
DRAM row address. The PCMC then switches the
MA [11:0] lines to drive the column address and asserts CAS [7:0] Ý. CMR (CPU Memory Read) is driven on the HIG [4:0] lines to enable the memory data
to host data path through the LBXs. The PCMC ad-
vances the MA [1:0] lines through the microprocessor burst order, negating and asserting CAS [7:0] Ý
to read each Qword. The MD [63:0] data is sampled
with HCLK in the LBXs when MDLE is asserted, and
driven on the host bus the following cycle to meet
the setup time of the CPU. BRDYÝ is then asserted.
When MDLE is negated, the LBX continues to drive
the latched HD [63:0] to ensure that the data hold
time to CWE [7:0] Ý is met for standard SRAMs. The
LBXs tri-state the host data bus when HIG [4:0]
change to NOPC and MDLE rises. The HIG [4:0]
lines are driven to NOPC when the last BRDYÝ is
asserted.
290479 – 65
Figure 56. Burst DRAM Read Cycle-Page Miss
124
82434LX/82434NX
6.2.3.3 Burst DRAM Read Row Miss
Figure 57 depicts a CPU to DRAM burst read row
miss cycle. The 82434NX decodes the CPU address
as a row miss and switches from initially driving the
column address to driving the row address on the
MA [11:0] lines. The RASÝ signal that was asserted
is negated and the RASÝ for the currently accessed
row is asserted (RASÝ is asserted 1 clock earlier in
0-Active RASÝ Mode.) The PCMC then switches
the MA [11:0] lines to drive the column address and
asserts CAS [7:0] Ý. CMR (CPU Memory Read) is
driven on the HIG[4:0] lines to enable the memory
data to host data path through the LBXs. The PCMC
advances the MA [1:0] lines through the microproc-
essor burst order, negating and asserting
CAS [7:0] Ý to read each Qword. The MD [63:0] data
is sampled with HCLK in the LBXs when MDLE is
asserted, and driven on the host bus the following
cycle to meet the setup time of the CPU. BRDYÝ is
then asserted. When MDLE is negated, the LBX
continues to drive the latched HD [63:0] to ensure
that the data hold time to CWE [7:0] Ý is met for
standard SRAMs. The LBXs tri-state the host data
bus when HIG [4:0] change to NOPC and MDLE rises. A single read row miss from DRAM is similar to
the first read of this sequence. The HIG [4:0] lines
are driven to NOPC when the last BRDYÝ is
asserted.
290479 – 66
Figure 57. Burst DRAM Read Cycle-Row Miss
125
82434LX/82434NX
6.2.3.4 Burst DRAM Write Page Hit
Figure 58 depicts a CPU burst write page hit to
DRAM. The 82434NX decodes the CPU write cycle
as a DRAM page hit. The HIG [4:0] lines are driven
to PCMWQ to post the write to the LBXs. In the figure, the write cycle is posted to the CPU-to-Memory
Posted Write Buffer at 3-1-1-1. When the cycle is
decoded as a page hit, the PCMC asserts WEÝ and
drives the RCMWQ command on MIG [2:0] to enable
the LBXs to drive the first Qword of the write onto
the memory data lines. MEMDRV is then driven to
cause the LBXs to continue to drive the first Qword
for two more clocks. CAS[7:0] Ý are then negated
and asserted to perform the writes to the DRAMs as
the MA [1:0] lines advance through the Pentium
processor burst order. A single write is similar to the
first write of the burst sequence. The MIG [2:0] lines
are driven to NOPM in the clock when the last
CAS [7:0] Ý are asserted.
290479 – 67
Figure 58. Burst DRAM Write Page Miss
126
82434LX/82434NX
6.2.3.5 Burst DRAM Write Page Miss
Figure 59 depicts a CPU burst write page miss to
DRAM. The 82434NX decodes the CPU write cycle
as a DRAM page miss and drives the PCMWQ command [HIG [4:0] lines] to post the write data to the
LBXs. In the figure, the write cycle is posted to the
CPU-to-Memory Posted Write Buffer at 3-1-1-1.
When the cycle is decoded as a page miss, the
PCMC switches the MA [11:0] lines from the column
address to the row address and asserts WEÝ in
clock 4. The PCMC drives the RCMWQ command
on MIG[2:0] to enable the LBXs to drive the first
Qword of the write onto the memory data lines.
MEMDRV is then driven to cause the LBXs to continue to drive the first Qword. The RASÝ signal for
the currently decoded row is negated to precharge
the DRAMs. RASÝ is then asserted to cause the
DRAMs to latch the row address. The PCMC then
switches the MA [11:0] lines to the column address
and asserts CAS [7:0] Ý to initiate the first write.
CAS [7:0] Ý are then negated and asserted to perform the writes to the DRAMs as the MA [1:0] lines
advance through the Pentium processor burst order.
A single write is similar to the first write of the burst
sequence. The MIG [2:0] lines are driven to NOPM in
the clock when the last CAS[7:0] Ý are asserted.
290479 – 68
Figure 59. Burst DRAM Write Cycle-Page Miss
127
82434LX/82434NX
6.2.3.6 Burst DRAM Write Row Miss
Figure 60 depicts a CPU burst write row miss to
DRAM. The 82434NX decodes the CPU write cycle
as a DRAM row miss and the HIG [4:0] lines are driven to PCMWQ to post the write data into LBXs.
When the cycle is decoded as a row miss, the PCMC
negates the already active RASÝ signal, switches
the MA [11:0] lines from the column address to the
row address and asserts the RASÝ signal for the
currently decoded row. The PCMC asserts WEÝ
and drives the RCMWQ command on MIG [2:0] to
enable the LBXs to drive the first Qword of the write
onto the memory data lines. MEMDRV is then driven
to cause the LBXs to continue to drive the first
Qword. The PCMC then switches the MA[11:0] lines
to the column address and asserts CAS [7:0] Ý to
initiate the first write. CAS [7:0] Ý are then negated
and asserted to perform the writes to the DRAMs as
the MA [1:0] lines advance through the microprocessor burst order. A single write is similar to the first
write of the burst sequence. The MIG [2:0] lines are
driven to NOPM in the clock when the last
CAS [7:0] Ý are asserted.
290479 – 69
Figure 60. Burst DRAM Write Cycle-Row Miss
128
82434LX/82434NX
6.2.4 REFRESH
The refresh of the DRAM array can be performed by
either using RASÝ-only or CASÝ-before-RASÝ
refresh cycles. When programmed for CASÝbefore-RASÝ refresh, hidden refresh cycles are
initiated when possible. The timing of internally generated refresh cycles is derived from HCLK and is
independent of any expansion bus refresh cycles.
The DRAM controller contains an internal refresh
timer which periodically requests the refresh control
logic to perform either a single refresh or a burst of
four refreshes. The single refresh interval is 15.6 ms.
The interval for burst of four refreshes is four times
the single refresh interval, or 62.4 ms. The PCMC is
configured for either single or burst of four refresh
and either RASÝ-only or CASÝ-before RASÝ refresh via the DRAM Control Register (offset 57h).
To minimize performance impact, refresh cycles are
partially deferred until the DRAM interface is idle.
Refresh cycles are initiated such that the RASÝ
maximum active time is never violated.
Hidden refresh cycles are run whenever all eight
CASÝ lines are active at the end of a read transaction when the refresh cycle is internally requested.
Normal CASÝ-before-RASÝ refresh cycles are run
whenever the DRAM interface is idle when the refresh is requested, or when any subset of the CASÝ
lines is inactive as the refresh is internally requested.
To minimize the power surge for refreshing a large
DRAM array, the DRAM interface staggers the assertion and negation of the RASÝ signals during
both CASÝ-before-RASÝ and RASÝ-only refresh
cycles. The order of RASÝ edges is dependent on
which RASÝ was most recently asserted prior to the
refresh sequence. The RASÝ that was active will be
the last to be activated during the refresh sequence.
All RAS[7:0] Ý lines are negated at the end of refresh cycles, making the first DRAM cycle after a
refresh sequence a row miss.
6.2.4.1 RASÝ-Only RefreshÐSingle
Figure 61 depicts a RASÝ-only refresh cycle when
the 82434NX is programmed for single refresh cycles. The diagram shows a cycle completing as the
refresh timer inside the PCMC generates a refresh
request. The refresh address is driven on the
MA [11:0] lines. Since the cycle was to row 0,
RAS0Ý is negated. RAS1Ý is the first to be asserted. RAS2Ý through RAS7Ý are then asserted sequentially while RAS0Ý is driven high, precharging
the DRAMs in row 0. RAS0Ý is then asserted after
RAS7Ý. Each RASÝ line is asserted for eight host
clocks.
290479 – 70
Figure 61. RASÝ-Only RefreshÐSingle
129
82434LX/82434NX
6.2.4.2 CASÝ-before-RASÝ RefreshÐSingle
Figure 62 depicts a CASÝ-before-RASÝ refresh
cycle when the 82434NX is programmed for single
refresh cycles. The diagram shows a write cycle
completing as the refresh timer inside the PCMC
generates a refresh request. The cycle is less than a
Qword, therefore a hidden refresh is not initiated.
After the cycle completes, all of the RASÝ and
CASÝ lines are negated. The PCMC then asserts
CAS[7:0] Ý and then sequentially asserts the RASÝ
lines, starting with RAS1Ý since RAS0Ý was the
last RASÝ line asserted. Each RASÝ line is asserted for eight clocks.
290479 – 71
Figure 62. CASÝ-Before-RASÝ RefreshÐSingle
130
82434LX/82434NX
6.2.4.3 Hidden Refresh-Single
Figure 63 depicts a hidden refresh cycle which takes
place after a DRAM read page hit cycle. The diagram shows a read cycle completing as the refresh
timing inside the 82434NX PCMC generates a refresh request. The cycle is an entire Qword; there-
fore, a hidden refresh is initiated. After the cycle
completes, RASÝ is negated, but all eight CASÝ
lines remain asserted. The PCMC then sequentially
asserts the RASÝ lines, starting with RAS1Ý since
RAS0Ý was the last active RASÝ line. Each RASÝ
line is asserted for eight clocks.
290479 – 72
Figure 63. Hidden RefreshÐSingle
131
82434LX/82434NX
7.0 PCI INTERFACE
The description in this section applies to both the
82434LX and 82434NX.
7.1 PCI Interface Overview
The PCMC and LBXs form a high performance
bridge from the Pentium processor to PCI and from
PCI to main memory. During PCI-to-main memory
cycles, the PCMC and LBXs act as a target on the
PCI Bus, allowing PCI masters to read from and
write to main memory. During CPU cycles, the
PCMC acts as a PCI master. The CPU can then read
and write I/O, memory and configuration spaces on
PCI. When the CPU accesses I/O mapped and configuration space mapped PCMC registers, the PCMC
intercepts the cycles and does not forward them to
PCI. Although these CPU cycles do not result in a
PCI bus cycle, they are described in this section
since most of the PCMC internal registers are
mapped into PCI configuration space.
7.2 CPU-to-PCI Cycles
7.2.1 CPU WRITE TO PCI
Figure 64 depicts a series of CPU memory writes
which are posted to PCI. The CPU initiates the
cycles by asserting ADSÝ and driving the memory
address onto the host address lines. The PCMC
asserts NAÝ in the clock after ADSÝ allowing the
Pentium processor to drive another cycle onto the
host bus two clocks later. The PCMC decodes the
memory address and drives PCPWL on the HIG [4:0]
lines, posting the host address bus and the low
Dword of the data bus to the LBXs. The PCMC asserts BRDYÝ, terminating the CPU cycle with one
wait state. Since NAÝ is asserted in the second
132
clock of the first cycle, the Pentium processor does
not insert an idle cycle after this cycle completes,
but immediately drives the next cycle onto the bus.
Thus, the Pentium processor maximum Dword write
bandwidth of 89 MBytes/second is achieved during
back-to-back Dword writes cycles. Each of the following write cycles is posted to the LBXs in three
clocks.
In this example, the PCMC is parked on PCI and
therefore, does not need to arbitrate for the bus.
When parked, the PCMC drives the SCPA command
on the PIG[3:0] lines and asserts DRVPCI, causing
the host address lines to be driven on the PCI
AD [31:0] lines. After the write is posted, the PCMC
drives the DCPWA command on the PIG [3:0] lines
to drive the previously posted address onto the
AD [31:0] lines. The PCMC then drives DCPWD onto
the PIG [3:0] lines, to drive the previously posted
write data onto the AD [31:0] lines. As this is occurring on PCI, the second write cycle is being posted
on the host bus. In this case, the second write is to a
sequential and incrementing address. Thus, the
PCMC leaves FRAMEÝ asserted, converting the
write cycle into a PCI burst cycle. The PCMC continues to drive the DCPWD command on the PIG [3:0]
lines. The LBXs advance the posted write buffer
pointer to point to the next posted Dword when
DCPWD is sampled on PIG [3:0] and TRDYÝ is
sampled asserted. Therefore, if the target inserts a
wait-state by negating TRDYÝ, the LBXs continue
to drive the data for the current transfer. The remaining writes are posted on the host bus, while the
PCMC and LBXs complete the writes on PCI.
CPU I/O write cycles to PCI differ from the memory
write cycle described here in that I/O writes are never posted. BRDYÝ is asserted to terminate the cycle
only after TRDYÝ is sampled asserted, completing
the cycle on PCI.
82434LX/82434NX
290479 – 73
Figure 64. CPU Memory Writes to PCI
7.3 Register Access Cycles
The PCMC contains two registers which are mapped
into I/O space, the Configuration Space Enable
Register (I/O port CF8h) and the Turbo-Reset Control Register (I/O port CF9h). All other internal
PCMC configuration registers are mapped into PCI
configuration space. Configuration space must be
enabled by writing a non-zero value to the Key field
in the CSE Register before accesses to these registers can occur. These registers are mapped to locations C000h through C0FFh in PCI configuration
space. If the Key field is programmed with 0h, CPU
I/O cycles to locations C000h through CFFFh are
forwarded to PCI as ordinary I/O cycles. Externally,
accesses to the I/O mapped registers and the configuration space mapped registers use the same bus
transfer protocol. Only the PCMC internal decode of
the cycle differs. NAÝ is never asserted during
PCMC configuration register or PCI configuration
register access cycles. See Section 3.2, PCI Configuration Space Mapped Registers for details on the
PCMC configuration space mapping mechanism.
133
82434LX/82434NX
7.3.1 CPU WRITE CYCLE TO PCMC INTERNAL
REGISTER
A write to an internal PCMC register (either CSE
Register, TRC Register or a configuration spacemapped register) is shown in Figure 65. The cycle
begins with the address, byte enables and status
signals (W/RÝ, D/CÝ and M/IOÝ) being driven to
a valid state indicating an I/O write to either CF8h to
access the CSE register, CF9h to access the TRC
Register or C0XXh when configuration space is enabled to access a PCMC internal configuration register. The PCMC decodes the cycle and asserts
AHOLD to tri-state the CPU address lines. The
PCMC signals the LBXs to copy either the upper
Dword or the lower Dword of the data bus onto the
address lines. The PCMC makes the decision on
which Dword to copy based on the BE [7:0] Ý lines.
The HIG [4:0] lines are driven to DACPYH or
DACPYL depending on whether the lower Dword of
the data bus or the upper Dword of the data bus
needs to be copied onto the address bus. The LBXs
sample the HIG [4:0] command, and drive the data
onto the address lines. The PCMC samples the
A [31:0] lines on the second rising edge of HCLK
after the LBXs begin driving the data. Finally, the
PCMC negates AHOLD and asserts BRDYÝ, terminating the cycle.
If the write is to the CSE Register and the Key field is
programmed to 0000b then configuration space is
disabled. If the Key field is programmed to a nonzero value then configuration space is enabled.
290479 – 75
Figure 65. CPU Write to a PCMC Configuration Register
134
82434LX/82434NX
7.3.2 CPU READ FROM PCMC INTERNAL
REGISTER
A read from an internal PCMC register (either CSE
Register, TRC Register or a configuration spacemapped register) is shown in Figure 66. The I/O
read cycle is from either CF8h to access the CSE
register, CF9h to access the TRC Register or C0XXh
when configuration space is enabled to access a
configuration space-mapped register. The PCMC
decodes the cycle and asserts AHOLD to tri-state
the CPU address lines. The PCMC then drives the
contents of the addressed register onto the A [31:0]
lines. One byte is enabled on each rising HCLK edge
for four consecutive clocks. The PCMC signals the
LBXs that the current cycle is a read from an internal
PCMC register by issuing the ADCPY command to
the LBXs over the HIG [4:0] lines. The LBXs sample
the HIG [4:0] command and copy the address lines
onto the data lines. Finally, the PCMC negates
AHOLD, and asserts BRDYÝ terminating the cycle.
290479 – 76
Figure 66. CPU Read from PCMC Configuration Register
135
82434LX/82434NX
7.3.3 CPU WRITE TO PCI DEVICE
CONFIGURATION REGISTER
In order to write to or read from a PCI device configuration register the Key field in the CSE register
must be programmed to a non-zero value, enabling
configuration space. When configuration space is
enabled, PCI device configuration registers are accessed by CPU I/O accesses within the range of
CnXXh where each PCI device has a unique nonzero value of n. This allows a separate configuration
space for each of 15 devices on PCI. Recall that
when configuration space is enabled, the PCMC
configuration registers are mapped into I/O ports
C000h through C0FFh.
A write to a PCI device configuration register is
shown in Figure 67. The PCMC internally latches the
host address lines and byte enables. The PCMC asserts AHOLD to tri-state the CPU address bus and
drives the address lines with the translated address
for the PCI configuration cycle. The translation is described in Section 3.2, PCI Configuration Space
Mapped Registers. On the HIG [4:0] lines, the PCMC
signals the LBXs to latch either the upper Dword of
136
the host data bus or the lower Dword of the host
data bus to be driven onto PCI during the data phase
of the PCI cycle. On the PIG [3:0] lines, the PCMC
signals the LBXs to drive the latched host address
lines on the PCI AD [31:0] lines. The upper two bytes
of the address lines are used during configuration as
IDSEL signals for the PCI devices. The IDSEL pin on
each PCI device is connected to one of the
AD [31:17] lines.
The PCMC drives the command for a configuration
write (1011) onto the C/BE [3:0] Ý lines and asserts
FRAMEÝ for one PCI clock. The PCMC drives the
PIG [3:0] lines signaling the LBXs to drive the contents of the PCI write buffer onto the PCI AD [31:0]
lines. This command is driven for only one PCI clock
before returning to the SCPA command on the
PIG [3:0] lines. The LBXs continue to drive the
AD [31:0] lines with the valid write data as long as
DRVPCI is asserted. The PCMC then asserts
IRDYÝ and waits until sampling the TRDYÝ signal
active. When TRDYÝ is sampled asserted, the
PCMC negates DRVPCI tri-stating the LBX AD [31:0]
lines. BRDYÝ is asserted for one clock to terminate
the CPU cycle.
82434LX/82434NX
290479 – 77
Figure 67. CPU Write to PCI Device Configuration Register
137
82434LX/82434NX
7.3.4 CPU READ FROM PCI DEVICE
CONFIGURATION REGISTER
In order to write to or read from a PCI device configuration register the Key field in the CSE register
must be programmed to a non-zero value, enabling
configuration space. When configuration space is
enabled, PCI device configuration registers are accessed by CPU I/O accesses within the range of
CnXXh where each PCI device has a unique nonzero value of n. This allows a separate configuration
space for each of 15 devices on PCI. Recall that
when configuration space is enabled, the PCMC
configuration registers occupy I/O addresses
C0XXH.
A CPU read from a PCI device configuration register
is shown in Figure 68. The PCMC internally latches
the host address lines and byte enables. The PCMC
asserts AHOLD to tri-state the CPU address bus.
The PCMC drives the address lines with the translat-
138
ed address for the PCI configuration cycle. The
translation is described in Section 3.2, PCI Configuration Space Mapped Registers. On the PIG [3:0]
lines, the PCMC signals the LBXs to drive the
latched host address lines on the PCI AD [31:0]
lines. The upper two bytes of the address lines are
used during configuration as IDSEL signals for the
PCI devices. The IDSEL pin on each PCI device is
connected to one of the AD [31:17] lines.
The PCMC drives the command for a configuration
read (1010) onto the C/BE [3:0] Ý lines and asserts
FRAMEÝ for one PCI clock. The PCMC drives the
PIG [3:0] lines signaling the LBXs to latch the data
on the PCI AD [31:0] lines into the CPU-to-PCI first
read prefetch buffer. The PCMC then drives the
HIG [4:0] lines signaling the LBXs to drive the data
from the buffer onto the host data lines. The PCMC
asserts IRDYÝ and waits until sampling TRDYÝ active. After TRDYÝ is sampled active, BRDYÝ is asserted for one clock to terminate the CPU cycle.
82434LX/82434NX
290479 – 78
Figure 68. CPU Read from PCI Device Configuration Register
139
82434LX/82434NX
During system initialization, the CPU typically attempts to read from the configuration space of all 15
possible PCI devices to detect the presence of the
devices. If no device is present, DEVSELÝ is not be
asserted and the cycle is terminated, returning
FF . . . FFh to the CPU. Figure 69 depicts an
attempted read from a configuration register of a
non-existent device. If no device responds then the
PCMC aborts the cycle and sends the DRVFF command over the HIG[4:0] lines causing the LBXs to
drive FF . . . FFh onto the host data lines.
290479 – 79
Figure 69. CPU Attempted Configuration Read from Non-Existent PCI Device
140
82434LX/82434NX
7.4 PCI-to-Main Memory Cycles
7.4.1 PCI MASTER WRITE TO MAIN MEMORY
Figure 70 depicts a PCI master burst write to main
memory. The PCI master begins by driving the address on the AD [31:0] lines and asserting FRAMEÝ.
Upon sampling FRAMEÝ active, the PCMC drives
the LCPA command on the PIG [3:0] lines causing
the LBXs to retain the address that was latched on
the previous PCLK rising edge. The PCMC then
samples MEMCSÝ active, indicating that the cycle
is directed to main memory. The PCMC drives the
PPMWA command on the PIG [3:0] lines to move
the latched PCI address into the write buffer address
register. The PCMC then drives the DPWA command on the HIG [4:0] lines enabling the LBXs to
drive the PCI master write address onto the host
address bus. The PCMC asserts EADSÝ to initiate a
first level cache snoop cycle and simultaneously begins an internal second level cache snoop cycle.
Since the snoop is a result of a PCI master write,
INV is asserted with EADSÝ. HITMÝ remains negated and the snoop either hits an unmodified line or
misses in the second level cache, thus no write-back
cycles are required. If the snoop hit an unmodified
line in either the first or second level cache, the line
is invalidated. The cycle is immediately forwarded to
the DRAM interface. The four posted Dwords are
written to main memory as two Qwords with two
CAS [7:0] Ý cycles. In this example, the DRAM interface is configured for X-3-3-3 write timing, thus each
CAS [7:0] Ý low pulse is two HCLKs in length.
The PCMC disconnects the cycle by asserting
STOPÝ when one of the two four-Dword-deep PCIto-Memory Posted Write Buffers is full. If the master
terminates the cycle before sampling STOPÝ asserted, then IRDYÝ, STOPÝ and DEVSELÝ are
negated when FRAMEÝ is sampled negated. If the
master intended to continue bursting, then the master negates FRAMEÝ when it samples STOPÝ asserted. IRDYÝ, STOPÝ and DEVSELÝ are then
negated one clock later.
141
82434LX/82434NX
290479 – 80
Figure 70. PCI Master Write to Main Memory-Page Hit
142
82434LX/82434NX
7.4.2 PCI MASTER READ FROM MAIN MEMORY
Figure 71 depicts a PCI master read from main
memory. The PCI master initiates the cycle by driving the read address on the AD [31:0] lines and asserting FRAMEÝ. The PCMC drives the LPMA command on the PIG [3:0] lines causing the LBXs to retain the address latched on the previous PCLK rising
edge. The PCMC drives the DPRA command on the
HIG [4:0] lines enabling the LBXs to drive the read
address onto the host address lines. The snoop cycle misses in the second level cache and either hits
an unmodified line or misses in the first level cache.
The cycle is then forwarded to the DRAM interface.
A read of four Qwords is performed. Each Qword is
posted in the PCI-Memory Read Prefetch Buffer.
The data is then driven onto PCI in an eight Dword
burst cycle. If the master terminates the cycle before
sampling STOPÝ, then IRDYÝ, STOPÝ and
DEVSELÝ are all negated after FRAMEÝ is sampled inactive. If the master intended to continue
bursting, then the master negates FRAMEÝ when it
samples STOPÝ asserted and IRDYÝ, STOPÝ and
DEVSELÝ are negated one clock later.
290479 – 81
Figure 71. PCI Master Read from Main Memory-Page Hit
143
82434LX/82434NX
8.0 SYSTEM CLOCKING AND RESET
8.1 Clock Domains
The 82434LX and 82434NX PCMCs and 82433LX
and 82433NX LBXs operate based on two clocks,
HCLK and PCLK. The CPU, second level cache, and
the DRAM interfaces operate based on HCLK. The
PCI interface timing is based on PCLK.
8.2 Clock Generation and Distribution
Figure 72 shows an example of the 82434LX and
82434NX PCMC host clock distribution in the CPU,
cache and memory subsystem. HCLK is distributed
to the CPU, PCMC, LBXs and the second level
cache SRAMs (in the case of a burst SRAM second
level cache).
The host clock originates from an oscillator which is
connected to the HCLKOSC input on the PCMC.
The PCMC generates six low skew copies of HCLK,
HCLKA–HCLKF. Figure 72 shows an example of a
host clock distribution scheme for a uni-processor
system. In this figure, clock loading is balanced with
each HCLK output driving two loads in the system.
Each clock output should drive a trace of length k
with stubs at the end of the trace of length l connecting to the two loads. The l and k parameters should
be matched for each of the six clock outputs to minimize overall system clock skew. One of the HCLK
outputs is used to clock the PCMC and the Pentium
processor. Because the clock driven to the PCMC
HCLKIN input and the Pentium processor CLK input
originates with the same HCLK output, clock skew
between the PCMC and the CPU can be kept lower
than between the PCMC and other system components. Another copy of HCLK is used to clock the
LBXs. A 256 KByte burst SRAM second level cache
can be implemented with eight 32 KByte x 9 synchronous SRAMs. The four remaining copies of
HCLK are used to clock the SRAMs. Each HCLK
output drives two SRAMs. A 512 KByte second level
cache is implemented with four 64 KByte x 18 synchronous SRAMs. Two of the four extra copies are
used to clock the SRAMs while the other two are
unused. Any one of the HCLK outputs can be used
to clock the PCMC and Pentium processor, the two
LBXs or any pair of SRAMs. All six copies are identical in drive strength.
Figure 73 depicts the PCI clock distribution.
290479 – 82
Figure 72. HCLK Distribution Example
144
82434LX/82434NX
290479 – 83
Figure 73. PCI Clock Distribution
The PCMC generates PCLKOUT with an internal
Phase Locked Loop (PLL). The PCLKOUT signal is
buffered using a single component to produce several low skew copies of PCLK to drive the LBXs and
other devices on PCI. One of the outputs of the
clock driver is directed back to the PCLKIN input on
the PCMC. The PLL locks the rising edges of
PCLKIN in phase with the rising edges of HCLKIN.
The PLL effectively compensates for the delay of
the external clock driver. The resulting PCI clock is
one half the frequency of HCLK. Timing for all of the
PCI interface signals is based on PCLKIN. All PCI
interface inputs are sampled on PCLKIN rising edges and all outputs transition as valid delays from
PCLKIN rising edges. Clock skew between the
PCLKIN pin on the PCMC and the PCLK pins on the
LBXs must be kept within 1.25 ns to guarantee proper operation of the LBXs.
pins, PLLAVDD, PLLAVSS and PLLAGND. These
power pins require a low noise supply. PLLAVDD,
PLLAVSS and PLLAGND must be connected to the
RC network shown in Figure 74.
8.3 Phase Locked Loop Circuitry
The resistance and capacitance values for the external PLL circuitry are listed below.
R1 e 10 KX g 5%
R2 e 150X g 5%
R3 e 33X g 5%
The 82434LX and 82434NX PCMCs each contain
two internal Phase Locked Loops (PLLs). Loop filters and power supply decoupling circuitry must be
provided externally. Figure 74 shows the PCMC connections to the external PLL circuitry.
One of the PCMC internal Phase Locked Loops
(PLL) locks onto the HCLKIN input. The PLL is used
by the PCMC in generating and sampling timing critical signals. An external loop filter is required. The
PLLARC1 and PLLARC2 pins connect to the external HCLK loop filter. Two resistors and a capacitor
form the loop filter. The loop filter circuitry should be
placed as close as possible to the PCMC loop filter
pins. The PLL also has dedicated power and ground
The second PCMC internal Phase Locked Loop
(PLL) locks the PCLKIN input in phase with the
HCLKIN input. The PLL is used by the PCMC to
keep the PCI clock in phase with the host clock. An
external loop filter is required. The PLLBRC1 and
PLLBRC2 pins connect to the external PCLK loop
filter. Two resistors and a capacitor form the loop
filter. The loop filter circuitry should be placed as
close as possible to the PCMC loop filter pins. The
PLL also has dedicated power and ground pins,
PLLBVDD, PLLBVSS and PLLBGND. These power
pins require a low noise supply. PLLBVDD,
PLLBVSS and PLLBGND must be connected to the
RC network shown in Figure 74.
C1 e 0.01 mF g 10%
C2 e 0.47 mF g 10%
An additional 0.01 mF capacitor in parallel with C2
will help to improve noise immunity.
145
82434LX/82434NX
290479 – 84
Figure 74. PCMC PLL Circuitry Connections
146
82434LX/82434NX
8.4 System Reset
Figure 75 shows the 82434LX and 82434NX PCMC
system reset connections. The 82434LX and
82434NX PCMC reset logic monitors PWROK and
generates CPURST, PCIRSTÝ and INIT.
When asserted, PWROK is an indicator to the PCMC
that VDD and HCLK have stabilized long enough for
proper system operation. CPURST is asserted to initiate hard reset. INIT is asserted to initiate soft reset.
PCIRSTÝ is asserted to reset devices on PCI.
Hard reset is initiated by the PCMC in response to
one of two conditions. First, hard reset is initiated
when power is first applied to the system. PWROK
must be driven inactive and must not be asserted
until 1 ms after VDD and HCLK have stabilized at
their AC and DC specifications. While PWROK is
negated, the 82434LX asserts CPURST and
PCIRSTÝ. PWROK can be asserted asynchronously. When PWROK is asserted, the 82434LX first ensures that it has been completely initialized before
negating CPURST and PCIRSTÝ. CPURST is negated synchronously to the rising edge of HCLK.
PCIRSTÝ is negated asynchronously.
290479 – 85
Figure 75. PCMC System Reset Logic
147
82434LX/82434NX
When PWROK is negated, the PCMC asserts
AHOLD causing the CPU to tri-state the host address lines. Address lines A [31:29] are sampled by
the PCMC 1 ms after the rising edge of PWROK.
The values sampled on A [31:30] are inverted inside
the PCMC and then stored in Configuration Register
52h bits 7 and 6. The A [31:30] strapping options are
depicted in Table 18.
Table 18. A [31:30] Strapping Options
A[31:30]
Configuration
Register 52h,
Bits[7:6]
11
00
Secondary
Cache Size
Not Populated
10
01
Reserved
01
10
256 KByte Cache
00
11
512 KByte Cache
Table 19. 82434LX Output and I/O Signal States
During Hard Reset
Signal
State
Signal
State
A [31:0]
Input
IRDYÝ
Input
AHOLD
High/Low
KENÝ
Undefined
BOFFÝ
High
MA [10:0]
Undefined
BRDYÝ
High
MDLE
High
CAA [6:3]
Undefined MEMACKÝ High-Z
CAB [6:3]
Undefined MIG [2:0]
Low
CADS [1:0] Ý High
NAÝ
High
CADV [1:0] Ý High
PAR
Input
CALE
High
PENÝ
High
CAS [7:0] Ý
High
PERRÝ
Input
COE [1:0] Ý
High
PLOCKÝ
Input
The value sampled on A29 is inverted inside the
PCMC and stored in the SRAM Type Bit (bit 5) in the
SCC Register. A28 is required to be pulled high for
compatibility with future versions of the PCMC.
CWE [7:0] Ý
High
PIG3
Low
C/BE [3:0] Ý
Input
PIG [2:0]
High
DEVSELÝ
Input
RAS [5:0] Ý High
The PCMC also initiates hard reset when the System
Hard Reset Enable bit in the Turbo-Reset Control
Register (I/O address CF9h) is set to 1 and the Reset CPU bit toggles from 0 to 1. The PCMC drives
CPURST and PCIRSTÝ active for a minimum of
1 ms.
DRVPCI
Low
REQÝ
High-Z
EADSÝ
High
SERRÝ
Input
Table 19 shows the state of all 82434LX PCMC
output and bi-directional signals during hard reset.
During hard reset both CPURST and PCIRSTÝ are
asserted. When the hard reset is due to PWROK
negation, AHOLD is asserted. The PCMC samples
the strapping options on the A [31:29] lines 1 ms after the rising edge of PWROK. When hard reset is
initiated via a write to the Turbo-Reset Control Register (I/O port CF9h) AHOLD remains negated
throughout the hard reset. Table 19 also applies to
the 82434NX, with the exception of the signals listed
in Section 8.5, 82434NX Reset Sequencing.
148
FRAMEÝ
Input
STOPÝ
Input
HIG [4:0]
Low
TRDYÝ
Input
INIT
Low
WEÝ
High
INV
Low
Soft reset is initiated by the PCMC in response to
one of two conditions. First, when the System Hard
Reset Enable bit in the TRC Register is reset to 0,
and the Reset CPU bit toggles from 0 to 1, the
PCMC initiates soft reset by asserting INIT for a minimum of 2 HCLKs. Second, the PCMC initiates a soft
reset upon detecting a shutdown cycle from the
CPU. In this case, the PCMC first broadcasts a shutdown special cycle on PCI and then asserts INIT for
a minimum of 2 HCLKs.
82434LX/82434NX
8.5 82434NX Reset Sequencing
When PWROK is negated, the 82434NX PCMC
drives the following signals lowÐBRDYÝ, NAÝ,
INV,
BOFFÝ,
KENÝ,
AHOLD,
EADSÝ,
PENÝ, CPURST, INIT, CALE, CADS [1:0] Ý,
CADV[1:0] Ý, CAA[6:3], CAB[6:3], COE[1:0] Ý,
CWE [7:0] Ý. HCLK [A:F] are driven as soon as the
3.3V supply is active. Note that CWE [7:0] Ý low prevents the second level cache data RAMs from driving the data bus, even though COE [1:0] Ý are also
driven low. Also, note that BOFFÝ driven low causes the CPU to tri-state all outputs to the 82434NX
PCMC and 82433NX LBX, except HITMÝ,
SMIACTÝ, and PCHKÝ. This minimizes the number
of signals that the CPU may drive to the PCMC when
the 3.3V supply is active and the 5V supply is not
active.
Figure 76 shows how the 82434NX sequences
CPURST and PCIRSTÝ in response to PWROK assertion.
Some PCI devices may drive 3.3V friendly signals
directly to 3.3V devices that are not 5V tolerant. If
such signals are powered from the 5V supply they
must be driven low when PCIRSTÝ is asserted.
Some of these signals may need to be driven high
before CPURST is negated. PCIRSTÝ is negated
1 ms before CPURST to allow time for this to occur.
290479 – 86
Figure 76. 82434NX Reset Sequencing at Power-Up
149
82434LX/82434NX
9.0 ELECTRICAL CHARACTERISTICS
NOTICE: This data sheet contains information on
products in the sampling and initial production phases
of development. The specifications are subject to
change without notice. Verify with your local Intel
Sales office that you have the latest data sheet before finalizing a design.
9.1 Absolute Maximum Ratings
Case Temperature under Bias ÀÀÀÀÀÀÀ0§ C to a 85§ C
Storage Temperature ÀÀÀÀÀÀÀÀÀÀ b 55§ C to a 150§ C
Voltage on Any Pin
with Respect to GroundÀÀÀÀÀ b 0.3 to VCC a 0.3V
Supply Voltage
with Respect to VSS ÀÀÀÀÀÀÀÀÀÀÀÀ b 0.3 to a 6.5V
Maximum Total Power Dissipation ÀÀÀÀÀÀÀÀÀÀÀ2.0W
*WARNING: Stressing the device beyond the ‘‘Absolute
Maximum Ratings’’ may cause permanent damage.
These are stress ratings only. Operation beyond the
‘‘Operating Conditions’’ is not recommended and extended exposure beyond the ‘‘Operating Conditions’’
may affect device reliability.
Maximum Power Dissipation, VCC3 ÀÀÀÀÀÀÀÀ470 mW
9.2 Thermal Characteristics
The Maximum total power dissipation in the
82434NX on the VCC and VCC3 pins is 2.0W. The
VCC3 pins may draw as much as 470 mW, however,
total power will not exceed 2.0W.
The 82434LX and 82434NX PCMCs are designed
for operation at case temperatures between 0§ C and
85§ C. The thermal resistances of the package are
given in Table 20.
Table 20. PCMC Package Thermal Resistance
Air Flow Meters/Second
(Linear Feet per Minute)
Parameter
0
(0)
0.5
(98.4)
1.0
(196.9)
2.0
(393.7)
5.0
(984.3)
iJA (§ C/Watt)
31
27
24.5
23
19
iJC (§ C/Watt)
8.6
9.3 82434LX DC Characteristics
Functional Operating Range (VCC e 5V g 5%; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Unit
Test
Conditions
b 0.3
0.8
V
Note 1, VCC e 4.75V
VIL1
Input Low Voltage
VIH1
Input High Voltage
2.2
VCC a 0.3
V
Note 1, VCC e 5.25V
VIL2
Input Low Voltage
b 0.3
1.35
V
Note 2, VCC e 4.75V
VIH2
Input High Voltage
3.85
VCC a 0.3
V
Note 2, VCC e 5.25V
VT1
Schmitt Trigger Threshold Voltage,
Falling Edge
0.7
1.35
V
Note 3, VCC e 5.0V
VT1 a
Schmitt Trigger Threshold Voltage,
Falling Edge
1.4
2.2
V
Note 3, VCC e 5.0V
VH1
Hysteresis Voltage
0.3
1.2
V
Note 3, VCC e 5.0V
VT2b
Schmitt Trigger Threshold Voltage,
Falling Edge
1.25
2.3
V
Note 3, VCC e 5.0V
VT2 a
Schmitt Trigger Threshold Voltage,
Rising Edge
2.3
3.7
V
Note 3, VCC e 5.0V
VH2
Hysterersis Voltage
0.3
1.2
V
Note 3, VCC e 5.0V
150
82434LX/82434NX
Functional Operating Range (VCC e 5V g 5%; TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
VOL1
Output Low Voltage
VOH1
Output High Voltage
VOL2
Output Low Voltage
VOH2
Output High Voltage
IOL1
Output Low Current
IOH1
Output High Current
IOL2
Output Low Current
IOH2
Output High Current
IOL3
Output Low Current
IOH3
Output High Current
IOL4
Output Low Current
IOH4
Output High Current
Min
Test
Conditions
Max
Unit
0.5
V
Note 4
V
Note 4
V
Note 5
V
Note 5
mA
Note 6
mA
Note 6
mA
Note 7
mA
Note 7
mA
Note 8
mA
Note 8
mA
Note 9
mA
Note 9
VCC b 0.5
0.4
2.4
1
b1
3
b2
6
b2
3
b1
IIH
Input Leakage Current
a 10
IIL
Input Leakage Current
b 10
uA
uA
CIN
Input Capacitance
12
pF
FC e 1 MHz
COUT
Output Capacitance
12
pF
FC e 1 MHz
CI/O
I/O Capacitance
12
pF
FC e 1 MHz
NOTES:
1. VIL1 and VIH1 apply to the following signals: A[31:0], BE[7:0] Ý, D/CÝ, W/RÝ, M/IOÝ, HLOCKÝ, ADSÝ, PCHKÝ,
HITMÝ, CACHEÝ, SMIACTÝ, PCLKIN, HCLKIN, HCLKOSC, FLSHBUFÝ, MEMCSÝ, SERRÝ, PERRÝ, MEMREQÝ,
GNTÝ, PLOCKÝ, STOPÝ, IRDYÝ, TRDYÝ, FRAMEÝ, C/BE[3:0] Ý.
2. VIL2 and VIH2 apply to the following signals: PPOUT[1:0], EOL.
3. VT1b, VT1 a and VH1 apply to PWROK. VT2b, VT2 a and VH2 apply to TESTEN.
4. VOL1 and VOH1 apply to the following signals: HIG[4:0], MIG[2:0], PIG[3:0], DRVPCI, MDLE, PCIRSTÝ.
5. VOL2 and VOH2 apply to the following signals: REQÝ, MEMACKÝ, FRAMEÝ, C/BE[3:0] Ý, TRDYÝ, IRDYÝ, STOPÝ,
PLOCKÝ, DEVSELÝ, PAR, PERRÝ, SERRÝ, BOFFÝ, AHOLD, BRDYÝ, NAÝ, EADSÝ, KENÝ, INV, A[31:0],
PCLKOUT, HCLKA–HCLKF, CALE, COE[1:0] Ý, CWE[7:0] Ý, CADV[1:0] Ý, CADS[1:0] Ý, CAA[6:3], CAB[6:3],
RAS[5:0] Ý, CAS[7:0] Ý, MA[10:0], WEÝ.
6. IOL1 and IOH1 apply to the following signals: HIG[4:0], MIG[2:0], PIG[3:0], DRVPCI, MDLE, PCIRSTÝ.
7. IOL2 and IOH2 apply to the following signals: C/BE[3:0] Ý, REQÝ, MEMACKÝ, MA[10:0], WEÝ.
8. IOL3 and IOH3 apply to the following signals: FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ, DEVSELÝ, PAR, PERRÝ,
SERRÝ.
9. IOL4 and IOH4 apply to the following signals: BOFFÝ, AHOLD, BRDYÝ, NAÝ, EADSÝ, KENÝ, INV, CPURST, INIT,
A[31:0], PCLKOUT, CALE, COE[1:0] Ý, CADS[1:0] Ý, CADV[1:0] Ý, CWE[7:0] Ý, CAA[6:3], CAB[6:3], RAS[5:0] Ý,
CAS[7:0] Ý.
151
82434LX/82434NX
9.4 82434NX DC Characteristics
Functional Operating Range (VCC e 5V g 5%; VCC3 e 3.135 to 3.465 V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Unit
Test
Conditions
VIL1
Input Low Voltage
b 0.3
0.8
V
Note 1, VCC e 4.75V
VIH1
Input High Voltage
2.2
VCC a 0.3
V
Note 1, VCC e 5.25V
VIL2
Input Low Voltage
b 0.3
1.35
V
Note 2, VCC e 4.75V
VIH2
Input High Voltage
3.85
VCC a 0.3
V
Note 2, VCC e 5.25V
VIL3
Input Low Voltage
b 0.3
0.8
V
Note 3, Vccq e 3.135V
VIH3
Input High Voltage
2.2
VCC a 0.3
V
Note 3, Vccq e 3.465V
VT1
Schmitt Trigger Threshold Voltage, Falling Edge
0.7
1.35
V
Note 4, VCC e 5.0V
VT1 a
Schmitt Trigger Threshold Voltage, Rising Edge
1.4
2.2
V
Note 4, VCC e 5.0V
VH1
Hysteresis Voltage
0.3
1.2
V
Note 4, VCC e 5.0V
VT2b
Schmitt Trigger Threshold Voltage, Falling Edge
1.25
2.3
V
Note 4, VCC e 5.0V
VT2 a
Schmitt Trigger Threshold Voltage, Rising Edge
2.3
3.7
V
Note 4, VCC e 5.0V
VH2
Hysterersis Voltage
0.3
1.2
V
Note 4, VCC e 5.0V
VOL1
Output Low Voltage
0.5
V
Note 5
VOH1
Output High Voltage
V
Note 5
VOL2
Output Low Voltage
V
Note 6
VOH2
Output High Voltage
V
Note 6
IOL1
Output Low Current
IOH1
Output High Current
IOL2
Output Low Current
152
VCC b 0.5
0.4
2.4
1
b1
mA Note 7
mA Note 7
3
mA Note 8
82434LX/82434NX
Functional Operating Range (VCC e 5V g 5%; VCC3 e 3.135 to 3.465 V;
TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
Min
Test
Conditions
Max
Unit
mA
Note 8
6
mA
Note 9
mA
Note 9
3
mA
Note 10
mA
Note 10
IOH2
Output High Current
IOL3
Output Low Current
b2
IOH3
Output High Current
IOL4
Output Low Current
IOH4
Output High Current
IIH
Input Leakage Current
a 10
uA
IIL
Input Leakage Current
b 10
uA
CIN
Input Capacitance
12
pF
FC e 1 MHz
COUT
Output Capacitance
12
pF
FC e 1 MHz
CI/O
I/O Capacitance
12
pF
FC e 1 MHz
b2
b1
NOTES:
1. VIL1 and VIH1 apply to the following signals: BE[7:0] Ý, D/CÝ, W/RÝ, M/IOÝ, HLOCKÝ, ADSÝ, PCHKÝ, HITMÝ,
CACHEÝ, SMIACTÝ, PCLKIN, HCLKOSC, FLSHBUFÝ, MEMCSÝ, SERRÝ, PERRÝ, MEMREQÝ, GNTÝ, PLOCKÝ,
STOPÝ, IRDYÝ, TRDYÝ, FRAMEÝ, C/BE[3:0] Ý.
2. VIL2 and VIH2 apply to the following signals: PPOUT[1:0], EOL.
3. VIL3 and VIH3 apply to the following signals: A[31:0], HCLKIN.
4. VT1b, VT1 a and VH1 apply to PWROK. VT2b, VT2 a and VH2 apply to TESTEN.
5. VOL1 and VOH1apply to the following signals: HIG[4:0], MIG[2:0], PIG[3:0], DRVPCI, MDLE, PCIRSTÝ.
6. VOL2 and VOH2 apply to the following signals: REQÝ, MEMACKÝ, FRAMEÝ, C/BE[3:0] Ý, TRDYÝ, IRDYÝ, STOPÝ,
PLOCKÝ, DEVSELÝ, PAR, PERRÝ, SERRÝ, BOFFÝ, AHOLD, BRDYÝ, NAÝ, EADSÝ, KENÝ, INV, A[31:0],
PCLKOUT, HCLKA–HCLKF, CALE, COE[1:0] Ý, CWE[7:0] Ý, CADV[1:0] Ý, CADS[1:0] Ý, CAA[6:3], CAB[6:3],
RAS[7:0] Ý, CAS[7:0] Ý, MA[11:0], WEÝ.
7. IOL1 and IOH1 apply to the following signals: HIG[4:0], MIG[2:0], PIG[3:0], DRVPCI, MDLE, A[31:8], A[2:0], PCIRSTÝ.
8. IOL2 and IOH2 apply to the following signals: C/BE[3:0] Ý, REQÝ, MEMACKÝ, MA[11:0], WEÝ.
9. IOL3 and IOH3 apply to the following signals: FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ, DEVSELÝ, PAR, PERRÝ,
SERRÝ.
10. IOL4 and IOH4 apply to the following signals: BOFFÝ, AHOLD, BRDYÝ, NAÝ, EADSÝ, KENÝ, INV, CPURST, INIT,
A[7:3], PCLKOUT, CALE, COE[1:0] Ý, CADS[1:0] Ý, CADV[1:0] Ý, CWE[7:0] Ý, CAA[6:3], CAB[6:3], RAS[7:0] Ý,
CAS[7:0] Ý.
11. The output buffers for BRDYÝ, NAÝ, AHOLD, EADSÝ, INV, BOFFÝ, KENÝ, PENÝ, CPURST, INIT, CALE, CADS[1:0],
CADV[1:0] Ý, CAA[6:3], CAB[6:3], COE[1:0] Ý, CWE[7:0] Ý, A[31:3] AND HCLK[A:F] are powered with VCC3 and therefore drive 3.3V signal levels.
153
82434LX/82434NX
9.5 82434LX AC Characteristics
The AC characteristics given in this section consist of propagation delays, valid delays, input setup requirements, input hold requirements, output float delays, output enable delays, output-to-output delays, pulse
widths, clock high and low times and clock period specifications. Figure 77 through Figure 85 define these
specifications. Section 9.5 lists the 82434LX AC Characteristics. Output test loads are listed in the right
column.
In Figure 77 through Figure 85, VT e 1.5V for the following signals:
A [31:0] , BE [7:0] Ý, PENÝ, D/CÝ, W/RÝ, M/IOÝ, HLOCKÝ, ADSÝ, PCHKÝ, HITMÝ, EADSÝ, BRDYÝ,
BOFFÝ, AHOLD, NAÝ, KENÝ, INV, CACHEÝ, SMIACTÝ, INIT, CPURST, CALE, CADV [1:0] Ý, COE [1:0] Ý,
CWE [7:0] Ý, CADS [1:0] Ý, CAA [6:3] , CAB [6:3] , WEÝ, RAS [5:0] Ý, CAS [7:0] Ý, MA [10:0] , C/BE [3:0] Ý,
FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ, GNTÝ, DEVSELÝ, MEMREQÝ, PAR, PERRÝ, SERRÝ,
REQÝ, MEMCSÝ, FLSHBUFÝ,MEMACKÝ, PWROK, HCLKIN, HCLKA – HCLKF, PCLKIN, PCLKOUT.
VT e 2.5V for the following signals:
PPOUT [1:0] , EOL, HIG [4:0] , PIG [3:0] , MIG [2:0] , DRVPCI, MDLE, PCIRSTÝ.
9.5.1 HOST CLOCK TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Symbol
t1a
Parameter
6.0
t1b
HCLKOSC Low Time
5.0
t2a
HCLKIN Period
15
t2b
HCLKIN Period Stability
t2c
HCLKIN High Time
4
t2d
HCLKIN Low Time
4
t2e
HCLKIN Rise Time
Max
Figure
Notes
82
82
20
82
ps(1)
g 100
82
82
1.5
83
t2f
HCLKIN Fall Time
1.5
83
t3a
HCLKA–HCLKF Output-to-Output Skew
0.5
85
0 pF
t3b
HCLKA–HCLKF High Time
5.0
85
0 pF
t3c
HCLKA–HCLKF Low Time
5.0
85
0 pF
NOTE:
1. Measured on rising edge of adjacent clocks at 1.5V.
154
Min
HCLKOSC High Time
82434LX/82434NX
9.5.2 CPU INTERFACE TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Parameter
Min
t10a
Symbol
ADSÝ, HITMÝ, W/RÝ, M/IOÝ, D/CÝ,
HLOCKÝ, CACHEÝ, BE [7:0] Ý,
SMIACTÝ Setup Time to HCLKIN
Rising
4.6
Max
79
Fig
Notes
t10b
ADSÝ, HITMÝ, W/RÝ, M/IOÝ, D/CÝ,
HLOCKÝ, CACHEÝ, BE [7:0] Ý,
SMIACTÝ Hold Time from HCLKIN
Rising
0.8
79
t11a
PCHKÝ Setup Time to HCLKIN Rising
4.3
79
t11b
PCHKÝ Hold Time from HCLKIN Rising
1.1
79
t12a
A [18:3] Rising Edge Setup Time to
HCLKIN Rising
4.5
79
Setup to HCLKIN rising when
ADSÝ is sampled active by PCMC.
t12aa
A [18:3] Falling Edge Setup Time to
HCLKIN Rising
3.2
79
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12ab
A [18:3] Rising Edge Setup Time to
HCLKIN Rising
4.7
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12ac
A [18:3] Falling Edge Setup Time to
HCLKIN Rising
4.1
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12b
A [31:0] Hold Time from HCLKIN Rising
0.5
79
Hold from HCLKIN rising two
clocks after ADSÝ is sampled
active by PCMC.
t12c
A [31:0] Setup Time to HCLKIN Rising
6.5
79
Setup to HCLKIN rising when
EADSÝ is sampled active by the
CPU.
t12d
A [31:0] Hold Time from HCLKIN Rising
1.5
79
Hold from HCLKIN rising when
EADSÝ is sampled active by the
CPU.
155
82434LX/82434NX
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C) (Continued)
Parameter
Min
Max
Fig
t12e
Symbol
A [31:0] Output Enable from HCLKIN
Rising
0
13
81
t12f
A [31:0] Valid Delay from HCLKIN
Rising
1.3
13
78
t12g
A[31:0] Float Delay from HCLKIN
Rising
0
13
80
t12h
A [2:0] Propagation Delay from
BE [7:0] Ý
1
16
77
0 pF
t13a
BRDYÝ Rising Edge Valid Delay
from HCLKIN Rising
1.7
7.8
78
0 pF
t13b
BRDYÝ Falling Edge Valid Delay
from HCLKIN Rising
1.7
7.6
78
0 pF
t14
NAÝ Valid Delay from HCLKIN
Rising
1.3
7.8
78
0 pF
t15a
AHOLD Valid Delay from HCLKIN
Rising
1.3
7.1
78
0 pF
t15b
BOFFÝ Valid Delay from HCLKIN
Rising
1.8
7.1
78
t16a
EADSÝ, INV, PENÝ Valid Delay from
HCLKIN Rising
1.3
7.4
78
t16b
CPURST Rising Edge Valid Delay
from HCLKIN Rising
0.9
7.5
78
t16c
CPURST Falling Edge Valid Delay
from HCLKIN Rising
0.9
7.0
78
t16d
KENÝ Valid delay from HCLKIN
Rising
1.3
7.6
78
t17
INIT High Pulse Width
2 HCLKs
84
Soft reset via TRC register or
CPU shutdown special cycle
t18
CPURST High Pulse Width
1 ms
84
Hard reset via TRC register, 0 pF
156
Notes
0 pF
0 pF
82434LX/82434NX
9.5.3 SECOND LEVEL CACHE STANDARD SRAM TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Min
Max
Fig
t20a
Symbol
CAA [6:3] /CAB [6:3] Propagation
Delay from A [6:3]
Parameter
0
8.5
77
0 pF
Notes
t20b
CAA [6:3] /CAB [6:3] Valid Delay from
HCLKIN Rising
0
7.2
78
0 pF
t21a
COE [1:0] Ý Falling Edge Valid Delay
from HCLKIN Rising
0
9
78
0 pF
t21b
COE[1:0] Ý Rising Edge Valid Delay
from HCLKIN Rising
0
5.5
78
0 pF
t22a
CWE [7:0] Ý/CBS [7:0] Ý Falling Edge
Valid Delay from HCLKIN Rising
2
14
78
CPU burst or single write to
second level cache, 0 pF
t22b
CWE [7:0] Ý/CBS [7:0] Ý Rising Edge
Valid Delay from HCLKIN Rising
3
14
78
CPU burst or single write to
second level cache, 0 pF
t22c
CWE [7:0] Ý/CBS [7:0] Ý Valid Delay
from HCLKIN Rising
1.4
7.7
78
Cache line Fill, 0 pF
t22d
CWE [7:0] Ý/CBS [7:0] Ý Low Pulse
Width
1 HCLK
84
0 pF
t22e
CWE [7:0] Ý/CBS [7:0] Ý Driven High
before CALE Driven High
-1
85
Last write to second level cache
during cache line fill, 0 pF
t22f
CAA [4:3] /CAB [4:3] Valid before
CWE [7:0] Ý Falling
1.5
85
CPU burst write to second level
cache, 0 pF
t23
CALE Valid Delay from HCLKIN
Rising
0
7.5
78
0 pF
t24
CR/W [1:0] Ý Valid Delay from
HCLKIN Rising
1.5
7.6
78
0 pF
t25
CBS [1:0] Ý Valid Delay from HCLKIN
Rising; Reads from Cache SRAMs
1.0
12.0
78
0 pF
157
82434LX/82434NX
9.5.4 SECOND LEVEL CACHE BURST SRAM TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0
8.5
77
0 pF
0
7.0
78
0 pF
1.5
7.7
78
0 pF
t30a
CAA [6:3] /CAB [6:3] Propagation Delay from A [6:3]
t30b
CAA [6:3] /CAB [6:3] Valid Delay from HCLKIN Rising
t31
CADS [1:0] Ý Valid Delay from HCLKIN Rising
t32
CADV [1:0] Ý Valid Delay from HCLKIN Rising
1.5
7.1
78
0 pF
t33
CWE [7:0] Ý Valid Delay from HCLKIN Rising
1.0
9.0
78
0 pF
t34a
COE [1:0] Ý Falling Edge Valid Delay from HCLKIN Rising
0
9.0
78
0 pF
t34b
COE [1:0] Ý Rising Edge Valid Delay from HCLKIN Rising
0
5.5
78
0 pF
t35
CALE Valid Delay from HCLKIN Rising
0
7.5
78
0 pF
9.5.5 DRAM INTERFACE TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Symbol
Parameter
Min
Max
Fig
Notes
7.5
78
50 pF
84
RASÝ precharge at
beginning of page miss cycle,
50 pF
78
50 pF
84
CASÝ precharge during burst
cycles, 50 pF
t40a
RAS [5:0] Ý Valid Delay from
HCLKIN Rising
0
t40b
RAS [5:0] Ý Pulse Width High
4 HCLKs b 5
t41a
CAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t41b
CAS [7:0] Ý Pulse Width High
1 HCLKIN b 5
t42
WEÝ Valid Delay from HCLKIN
Rising
0
21
78
50 pF
t43a
MA [10:0] Propagation Delay from
A [23:3]
0
23
77
50 pF
t43b
MA [10:0] Valid Delay from
HCLKIN Rising
0
10.1
78
50 pF
7.5
9.5.6 PCI CLOCK TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Symbol
158
Parameter
Min
Fig
Notes
t50a
PCLKOUT High Time
13
Max
82
20 pF
t50b
PCLKOUT Low Time
13
82
20 pF
t51a
PCLKIN High Time
12
82
t51b
PCLKIN Low Time
12
t51c
PCLKIN Rise Time
3
83
t51d
PCLKIN Fall Time
3
83
82
82434LX/82434NX
9.5.7 PCI INTERFACE TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Min
Max
Fig
t60a
Symbol
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ,
PLOCKÝ, PAR, PERRÝ, SERRÝ, DEVSELÝ Valid
Delay from PCLKIN Rising
Parameter
2
11
78
t60b
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ,
PLOCKÝ, PAR, PERRÝ, SERRÝ, DEVSELÝ Output
Enable Delay from PCLKIN Rising
2
t60c
C/BE[3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ,
PLOCKÝ, PAR, PERRÝ, SERRÝ, DEVSELÝ Float
Delay from PCLKIN Rising
2
t60d
C/BE [3:0] Ý, FRAMEÝ, PLOCKÝ, PAR, PERRÝ,
SERRÝ, Setup Time to PCLKIN Rising
7
79
t60da
TRDYÝ, IRDYÝ Setup Time to PCLKIN Rising
8.1
77
t60db
STOPÝ, DEVSELÝ Setup Time to PCLKIN Rising
8.5
77
t60e
C/BE [3:0] Ý, FRAMEÝ, PLOCKÝ, PAR, PERRÝ,
SERRÝ Hold Time from PCLKIN Rising
0
77
t61a
REQÝ, MEMACKÝ Valid Delay from PCLKIN Rising
2
t61b
REQÝ, MEMACKÝ Output Enable Delay from
PCLKIN Rising
2
t61c
REQÝ, MEMACKÝ Float Delay from PCLKIN Rising
2
t62a
FLSHREQÝ, MEMREQÝ Setup Time to PCLKIN
Rising
12
79
t62b
FLSHREQÝ, MEMREQÝ Hold Time from PCLKIN
Rising
0
79
t63a
GNTÝ Setup Time to PCLKIN Rising
10
79
t63b
GNTÝ Hold Time from PCLKIN Rising
0
79
t64a
MEMCSÝ Setup Time to PCLKIN Rising
7
79
t64b
MEMCSÝ Hold Time from PCLKIN Rising
t65
PCIRSTÝ Low Pulse Width
Notes
Min: 0 pF
Max: 50 pF
81
28
12
80
78
Min: 0 pF
Max: 50 pF
81
28
80
0
79
1 ms
84
Hard Reset via TRC
Register, 0 pF
159
82434LX/82434NX
9.5.8 LBX INTERFACE TIMING, 66 MHz (82434LX)
Functional Operating Range (VCC e 4.9V to 5.25V; TCASE e 0§ C to a 70§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0.8
6.5
78
0 pF
0.9
6.5
78
0 pF
0.7
10.9
78
0 pF
t70
HIG [4:0] Valid Delay from HCLKIN Rising
t71
MIG [2:0] Valid Delay from HCLKIN Rising
t72
PIG [3:0] Valid Delay from PCLKIN Rising
t73
PCIDRV Valid Delay from PCLKIN Rising
1
13.5
78
0 pF
t74a
MDLE Falling Edge Valid Delay from HCLKIN Rising
0.6
5.6
78
0 pF
t74b
MDLE Rising Edge Valid Delay from HCLKIN Rising
0.6
6.8
85
0 pF
t75a
EOL, PPOUT [1:0] Setup Time to PCLKIN Rising
7.7
79
t75b
EOL, PPOUT [1:0] Hold Time from PCLKIN Rising
1.0
79
9.5.9 HOST CLOCK TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
t1a
HCLKOSC High Time
6.0
82
t1b
HCLKOSC Low Time
5.0
82
t2a
HCLKIN Period
t2b
HCLKIN Period Stability
t2c
HCLKIN High Time
4
82
t2d
HCLKIN Low Time
4
82
t2e
HCLKIN Rise Time
1.5
83
t2f
HCLKIN Fall Time
1.5
83
t3a
HCLKA–HCLKF Output-to-Output Skew
0.5
85
0 pF
t3b
HCLKA–HCLKF High Time
5.0
82
0 pF
t3c
HCLKA–HCLKF Low Time
5.0
82
0 pF
NOTE:
1. Measured on rising edge of adjacent clocks at 1.5V.
160
16.66
20
82
ps(1)
g 100
82434LX/82434NX
9.5.10 CPU INTERFACE TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Parameter
Min
t10a
Symbol
ADSÝ, HITMÝ, W/RÝ, M/IOÝ, D/CÝ,
HLOCKÝ, CACHEÝ, BE [7:0] Ý,
SMIACTÝ Setup Time to HCLKIN
Rising
4.6
79
t10b
ADSÝ, HITMÝ, W/RÝ, M/IOÝ, D/CÝ,
HLOCKÝ, CACHEÝ, BE [7:0] Ý,
SMIACTÝ Hold Time from HCLKIN
Rising
1.1
79
t11a
PCHKÝ Setup Time to HCLKIN Rising
4.3
79
t11b
PCHKÝ Hold Time from HCLKIN Rising
1.1
79
t12a
A [18:3] Rising Edge Setup Time to
HCLKIN Rising
4.5
79
Setup to HCLKIN rising when
ADSÝ is sampled active by PCMC.
t12aa
A [18:3] Falling Edge Setup Time to
HCLKIN Rising
3.2
79
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12ab
A [18:3] Rising Edge Setup Time to
HCLKIN Rising
4.7
79
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12ac
A [18:3] Falling Edge Setup Time to
HCLKIN Rising
4.1
79
Setup to HCLKIN Rising when
ADSÝ is Sampled Active by
PCMC.
t12b
A [31:0] Hold Time from HCLKIN Rising
0.5
79
Hold from HCLKIN rising two
clocks after ADSÝ is sampled
active by PCMC.
t12c
A [31:0] Setup Time to HCLKIN Rising
6.5
79
Setup to HCLKIN rising when
EADSÝ is sampled active by the
CPU.
t12d
A [31:0] Hold Time from HCLKIN Rising
1.5
79
Hold from HCLKIN rising when
EADSÝ is sampled active by the
CPU.
t12e
A [31:0] Output Enable from HCLKIN
Rising
t12f
A [31:0] Valid Delay from HCLKIN Rising
t12g
A [31:0] Float Delay from HCLKIN
Rising
0
Max
13
Fig
Notes
81
1.3
13
78
0
13
80
0 pF
161
82434LX/82434NX
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
Min
Max
Fig
1
16
77
0 pF
BRDYÝ Rising Edge Valid Delay
from HCLKIN Rising
2.1
7.9
78
0 pF
t13b
BRDYÝ Falling Edge Valid Delay
from HCLKIN Rising
2.1
7.9
78
0 pF
t14
NAÝ Valid Delay from HCLKIN
Rising
1.4
8.4
78
0 pF
t15a
AHOLD Valid Delay from HCLKIN
Rising
2.0
7.6
78
0 pF
t15b
BOFFÝ Valid Delay from HCLKIN
Rising
2.0
7.6
78
t16a
EADSÝ, INV, PENÝ Valid Delay from
HCLKIN Rising
2.0
8.0
78
t16b
CPURST Rising Edge Valid Delay
from HCLKIN Rising
1.2
7.5
78
t16c
CPURST Falling Edge Valid Delay
from HCLKIN Rising
1.2
7.5
78
t16d
KENÝ Valid delay from HCLKIN
Rising
1.7
8.2
78
t17
INIT High Pulse Width
t18
CPURST High Pulse Width
t12h
A [2:0] Propagation Delay from
BE [7:0] Ý
t13a
162
Notes
0 pF
2 HCLKs
84
Soft reset via TRC register or
CPU shutdown special cycle
1 ms
84
Hard reset via TRC register, 0 pF
82434LX/82434NX
9.5.11 SECOND LEVEL CACHE STANDARD SRAM TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Max
Fig
t20a
Symbol
CAA [6:3] /CAB [6:3]
Propagation Delay from A [6:3]
0
8.5
77
0 pF
Notes
t20b
CAA [6:3] /CAB [6:3] Valid
Delay from HCLKIN Rising
0
7.2
78
0 pF
t21a
COE [1:0] Ý Falling Edge Valid
Delay from HCLKIN Rising
0
9
78
0 pF
t21b
COE[1:0] Ý Rising Edge Valid
Delay from HCLKIN Rising
0
5.5
78
0 pF
t22a
CWE [7:0] Ý/CBS [7:0] Ý
Falling Edge Valid Delay from
HCLKIN Rising
2
14
78
CPU burst or single write to second
level cache, 0 pF
t22b
CWE [7:0] Ý/CBS [7:0] Ý Rising
Edge Valid Delay from HCLKIN
Rising
3
15
78
CPU burst or single write to second
level cache, 0 pF
t22c
CWE [7:0] Ý/CBS [7:0] Ý Valid
Delay from HCLKIN Rising
1.4
7.7
78
Cache line Fill, 0 pF
t22d
CWE [7:0] Ý/CBS [7:0] Ý Low
Pulse Width
1 HCLK
84
0 pF
t22e
CWE [7:0] Ý/CBS [7:0] Ý Driven
High before CALE Driven High
b1
85
Last write to second level cache during
cache line fill, 0 pF
t22f
CAA [4:3] /CAB [4:3] Valid
before CWE [7:0] Ý Falling
1.5
85
CPU burst write to second level cache,
0 pF
t23
CALE Valid Delay from HCLKIN
Rising
0
8
78
0 pF
t24
CR/W [1:0] Ý Valid Delay from
HCLKIN Rising
1.5
8.2
78
0 pF
t25
CBS [1:0] Ý Valid Delay from
HCLKIN Rising; Reads from
Cache SRAMs
1.0
12.0
78
0 pF
163
82434LX/82434NX
9.5.12 SECOND LEVEL CACHE BURST SRAM TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0
8.5
77
0 pF
0
8.2
78
0 pF
1.5
8.2
78
0 pF
t30a
CAA [6:3] /CAB [6:3] Propagation Delay from A [6:3]
t30b
CAA [6:3] /CAB [6:3] Valid Delay from HCLKIN Rising
t31
CADS [1:0] Ý Valid Delay from HCLKIN Rising
t32
CADV [1:0] Ý Valid Delay from HCLKIN Rising
1.5
8.2
78
0 pF
t33
CWE [7:0] Ý Valid Delay from HCLKIN Rising
1.0
10.5
78
0 pF
t34a
COE [1:0] Ý Falling Edge Valid Delay from HCLKIN Rising
0
9.5
78
0 pF
t34b
COE [1:0] Ý Rising Edge Valid Delay from HCLKIN Rising
0
6.0
78
0 pF
t35
CALE Valid Delay from HCLKIN Rising
0
8.5
78
0 pF
9.5.13 DRAM INTERFACE TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
8.0
78
50 pF
84
RASÝ precharge at beginning
of page miss cycle, 50 pF
78
50 pF
84
CASÝ precharge during burst
cycles, 50 pF
t40a
RAS [5:0] Ý Valid Delay from
HCLKIN Rising
0
t40b
RAS [5:0] Ý Pulse Width High
4 HCLKs b 5
t41a
CAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t41b
CAS [7:0] Ý Pulse Width High
1 HCLK b 5
t42
WEÝ Valid Delay from HCLKIN
Rising
0
21
78
50 pF
t43a
MA [10:0] Propagation Delay from
A [23:3]
0
23
77
50 pF
t43b
MA [10:0] Valid Delay from HCLKIN
Rising
0
10.7
78
50 pF
164
8.0
82434LX/82434NX
9.5.14 PCI CLOCK TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Fig
Notes
t50a
Symbol
PCLKOUT High Time
13
Max
82
20 pF
t50b
PCLKOUT Low Time
13
82
20 pF
t51a
PCLKIN High Time
12
82
t51b
PCLKIN Low Time
12
t51c
PCLKIN Rise Time
3
83
t51d
PCLKIN Fall Time
3
83
82
9.5.15 PCI INTERFACE TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
11
78
Min: 0 pF
Max: 50 pF
t60a
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Valid Delay from PCLKIN
Rising
2
t60b
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Output Enable Delay from
PCLKIN Rising
2
t60c
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Float Delay from PCLKIN
Rising
2
t60d
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Setup Time to PCLKIN
Rising
9
79
t60e
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Hold Time from PCLKIN
Rising
0
79
t61a
REQÝ, MEMACKÝ Valid Delay from PCLKIN Rising
2
t61b
REQÝ, MEMACKÝ Output Enable Delay from PCLKIN Rising
2
t61c
REQÝ, MEMACKÝ Float Delay from PCLKIN Rising
2
t62a
FLSHREQÝ, MEMREQÝ Setup Time to PCLKIN Rising
12
81
28
12
80
78
Min: 0 pF
Max: 50 pF
81
28
80
79
165
82434LX/82434NX
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
Min
Max
Fig
t62b
FLSHREQÝ, MEMREQÝ Hold Time
from PCLKIN Rising
0
79
t63a
GNTÝ Setup Time to PCLKIN Rising
10
79
t63b
GNTÝ Hold Time from PCLKIN Rising
0
79
t64a
MEMCSÝ Setup Time to PCLKIN Rising
7
79
t64b
MEMCSÝ Hold Time from PCLKIN Rising
t65
PCIRSTÝ Low Pulse Width
0
79
1 ms
84
Notes
Hard Reset via TRC Register,
0 pF
9.5.16 LBX INTERFACE TIMING, 60 MHz (82434LX)
Functional Operating Range (VCC e 4.75V to 5.25V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
t70
HIG[4:0] Valid Delay from HCLKIN Rising
0.8
6.7
78
0 pF
t71
MIG [2:0] Valid Delay from HCLKIN Rising
0.9
6.5
78
0 pF
t72
PIG [3:0] Valid Delay from PCLKIN Rising
1.5
12
78
0 pF
t73
PCIDRV Valid Delay from PCLKIN Rising
1
13
78
0 pF
t74a
MDLE Falling Edge Valid Delay from HCLKIN Rising
0.6
6.8
78
0 pF
t74b
MDLE Rising Edge Valid Delay from HCLKIN Rising
0.6
6.8
85
0 pF
t75a
EOL, PPOUT [1:0] Setup Time to PCLKIN Rising
7.7
79
t75b
EOL, PPOUT [1:0] Hold Time from PCLKIN Rising
1.0
79
166
82434LX/82434NX
9.6 82434NX AC Characteristics
The AC characteristics given in this section consist of propagation delays, valid delays, input setup requirements, input hold requirements, output float delays, output enable delays, output-to-output delays, pulse
widths, clock high and low times and clock period specifications. Figure 77 through Figure 85 define these
specifications. Output test loads are listed in the right column.
In Figure 77 through Figure 85, VT e 1.5V for the following signals:
A [31:0] , BE [7:0] Ý, PENÝ, D/CÝ, W/RÝ, M/IOÝ, HLOCKÝ, ADSÝ, PCHKÝ, HITMÝ, EADSÝ, BRDYÝ,
BOFFÝ, AHOLD, NAÝ, KENÝ, INV, CACHEÝ, SMIACTÝ, INIT, CPURST, CALE, CADV [1:0] Ý, COE [1:0] Ý,
CWE [7:0] Ý, CADS [1:0] Ý, CAA [6:3] , CAB [6:3] , WEÝ, RAS [5:0] Ý, CAS [7:0] Ý, MA [10:0] , C/BE [3:0] Ý,
FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ, GNTÝ, DEVSELÝ, MEMREQÝ, PAR, PERRÝ, SERRÝ,
REQÝ, MEMCSÝ, FLSHBUFÝ, MEMACKÝ, PWROK, HCLKIN, HCLKA – HCLKF, PCLKIN, PCLKOUT.
VT e 2.5V for the following signals:
PPOUT [1:0] , EOL, HIG [4:0] , PIG [3:0] , MIG [2:0] , DRVPCI, MDLE, PCIRSTÝ
9.6.1 HOST CLOCK TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
t1a
HCLKOSC High Time
6.0
82
t1b
HCLKOSC Low Time
5.0
82
t2a
HCLKIN Period
15
t2b
HCLKIN Period Stability
20
Notes
82
ps(1)
g 100
t2c
HCLKIN High Time
4
82
t2d
HCLKIN Low Time
4
82
t2e
HCLKIN Rise Time
1.5
83
t2f
HCLKIN Fall Time
1.5
83
t3a
HCLKA–HCLKF Output-to-Output Skew
0.5
85
0 pF
t3b
HCLKA–HCLKF High Time
5.0
82
0 pF
t3c
HCLKA–HCLKF Low Time
5.0
82
0 pF
NOTES:
1. Measured on rising edge of adjacent clocks at 1.5V.
167
82434LX/82434NX
9.6.2 CPU INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
t10a
ADSÝ, W/RÝ, Setup Time to HCLKIN
Rising
4.6
79
t10b
BE [7:0] Ý Setup Time to HCLKIN Rising
4.6
79
t10c
HITMÝ Setup Time to HCLKIN Rising
6.4
79
t10d
CACHEÝ, M/IOÝ Setup Time to
HCLKIN Rising
4.6
79
t10e
D/CÝ Setup Time to HCLKIN Rising
4.0
79
t10f
HLOCKÝ, SMIACTÝ, Setup Time to
HCLKIN Rising
4.0
79
t10g
HITMÝ, M/IOÝ, D/CÝ, Hold Time from
HCLKIN Rising
0.7
79
t10h
W/RÝ, HLOCKÝ, Hold Time from
HCLKIN Rising
0.8
79
t10i
ADSÝ, BE [7:0] Ý Hold Time from
HCLKIN Rising
1.1
79
t10j
CACHEÝ, SMIACTÝ Hold Time from
HCLKIN Rising
1.1
79
t11a
PCHKÝ Setup Time to HCLKIN Rising
4.3
79
t11b
PCHKÝ Hold Time from HCLKIN Rising
1.1
79
t12a
A [31:0] Setup Time to HCLKIN Rising
2.7
79
t12b
A [31:0] Hold Time from HCLKIN Rising
0.5
t12c
A [31:0] Setup Time to HCLKIN Rising
6.0
168
Notes
Setup to HCLKIN rising when
ADSÝ is sampled active by PCMC.
HOLD from HCLKIN Rising two
clocks after ADSÝ is sampled
active by PCMC
79
Setup to HCLKIN rising when
EADSÝ is sampled active by the
CPU.
82434LX/82434NX
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V;
TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
t12d
A [31:0] Hold Time from HCLKIN
Rising
t12e
A [31:0] Output Enable from HCLKIN
Rising
t12f
Min
Max
1.5
Fig
79
Notes
Hold from HCLKIN rising when
EADSÝ is sampled active by
the CPU.
0
13
81
A [31:0] Valid Delay from HCLKIN
Rising
1.3
13
78
t12g
A [31:0] Float Delay from HCLKIN
Rising
0
13
80
t12h
A[2:0] Propagation Delay from
BE [7:0] Ý
1.0
16
77
0 pF
t13a
BRDYÝ Rising Edge Valid Delay
from HCLKIN Rising
1.6
7.5
78
0 pF
t13b
BRDYÝ Falling Edge Valid Delay
from HCLKIN Rising
1.6
7.5
78
0 pF
t14
NAÝ Valid Delay from HCLKIN
Rising
.9
7.6
78
0 pF
t15a
AHOLD Valid Delay from HCLKIN
Rising
1.5
7.0
78
0 pF
t15b
BOFFÝ Valid Delay from HCLKIN
Rising
1.5
7.0
78
0 pF
t16a
EADSÝ, INV, PENÝ Valid Delay from
HCLKIN Rising
1.5
7.5
78
0 pF
t16b
CPURST Rising Edge Valid Delay
from HCLKIN Rising
1.2
7.0
78
0 pF
t16c
CPURST Falling Edge Valid Delay
from HCLKIN Rising
1.2
7.0
78
0 pF
t16d
KENÝ Valid delay from HCLKIN
Rising
1.5
7.5
78
0 pF
t17
INIT High Pulse Width
2 HCLKs
84
0 pF
t18
CPURST High Pulse Width
1 ms
84
0 pF; Hard reset via
TRC register
0 pF
169
82434LX/82434NX
9.6.3 SECOND LEVEL CACHE STANDARD SRAM TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Max
Fig
t20a
Symbol
CAA [6:3] /CAB [6:3] Propagation Delay from
A [6:3]
0
8.5
77
0 pF
t20b
CAA [6:3] /CAB [6:3] Valid Delay from
HCLKIN Rising
0
7.2
78
0 pF
t21a
COE [1:0] Ý Falling Edge Valid Delay from
HCLKIN Rising
0
9
78
0 pF
t21b
COE[1:0] Ý Rising Edge Valid Delay from
HCLKIN Rising
0
5.5
78
0 pF
t22a
CWE [7:0] Ý/CBS [7:0] Ý Falling Edge Valid
Delay from HCLKIN Rising
2
14
78
CPU burst or single write to
second level cache, 0 pF
t22b
CWE [7:0] Ý/CBS [7:0] Ý Rising Edge Valid
Delay from HCLKIN Rising
3
14
78
CPU burst or single write to
second level cache, 0 pF
t22c
CWE [7:0] Ý/CBS [7:0] Ý Valid Delay from
HCLKIN Rising
1.0
7.7
78
Cache line Fill, 0 pF
t22d
CWE [7:0] Ý/CBS [7:0] Ý Low Pulse Width
1 HCLK
84
0 pF
t22e
CWE [7:0] Ý/CBS [7:0] Ý Driven High before
CALE Driven High
b1
85
Last write to second level
cache during cache line
fill, 0 pF
t22f
CAA [4:3] /CAB [4:3] Valid before
CWE [7:0] Ý Falling
1.5
85
CPU burst write to second
level cache, 0 pF
t23
CALE Valid Delay from HCLKIN Rising
0
8.0
78
0 pF
t24
CR/W [1:0] Ý Valid Delay from HCLKIN
Rising
1.5
8.2
78
0 pF
t25
CBS [1:0] Ý Valid Delay from HCLKIN
Rising; Reads from Cache SRAMs
1.0
12.0
78
0 pF
t26a
CCS [1:0] Ý Propagation Delay from ADSÝ
Falling
7.0
77
0 pF; First access
after powerdown
t26b
CCS [1:0] Ý Valid Delay from HCLKIN Rising
8.2
78
0 pF; Entering powerdown
170
1.5
Notes
82434LX/82434NX
9.6.4 SECOND LEVEL CACHE BURST SRAM TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0
8.5
77
0 pF
0
8.2
78
0 pF
1.5
8.0
78
0 pF
t30a
CAA [6:3] /CAB [6:3] Propagation Delay from A [6:3]
t30b
CAA [6:3] /CAB [6:3] Valid Delay from HCLKIN Rising
t31
CADS [1:0] Ý Valid Delay from HCLKIN Rising
t32
CADV [1:0] Ý Valid Delay from HCLKIN Rising
1.5
8.0
78
0 pF
t33
CWE [7:0] Ý Valid Delay from HCLKIN Rising
1.5
9.0
78
0 pF
t34a
COE [1:0] Ý Falling Edge Valid Delay from HCLKIN Rising
0.5
9.0
78
0 pF
t34b
COE [1:0] Ý Rising Edge Valid Delay from HCLKIN Rising
0.5
6.0
78
0 pF
t35
CALE Valid Delay from HCLKIN Rising
0
8.0
78
0 pF
9.6.5 DRAM INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
8.0
78
50 pF
84
RASÝ precharge at beginning
of page miss cycle, 50 pF
78
50 pF
84
CASÝ precharge during burst
cycles, 50 pF
t40a
RAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t40b
RAS [7:0] Ý Pulse Width High
4 HCLKs b 5
t41a
CAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t41b
CAS [7:0] Ý Pulse Width High
1 HCLKIN b 5
t42
WEÝ Valid Delay from HCLKIN
Rising
0
21
78
50 pF
t43a
MA [10:0] Propagation Delay from
A [23:3]
0
23
77
50 pF
t43b
MA [10:0] Valid Delay from HCLKIN
Rising
0
10.7
78
50 pF
t43c
MA11 Propagation Delay from
A [25:24]
0
28.0
77
50 pF
t43d
MA11 Valid Delay from HCLKIN
Rising
0
12
78
50 pF
8.0
171
82434LX/82434NX
9.6.6 PCI CLOCK TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Fig
Notes
t50a
Symbol
PCLKOUT High Time
13
Max
82
20 pF
t50b
PCLKOUT Low Time
13
82
20 pF
t51a
PCLKIN High Time
12
82
t51b
PCLKIN Low Time
12
t51c
PCLKIN Rise Time
3
83
t51d
PCLKIN Fall Time
3
83
82
9.6.7 PCI INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
11
78
Min: 0 pF
Max: 50 pF
t60a
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Valid Delay from PCLKIN
Rising
2
t60b
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Output Enable Delay from
PCLKIN Rising
2
t60c
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Float Delay from PCLKIN
Rising
2
t60d
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Setup Time to PCLKIN
Rising
7
79
t60e
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Hold Time from PCLKIN
Rising
0
79
t61a
REQÝ, MEMACKÝ Valid Delay from PCLKIN Rising
2
t61b
REQÝ, MEMACKÝ Output Enable Delay from PCLKIN Rising
2
t61c
REQÝ, MEMACKÝ Float Delay from PCLKIN Rising
2
t62a
FLSHREQÝ, MEMREQÝ Setup Time to PCLKIN Rising
12
79
t62b
FLSHREQÝ, MEMREQÝ Hold Time from PCLKIN Rising
0
79
172
81
28
12
80
78
81
28
80
Min: 0 pF
Max: 50 pF
82434LX/82434NX
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V;
TCASE e 0§ C to a 85§ C) (Continued)
Symbol
Parameter
Min
Max
Fig
t63a
GNTÝ Setup Time to PCLKIN Rising
10
79
t63b
GNTÝ Hold Time from PCLKIN Rising
0
79
t64a
MEMCSÝ Setup Time to PCLKIN Rising
7
79
t64b
MEMCSÝ Hold Time from PCLKIN Rising
0
79
t65
PCIRSTÝ Low Pulse Width
1 ms
84
Notes
Hard Reset via TRC Register,0 pF
9.6.8 LBX INTERFACE TIMING, 66 MHz (82434NX), PRELIMINARY
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0.8
6.5
78
0 pF
MIG [2:0] Valid Delay from HCLKIN Rising
0.9
6.5
78
0 pF
PIG [3:0] Valid Delay from PCLKIN Rising
1.5
12
78
0 pF
t70
HIG[4:0] Valid Delay from HCLKIN Rising
t71
t72
t73
PCIDRV Valid Delay from PCLKIN Rising
1
13
78
0 pF
t74a
MDLE Falling Edge Valid Delay from HCLKIN Rising
0.6
6.0
78
0 pF
t74b
MDLE Rising Edge Valid from HCLKIN Rising
0.6
6.0
85
0 pF
t75a
EOL, PPOUT [1:0] Setup Time to PCLKIN Rising
7.7
79
t75b
EOL, PPOUT [1:0] Hold Time from PCLKIN Rising
1.0
79
9.6.9 HOST CLOCK TIMING, 50 and 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
t1a
HCLKOSC High Time
6.0
82
t1b
HCLKOSC Low Time
5.0
82
t2a
HCLKIN Period
t2b
HCLKIN Period Stability
t2c
HCLKIN High Time
4
82
t2d
HCLKIN Low Time
4
82
t2e
HCLKIN Rise Time
1.5
83
t2f
HCLKIN Fall Time
1.5
83
t3a
HCLKA–HCLKF Output-to-Output Skew
0.5
85
0 pF
t3b
HCLKA–HCLKF High Time
5.0
82
0 pF
t3c
HCLKA–HCLKF Low Time
5.0
82
0 pF
16.66
20
82
ps(1)
g 100
NOTES:
1. Measured on rising edge of adjacent clocks at 1.5V.
173
82434LX/82434NX
9.6.10 CPU INTERFACE TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
t10a
ADSÝ, W/RÝ, Setup Time to HCLKIN
Rising
4.6
79
t10b
BE [7:0] Ý Setup Time to HCLKIN Rising
4.6
79
t10c
HITMÝ Setup Time to HCLKIN Rising
6.8
79
t10d
CACHEÝ, M/IOÝ Setup Time to
HCLKIN Rising
4.6
79
t10e
D/CÝ Setup Time to HCLKIN Rising
4.6
79
t10f
HLOCKÝ, SMIACTÝ, Setup Time to
HCLKIN Rising
4.6
79
t10g
HITMÝ, M/IOÝ, D/CÝ, Hold Time from
HCLKIN Rising
0.7
79
t10h
W/RÝ, HLOCKÝ Hold from HCLKIN
Rising
0.8
79
t10i
ADSÝ, BE [7:0] Ý Hold Time from
HCLKIN Rising
0.9
79
t10j
CACHEÝ, SMIACTÝ Hold Time from
HCLKIN Rising
1.1
79
t11a
PCHKÝ Setup Time to HCLKIN Rising
4.3
79
t11b
PCHKÝ Hold Time from HCLKIN Rising
1.1
79
t12a
A [31:0] Setup Time to HCLKIN Rising
3.0
79
Setup to HCLKIN rising when
ADSÝ is sampled active by PCMC.
t12b
A [31:0] Hold Time from HCLKIN Rising
0.5
79
HOLD from HCLKIN Rising two
clocks after ADSÝ is sampled
active by PCMC
t12c
A [31:0] Setup Time to HCLKIN Rising
6.5
79
Setup to HCLKIN rising when
EADSÝ is sampled active by the
CPU.
t12d
A [31:0] Hold Time from HCLKIN Rising
1.5
79
Hold from HCLKIN rising when
EADSÝ is sampled active by the
CPU.
174
82434LX/82434NX
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
(Continued)
Symbol
Parameter
Min
Max
Fig
Notes
t12e
A [31:0] Output Enable from HCLKIN
Rising
0
13
81
t12f
A [31:0] Valid Delay from HCLKIN
Rising
1.3
13
78
t12g
A [31:0] Float Delay from HCLKIN
Rising
0
13
80
t12h
A[2:0] Propagation Delay from
BE [7:0] Ý
1.0
16
77
0 pF
t13a
BRDYÝ Rising Edge Valid Delay
from HCLKIN Rising
2.1
7.9
78
0 pF
t13b
BRDYÝ Falling Edge Valid Delay
from HCLKIN Rising
2.1
7.9
78
0 pF
t14
NAÝ Valid Delay from HCLKIN
Rising
1.4
8.4
78
0 pF
t15a
AHOLD Valid Delay from HCLKIN
Rising
2.0
7.6
78
0 pF
t15b
BOFFÝ Valid Delay from HCLKIN
Rising
2.0
7.6
78
0 pF
t16a
EADSÝ, INV, PENÝ Valid Delay from
HCLKIN Rising
2.0
8.0
78
0 pF
t16b
CPURST Rising Edge Valid Delay
from HCLKIN Rising
1.2
7.5
78
0 pF
t16c
CPURST Falling Edge Valid Delay
from HCLKIN Rising
1.2
7.5
78
0 pF
t16d
KENÝ Valid delay from HCLKIN
Rising
1.7
8.2
78
0 pF
t17
INIT High Pulse Width
2 HCLKs
84
0 pF
t18
CPURST High Pulse Width
1 ms
84
0 pF; Hard reset via TRC register
0 pF
175
82434LX/82434NX
9.6.11 SECOND LEVEL CACHE STANDARD SRAM TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Max
Fig
t20a
Symbol
CAA [6:3] /CAB [6:3] Propagation Delay
from A [6:3]
0
8.5
77
0 pF
t20b
CAA [6:3] /CAB [6:3] Valid Delay from
HCLKIN Rising
0
7.2
78
0 pF
t21a
COE [1:0] Ý Falling Edge Valid Delay
from HCLKIN Rising
0
9.0
78
0 pF
t21b
COE[1:0] Ý Rising Edge Valid Delay
from HCLKIN Rising
0
5.5
78
0 pF
t22a
CWE [7:0] Ý/CBS [7:0] Ý Falling Edge
Valid Delay from HCLKIN Rising
2
14
78
CPU burst or single write to
second level cache, 0 pF
t22b
CWE [7:0] Ý/CBS [7:0] Ý Rising Edge
Valid Delay from HCLKIN Rising
3
15
78
CPU burst or single write to
second level cache, 0 pF
t22c
CWE [7:0] Ý/CBS [7:0] Ý Valid Delay
from HCLKIN Rising
1.4
7.7
78
Cache line Fill, 0 pF
t22d
CWE [7:0] Ý/CBS [7:0] Ý Low Pulse
Width
14
84
0 pF
t22e
CWE [7:0] Ý/CBS [7:0] Ý Driven High
before CALE Driven High
-1
85
Last write to second level
cache during cache line fill, 0 pF
t22f
CAA [4:3] /CAB [4:3] Valid before
CWE [7:0] Ý Falling
1.5
85
CPU burst write to
second level cache, 0 pF
t23
CALE Valid Delay from HCLKIN Rising
0
8
78
0 pF
t24
CR/W [1:0] Ý Valid Delay from HCLKIN
Rising
1.5
8.2
78
0 pF
t25
CBS [1:0] Ý Valid Delay from HCLKIN
Rising; Reads from Cache SRAMs
1.0
12.0
78
0 pF
t26a
CCS [1:0] Ý Propagation Delay from
ADSÝ Falling
7.0
77
0 pF; First access after
powerdown
t26b
CCS [1:0] Ý Valid Delay from HCLKIN
Rising
8.2
78
0 pF; Entering powerdown
176
1.5
Notes
82434LX/82434NX
9.6.12 SECOND LEVEL CACHE BURST SRAM TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0
8.5
77
0 pF
0
8.2
78
0 pF
1.5
8.2
78
0 pF
t30a
CAA [6:3] /CAB [6:3] Propagation Delay from A [6:3]
t30b
CAA [6:3] /CAB [6:3] Valid Delay from HCLKIN Rising
t31
CADS [1:0] Ý Valid Delay from HCLKIN Rising
t32
CADV [1:0] Ý Valid Delay from HCLKIN Rising
1.5
8.2
78
0 pF
t33
CWE [7:0] Ý Valid Delay from HCLKIN Rising
1.0
10.5
78
0 pF
t34a
COE [1:0] Ý Falling Edge Valid Delay from HCLKIN Rising
0
9.5
78
0 pF
t34b
COE [1:0] Ý Rising Edge Valid Delay from HCLKIN Rising
0
6.0
78
0 pF
t35
CALE Valid Delay from HCLKIN Rising
0
8.5
78
0 pF
9.6.13 DRAM INTERFACE TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
8.0
78
50 pF
84
RASÝ precharge at beginning
of page miss cycle, 50 pF
78
50 pF
84
CASÝ precharge during burst
cycles, 50 pF
t40a
RAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t40b
RAS [7:0] Ý Pulse Width High
4 HCLKs – 5
t41a
CAS [7:0] Ý Valid Delay from
HCLKIN Rising
0
t41b
CAS [7:0] Ý Pulse Width High
1 HCLK – 5
t42
WEÝ Valid Delay from HCLKIN
Rising
0
21
78
50 pF
t43a
MA [10:0] Propagation Delay from
A [23:3]
0
23
77
50 pF
t43b
MA [10:0] Valid Delay from HCLKIN
Rising
0
10.7
78
50 pF
t43c
MA11 Propagation Delay from
A [25:24]
0
24.3
77
50 pF
t43d
MA11 Valid Delay from HCLKIN
Rising
0
12
78
50 pF
8.0
177
82434LX/82434NX
9.6.14 PCI CLOCK TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Parameter
Min
Fig
Notes
t50a
Symbol
PCLKOUT High Time
13
Max
82
20 pF
t50b
PCLKOUT Low Time
13
82
20 pF
t51a
PCLKIN High Time
12
82
t51b
PCLKIN Low Time
12
t51c
PCLKIN Rise Time
3
83
t51d
PCLKIN Fall Time
3
83
82
9.6.15 PCI INTERFACE TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max Fig
t60a
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Valid Delay from PCLKIN
Rising
2
t60b
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Output Enable Delay from
PCLKIN Rising
2
t60c
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Float Delay from PCLKIN
Rising
2
t60d
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Setup Time to PCLKIN
Rising
9
79
t60e
C/BE [3:0] Ý, FRAMEÝ, TRDYÝ, IRDYÝ, STOPÝ, PLOCKÝ,
PAR, PERRÝ, SERRÝ, DEVSELÝ Hold Time from PCLKIN
Rising
0
79
t61a
REQÝ, MEMACKÝ Valid Delay from PCLKIN Rising
2
t61b
REQÝ, MEMACKÝ Output Enable Delay from PCLKIN Rising
2
t61c
REQÝ, MEMACKÝ Float Delay from PCLKIN Rising
2
t62a
FLSHREQÝ, MEMREQÝ Setup Time to PCLKIN Rising
12
79
t62b
FLSHREQÝ, MEMREQÝ Hold Time from PCLKIN Rising
0
79
t63a
GNTÝ Setup Time to PCLKIN Rising
10
79
t63b
GNTÝ Hold Time from PCLKIN Rising
0
79
t64a
MEMCSÝ Setup Time to PCLKIN Rising
7
79
t64b
MEMCSÝ Hold Time from PCLKIN Rising
0
79
t65
PCIRSTÝ Low Pulse Width
1 ms
84
178
11
78
Notes
Min: 0 pF
Max: 50 pF
81
28
80
12
78
28
80
Min: 0 pF
Max: 50 pF
81
Hard Reset via
TRC Register,
0 pF
82434LX/82434NX
9.6.16 LBX INTERFACE TIMING, 50 AND 60 MHz (82434NX)
Functional Operating Range (VCC e 4.75V to 5.25V; VCC3 e 3.135V to 3.465V; TCASE e 0§ C to a 85§ C)
Symbol
Parameter
Min
Max
Fig
Notes
0.8
6.7
78
0 pF
t71
MIG [2:0] Valid Delay from HCLKIN Rising
0.9
6.5
78
0 pF
t72
PIG [3:0] Valid Delay from PCLKIN Rising
1.5
12
78
0 pF
t73
PCIDRV Valid Delay from PCLKIN Rising
1
13
78
0 pF
t74a
MDLE Falling Edge Valid Delay from HCLKIN Rising
0.6
6.8
78
0 pF
t74b
MDLE Rising Edge Valid Delay from HCLKIN Rising
0.6
6.8
85
0 pF
t75a
EOL, PPOUT [1:0] Setup Time to PCLKIN Rising
7.7
79
t75b
EOL, PPOUT [1:0] Hold Time from PCLKIN Rising
1.0
79
t70
HIG [4:0] Valid Delay from HCLKIN Rising
9.6.17 TIMING DIAGRAMS
290479 – 87
Figure 77. Propagation Delay
290479 – 88
Figure 78. Valid Delay from Rising Clock Edge
290479 – 89
Figure 79. Setup and Hold Times
179
82434LX/82434NX
290479 – 90
Figure 80. Float Delay
290479 – 91
Figure 81. Output Enable Delay
290479 – 92
Figure 82. Clock High and Low Times and Period
290479 – 93
Figure 83. Clock Rise and Fall Times
180
82434LX/82434NX
290479 – 94
Figure 84. Pulse Width
290479 – 95
Figure 85. Output-to-Output Delay
181
82434LX/82434NX
10.0 PINOUT AND PACKAGE INFORMATION
10.1 Pin Assignment
Except for the pins listed in Figure 86 notes, the pin assignment for the 82434LX and 82434NX are the same.
290479 – 96
NOTES:
1. For the 82434NX, pin 105 e RAS6Ý, 106 e RAS7Ý, and 109 e MA11. These pins are no connects for the 82434LX
and are signal connections for the 82434NX.
2. For the 82434NX, pins 23, 35, 43, 74, 86, and 102 are 3.3V VDD pins (i.e., VDD3). These pins are VDD pins for the
82434LX.
Figure 86. PCMC Pin Assignment
182
82434LX/82434NX
Table 21. 82434LX Alphabetical Pin Assignment
Pin Name
Pin Ý
Type
Pin Name
Pin Ý Type
A0
204
t/s
AHOLD
33
out
A1
205
t/s
BE0Ý
56
in
Pin Name
Pin Ý
Type
CAS5Ý
138
out
CAS6Ý
134
out
A2
206
t/s
BE1Ý
53
in
CAS7Ý
132
out
A3
12
t/s
BE2Ý
57
in
CBE0Ý
146
t/s
A4
9
t/s
BE3Ý
59
in
CBE1Ý
145
t/s
A5
10
t/s
BE4Ý
55
in
CBE2Ý
144
t/s
A6
11
t/s
BE5Ý
54
in
CBE3Ý
143
t/s
87
out
A7
14
t/s
BE6Ý
58
in
COE0Ý
A8
13
t/s
BE7Ý
60
in
COE1Ý
85
out
A9
16
t/s
BOFFÝ
30
out
CPURST
25
out
A10
15
t/s
BRDYÝ
32
out
CWE0Ý/CBS0Ý
100
out
A11
18
t/s
CAA3
82
out
CWE1Ý/CBS1Ý
99
out
A12
17
t/s
CAA4
80
out
CWE2Ý/CBS2Ý
98
out
A13
19
t/s
CAA5
78
out
CWE3Ý/CBS3Ý
97
out
A14
21
t/s
CAA6
76
out
CWE4Ý/CBS4Ý
96
out
A15
22
t/s
CAB3
84
out
CWE5Ý/CBS5Ý
95
out
A16
201
t/s
CAB4
81
out
CWE6Ý/CBS6Ý
91
out
A17
202
t/s
CAB5
79
out
CWE7Ý/CBS7Ý
90
out
A18
203
t/s
CAB6
77
out
D/CÝ
68
in
DEVSELÝ
A19
6
t/s
CACHEÝ
64
in
170
s/t/s
A20
7
t/s
CADS0Ý,CR/W0Ý
93
out
DRVPCI
186
out
A21
200
t/s
CADS1Ý,CR/W1Ý
94
out
EADSÝ
34
out
A22
4
t/s
out
EOL
161
in
196
t/s
CADV0Ý (82434LX)
CADV0Ý/CCS0Ý
(82434NX)
88
A23
FLSHREQÝ
162
in
FRAMEÝ
173
s/t/s
GNTÝ
163
in
HCLKA
42
out
A24
3
t/s
A25
8
t/s
A26
5
A27
A28
89
t/s
CADV1Ý (82434LX)
CADV1Ý/CCS1Ý
(82434NX)
out
197
t/s
CALE
101
out
HCLKB
41
out
2
t/s
CAS0Ý
135
out
HCLKC
40
out
137
out
A29
198
t/s
CAS1Ý
HCLKD
39
out
A30
207
t/s
CAS2Ý
133
out
HCLKE
38
out
A31
199
t/s
CAS3Ý
131
out
HCLKF
37
out
in
CAS4Ý
136
out
HCLKIN
50
in
ADSÝ
66
183
82434LX/82434NX
Table 21. 82434LX Alphabetical Pin Assignment (Continued)
Pin Name
Pin Ý
Type
HCLKOSC
52
in
HIG0
184
out
HIG1
183
out
HIG2
182
out
HIG3
181
out
HIG4
180
out
HITMÝ
65
in
HLOCKÝ
71
in
INIT
26
out
INV
28
out
IRDYÝ
142
s/t/s
KENÝ
29
out
M/IOÝ
61
in
MA0
122
out
MA1
121
out
MA2
119
out
MA3
118
out
MA4
117
out
MA5
116
out
MA6
114
out
MA7
113
out
MA8
112
out
MA9
111
out
MA10
184
110
out
Pin Name
MA11
(82434NX only)
Pin Ý Type
109
out
MDLE
185
out
MEMACKÝ
195
out
MEMCSÝ
164
in
MEMREQÝ
165
in
MIG0
179
out
MIG1
178
out
MIG2
175
out
NAÝ
31
out
NC
70
NC
NC (82434LX only)
105
NC
NC (82434LX only)
106
NC
NC (82434LX only)
109
NC
PAR
171
t/s
PCHKÝ
72
in
PCIRSTÝ
147
out
PCLKIN
156
in
PCLKOUT
174
out
PENÝ
27
out
PERRÝ
169
s/o/d
PIG0
193
out
PIG1
192
out
PIG2
191
out
PIG3
187
out
Pin Name
Pin Ý
Type
PLLAGND
45
V
PLLARC1
46
in
PLLARC2
48
in
PLLAVDD
49
V
PLLAVSS
47
V
PLLBGND
151
V
PLLBRC1
152
in
PLLBRC2
154
in
PLLBVDD
155
V
PLLBVSS
153
V
PLOCKÝ
168
s/t/s
PPOUT0
159
in
PPOUT1
160
in
PWROK
62
in
RAS0Ý
127
out
RAS1Ý
125
out
RAS2Ý
126
out
RAS3Ý
124
out
RAS4Ý
128
out
RAS5Ý
123
out
RAS6Ý
(82434NX only)
105
out
RAS7Ý
(82434NX only)
106
out
82434LX/82434NX
Table 21. 82434LX Alphabetical Pin Assignment (Continued)
Pin Name
Pin Ý
Type
Pin Name
Pin Ý
Type
Pin Name
Pin Ý
Type
REQÝ
194
out
VDD
103
V
VSS
92
V
SERRÝ
172
s/o/d
VDD
120
V
VSS
104
V
SMIACTÝ
69
in
VDD
130
V
VSS
107
V
STOPÝ
167
s/t/s
VDD
139
V
VSS
115
V
TESTEN
63
in
VDD
149
V
VSS
129
V
TRDYÝ
141
s/t/s
VDD
158
V
VSS
140
V
VDD
20
V
VDD
176
V
VSS
148
V
VDD (82434LX)
VDD3 (82434NX)
23
V
VDD
188
V
VSS
150
V
VDD
208
V
VSS
157
V
VDD (82434LX)
VDD3 (82434NX)
35
V
VSS
1
V
VSS
166
V
VDD (82434LX)
VDD3 (82434NX)
43
V
VSS
24
V
VSS
177
V
VSS
36
V
VSS
189
V
VDD
73
V
VSS
44
V
VSS
190
V
VSS
51
V
W/RÝ
67
in
VSS
75
V
WEÝ
108
out
VSS
83
V
VDD (82434LX)
VDD3 (82434NX)
74
V
VDD (82434LX)
VDD3 (82434NX)
86
V
VDD (82434LX)
VDD3 (82434NX)
102
V
185
82434LX/82434NX
Table 22. Numerical Pin Assignment
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
1
VSS
V
32
BRDYÝ
out
62
PWROK
in
2
A28
t/s
33
AHOLD
out
63
TESTEN
in
in
3
A24
t/s
34
EADSÝ
out
64
CACHEÝ
4
A22
t/s
35
V
65
HITMÝ
in
5
A26
t/s
VDD (82434LX)
VDD3 (82434NX)
66
ADSÝ
in
36
VSS
V
67
W/RÝ
in
37
HCLKF
out
68
D/CÝ
in
38
HCLKE
out
69
SMIACTÝ
39
HCLKD
out
70
NC
40
HCLKC
out
71
HLOCKÝ
in
41
HCLKB
out
72
PCHKÝ
in
42
HCLKA
out
73
VDD
V
43
VDD (82434LX)
VDD3 (82434NX)
V
74
VDD (82434LX)
VDD3 (82434NX)
V
44
VSS
V
75
VSS
V
45
PLLAGND
V
76
CAA6
out
46
PLLARC1
in
77
CAB6
out
47
PLLAVSS
V
78
CAA5
out
48
PLLARC2
in
79
CAB5
out
49
PLLAVDD
V
80
CAA4
out
50
HCLKIN
in
81
CAB4
out
51
VSS
V
82
CAA3
out
52
HCLKOSC
in
83
VSS
53
BE1Ý
in
84
CAB3
out
54
BE5Ý
in
85
COE1Ý
out
55
BE4Ý
in
86
56
BE0Ý
in
VDD (82434LX)
VDD3 (82434NX)
57
BE2Ý
in
87
COE0Ý
out
58
BE6Ý
in
88
out
59
BE3Ý
in
CADV0Ý (82434LX)
CADV0Ý/CCS0Ý
(82434NX)
60
BE7Ý
in
89
in
CADV1Ý (82434LX)
CADV1Ý/CCS1Ý
(82434NX)
out
61
M/IOÝ
6
A19
t/s
7
A20
t/s
8
A25
t/s
9
A4
t/s
10
A5
t/s
11
A6
t/s
12
A3
t/s
13
A8
t/s
14
A7
t/s
15
A10
t/s
16
A9
t/s
17
A12
t/s
18
A11
t/s
19
A13
t/s
20
VDD
V
21
A14
t/s
22
A15
23
VDD (82434LX)
VDD3 (82434NX)
V
VSS
V
24
t/s
25
CPURST
out
26
INIT
out
27
PENÝ
out
28
INV
out
29
KENÝ
out
30
31
186
BOFFÝ
NAÝ
out
out
in
NC
V
V
82434LX/82434NX
Table 22. Numerical Pin Assignment (Continued)
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
90
CWE7Ý/CBS7Ý
out
119
MA2
out
151
PLLBGND
V
91
CWE6Ý/CBS6Ý
out
120
VDD
V
152
PLLBRC1
in
92
VSS
V
121
MA1
out
153
PLLBVSS
V
93
CADS0Ý,CR/W0Ý
out
122
MA0
out
154
PLLBRC2
in
94
CADS1Ý,CR/W1Ý
out
123
RAS5Ý
out
155
PLLBVDD
V
95
CWE5Ý/CBS5Ý
out
124
RAS3Ý
out
156
PCLKIN
in
96
CWE4Ý/CBS4Ý
out
125
RAS1Ý
out
157
VSS
V
97
CWE3Ý/CBS3Ý
out
126
RAS2Ý
out
158
VDD
V
98
CWE2Ý/CBS2Ý
out
127
RAS0Ý
out
159
PPOUT0
in
99
CWE1Ý/CBS1Ý
out
128
RAS4Ý
out
160
PPOUT1
in
100
CWE0Ý/CBS0Ý
out
129
VSS
V
161
EOL
in
101
CALE
out
130
VDD
V
162
FLSHREQÝ
in
102
VDD (82434LX)
VDD3 (82434NX)
V
131
CAS3Ý
out
163
GNTÝ
in
132
CAS7Ý
out
164
MEMCSÝ
in
103
VDD
V
133
CAS2Ý
out
165
MEMREQÝ
in
104
VSS
V
134
CAS6Ý
out
166
VSS
105
NC (82434LX)
RAS6Ý (82434NX)
NC
out
135
CAS0Ý
out
167
STOPÝ
106
NC (82434LX)
RAS7Ý (82434NX)
NC
out
136
CAS4Ý
out
168
PLOCKÝ
s/t/s
137
CAS1Ý
out
169
PERRÝ
s/o/d
V
138
CAS5Ý
out
170
DEVSELÝ
s/t/s
out
139
VDD
V
171
PAR
VSS
V
172
SERRÝ
s/o/d
107
VSS
108
WEÝ
V
s/t/s
t/s
109
NC (82434LX)
MA11 (82434NX)
NC
out
140
141
TRDYÝ
s/t/s
173
FRAMEÝ
s/t/s
110
MA10
out
142
IRDYÝ
s/t/s
174
PCLKOUT
out
111
MA9
out
143
CBE3Ý
t/s
175
MIG2
out
112
MA8
out
144
CBE2Ý
t/s
176
VDD
V
113
MA7
out
145
CBE1Ý
t/s
177
VSS
V
114
MA6
out
146
CBE0Ý
t/s
178
MIG1
out
115
VSS
V
147
PCIRSTÝ
out
179
MIG0
out
116
MA5
out
148
VSS
V
180
HIG4
out
117
MA4
out
149
VDD
V
181
HIG3
out
118
MA3
out
150
VSS
V
182
HIG2
out
187
82434LX/82434NX
Table 22. Numerical Pin Assignment (Continued)
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
PinÝ
Pin Name
Type
183
HIG1
out
192
PIG1
out
201
A16
t/s
184
HIG0
out
193
PIG0
out
202
A17
t/s
185
MDLE
out
194
REQÝ
out
203
A18
t/s
186
DRVPCI
out
195
MEMACKÝ
out
204
A0
t/s
187
PIG3
out
196
A23
t/s
205
A1
t/s
188
VDD
V
197
A27
t/s
206
A2
t/s
189
VSS
V
198
A29
t/s
207
A30
t/s
190
VSS
V
199
A31
t/s
208
VDD
V
191
PIG2
out
200
A21
t/s
188
82434LX/82434NX
10.2 Package Characteristics
290479 – 97
Figure 87. 208-Pin Quad Flatpack (QFP) Dimensions
Table 23. 82434LX Package Dimensions
Symbol
Description
Value (mm)
Table 24. 82434NX Package Dimensions
Symbol
Description
Value (mm)
A
Seating Height
3.5 (max)
A
Seating Height
3.7 (max)
A1
Stand-Off Height
0.20–0.50
A1
Stand-Off Height
0.05 – 0.50
A2
Package Height
3.0 (nominal)
A2
Package Height
3.45 (max)
B
Lead Width
0.18 a 0.1/ b 0.05
B
Lead Width
0.13 – 0.27
D
Package Length and
Width, Including Pins
30.6 g 0.3
D
Package Length and
Width, Including Pins
30.6 g 0.3
D1
Package Length and 28 g 0.1
Width, Excluding Pins
D1
Package Length and
Width, Excluding Pins
28 g 0.1
e
Linear Lead Pitch
0.5 g 0.1
e
Linear Lead Pitch
0.5 (nominal)
G
Lead Coplanarity
0.1 (max)
G
Lead Coplanarity
0.1 (max)
L
Lead Length
0.5 g 0.2
L
Lead Length
0.5 g 0.2
i
Lead Angle
0§ –10§
i
Lead Angle
0§ –10§
189
82434LX/82434NX
11.0 TESTABILITY
A NAND tree is provided in the 82434LX and
82434NX PCMCs for Automated Test Equipment
(ATE) board level testing. The NAND tree allows the
tester to test the connectivity of a subset of the
PCMC signal pins.
For the 82434LX, the output of the NAND tree is
driven on pin 109. The NAND tree is enabled when
A24 e 1, A25 e 0, A26 e 1, and TESTEN e 1 at the
rising edge of PWROK. PLL Bypass mode is enabled when A24 e 1, and TESTEN e 1 at the rising
edge of PWROK. In PLL Bypass mode, the 82434LX
and 82434NX PCMC AC specifications are affected
as follows:
1. Output valid delays increase by 20 ns.
2. All hold times are 20 ns.
3. Setup times and propagation delays are
unaffected.
4. Input clock high and low times are 100 ns.
In both the NAND tree test mode and PLL Bypass
mode, TESTEN must remain asserted throughout
the testing. A [28:24] should be set up at least
1 HCLK before the rising edge of PWROK and held
at least 3 HCLKs after PWROK. Table 11 shows the
order of the NAND tree inside the PCMC.
When not in NAND Tree test mode, the 82434LX
drives the output of the host clock PLL onto pin 109.
82434NX Test Modes
The state of A [28:24] , TESTEN, CPURST, and
PWROK can place the 82434NX PCMC into two test
modes. When PWROK is low, A [27:24] and
TESTEN directly control the mode of operation of
190
the PCMC. When PWROK is high, the state of
A [27:24] and TESTEN are latched and the PCMC
remains in the indicated mode until PWROK is again
negated. The high order LBX samples the state of
A27 on the falling edge of CPURST.
When PWROK is low and both TESTEN and A27
are low, the 82434NX drives MA11 onto pin 109. If
both TESTEN and A27 are low when PWROK transitions from low to high, the PCMC continues to
drive MA11 onto pin 109. If the high order LBX samples A27 low on the falling edge of CPURST, it will
tri-state pin 123.
When PWROK is low, TESTEN is low, and A27 is
high the PCMC drives the output of the host clock
PLL onto pin 109. Observing pin 109 when in this
mode indicates if the host clock PLL has locked
onto the correct frequency. If TESTEN is low and
A27 is high when PWROK transitions from low to
high the PCMC continues to drive the output of the
host clock PLL onto pin 109, regardless of the values of TESTEN and A27. If the high order LBX samples A27 high on the falling edge of CPURST, it
drives the output of its host clock PLL onto pin 123.
No phase delay information can be inferred from
these outputs.
When PWROK is low, TESTEN is high, A26 is high,
A25 is low, A28 is high and A24 is high, the PCMC
will drive the output of the NAND tree onto pin 109. If
TESTEN is high, A26 is high, and A25 is low when
PWROK transitions from low to high, the PCMC continues to drive the output of the NAND tree onto
pin 109.
A27 must be pulled low via a pulldown resistor to
ground for normal operation.
82434LX/82434NX
Table 25. NAND Tree Order
Order
Pin Ý
Order
Pin Ý
Order
Pin Ý
1
141
TRDYÝ
Signal
25
199
A31
Signal
49
17
A12
Signal
2
142
IRDYÝ
26
200
A21
50
18
A11
3
143
CBE3Ý
27
201
A16
51
19
A13
4
144
CBE2Ý
28
202
A17
52
21
A14
5
145
CBE1Ý
29
203
A18
53
22
A15
6
146
CBE0Ý
30
204
A0
54
53
BE1Ý
7
159
PPOUT0
31
205
A1
55
54
BE5Ý
8
160
PPOUT1
32
206
A2
56
55
BE4Ý
9
161
EOL
33
207
A30
57
56
BE0Ý
10
162
FLSHBUFÝ
34
2
A28
58
57
BE2Ý
11
163
GNTÝ
35
3
A24
59
58
BE6Ý
12
164
MEMCSÝ
36
4
A22
60
59
BE3Ý
13
165
MEMREQÝ
37
5
A26
61
60
BE7Ý
14
167
STOPÝ
38
6
A19
62
61
M/IOÝ
15
168
PLOCKÝ
39
7
A20
63
64
CACHEÝ
16
169
PERRÝ
40
8
A25
64
65
HITMÝ
17
170
DEVSELÝ
41
9
A4
65
66
ADSÝ
18
171
PAR
42
10
A5
66
67
W/RÝ
19
172
SERRÝ
43
11
A6
67
68
D/CÝ
20
173
FRAMEÝ
44
12
A3
68
69
SMIACTÝ
21
194
REQÝ
45
13
A8
69
71
HLOCKÝ
22
196
A23
46
14
A7
70
72
PCHKÝ
23
197
A27
47
15
A10
71
63
TESTEN
24
198
A29
48
16
A9
ADDITIONAL TESTING NOTES:
1. HCLKOUT[6:1] can be toggled via HCLKIN.
2. CAx[6:3] are flow through outputs via A[6:3] after PWROK transitions high.
3. MA[10:0] are flow through outputs via A[13:3] after PWROK transitions high.
4. CAS[7:0] Ý outputs can be tested by performing a DRAM read cycle.
5. PCLKOUT can be tested in PLL bypass mode, frequency is HCLK/2.
6. PCIRST is the NAND Tree output of Tree Cell 6.
7. INIT is the NAND Tree output of Tree Cell 53.
191