P R E L I M I N A R Y Am186ER MICROCONTROLLER BLOCK DIAGRAM INT2/INTA0 INT3/INTA1/IRQ CLKOUTA INT1/SELECT INT4 TMROUT0 INT0 CLKOUTB TMRIN0 NMI X2 X1 VCC Clock and Power Management Unit Interrupt Control Unit Execution Unit GND Control Registers TMRIN1 Timer Control Unit 0 1 (WDT) Max Count B Registers Max Count A Registers 16-Bit Count Registers Control Registers DRQ0 DRQ1 DMA Unit 2 0 1 20-Bit Source Pointers 20-Bit Destination Pointers 16-Bit Count Registers Control Registers Control Registers Control Registers TMROUT1 RES Control Registers ARDY SRDY Refresh Control Unit PSRAM Control Unit Control Registers 32 Kbyte RAM (16K x 16) Bus Interface Unit PIO31– PIO0* Control Registers Asynchronous Serial Port S2 S1/IMDIS S0/SREN DT/R DEN HOLD HLDA S6/ CLKSEL1 UZI/ CLKSEL2 PIO Unit Chip-Select Unit TXD RXD Control Registers Synchronous Serial Interface RD WHB A19–A0 WLB AD15–AD0 SCLK PCS6/A2 LCS/ONCE0 BHE/ADEN SDEN0 SDEN1 PCS5/A1 MCS3/RFSH MCS2–MCS0 WR SDATA PCS3–PCS0 UCS/ONCE1 ALE Note: * All PIO signals are shared with other physical pins. See the pin descriptions beginning on page 26 and Table 2 on page 31 for information on shared functions. 2 Am186TMER and Am188TMER Microcontrollers