Table 5-14 Floppy Disk Control Port Address Offsets 1 ADDRESS (HEX) FUNCTION ----------------------------------------- 1 280H MAIN STATUS REG 1 282H COMMAND/DATA REG Table 5-15 Floppy Disk Controller Port Address Offsets 1 ADDRESS (HEX) FUNCl'ION ---------------------------------- 1 2E0H DACK PORT Z-80A I/O CONTROLLER This section describes the function of the Z-80A I/O controller and how it communicates with the 80186 processor. Functional Description The Z-80A microprocessor performs I/O processing for the five RS232 channels (four user ports and a serial printer port).
The I/O processing circuitry includes three Z-80A SIO (serial input/ output) devices, two 8253 counters, 4K of RAM and a control ROM for the processor. The 4K of RAM is used for temporary storage and buffering. See Tables 5-16, 5-17 and 5-18. Table 5-16 Z-SIA Port Assignaents Z-80 ADDRESS 1 ASSIGNMENT 1 ----------------1--------------------------------------------1 00H - 03H 1 SI00 1 04H - 07H 1 SIOI 1 08H - 0BH 1 SI02 1 0CH 1 RDPERR 1 10H - 13H 1 TMRI 1 14H - 17H 1 TMR2 1 18H 1 CONTROL LATCH 1 lCH 1 ADR LATCH 1 - ______ 1 1 5-25