Memory and I/O Capability
I/O Expansion (IOEXP) provides an additional address line for STD
bus I/O boards, and may be jumpered to Vcc or ground via jumper
W61. It is not dynamically driven by the ZT 8809A. Factory default
ties IOEXP to ground.
FFFFh
0400h
03FFh
03F8h
03F7h
0380h
037Fh
02FFh
02F8h
0040h
0000h
Serial Port 1 (COM 1)
Printer Port 1 (LPT 1)
8259A Interrupt
Controller
Note: Shaded portion represents off-board I/O address space.
Serial Port 2 (COM 2)
8254 Timers
0378h
0377h
0300h
02F7h
0048h
0047h
003Fh
0028h
0027h
0020h
001Fh
Figure 5–8. ZT 8809A I/O Map.
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