Memory and I/O Capability
MEMORY MAPS
Figures 5-1 through 5-6 represent some of the possible memory maps
for the ZT 8809A, along with jumper configuration drawings. Figures
5-1 and 5-2 show the factory default configuration for an STD DOS
system. In this example, one socket is used for a 256 Kbyte EPROM
drive. Another socket is used for a 128 Kbyte EPROM drive, and the
RAM sockets hold a total of 256 Kbytes to be used for system RAM.
Note that the 32 Kbyte RAM drive and timekeeper are shadowed
behind the lower 128K address space of the 256K ROM drive.
FFFFFh
DFFFFh
D8000h
5FFFFh
40000h
3FFFFh
0h
256 Kbyte ROM Drive
w/ 256 Kbyte EPROM
128 Kbyte ROM Drive
w/ 128 Kbyte EPROM
On-Board RAM
w/ 128 Kbyte RAMs
Note: Shaded portion represents off-board memory address space.
C0000h
32 Kbyte RAM Drive
and Timekeeper
Figure 5–1. STD DOS Factory Default Memory Map.
5-4