Theory of Operation
I/O ADDRESSING
An I/O address is chosen for the ZT 8825 to distinguish it from any
other I/O board that exists on the STD bus. If more than one ZT 8825
is used in a system, each must have a unique address.
In addition, the two least significant bits (LSBs) of the I/O address
define the location of the Map Registers and Configuration Register
used on the ZT 8825 during implementation of EMS. See page 3-14
for more information about EMS and the ZT 8825 Software Support
Package manual for EMS programming considerations.
Table 3-3
Default I/O Address Assignments.
Address
Default
Default
Default
Line
Condition
Base Address
(HEX)
A15
W14 out
1
A14
W13 out
1
A13
W12 out
1
E
A12
W11 in
0
A11
1 hardwired
1
A10
1 hardwired
1
A9
1 hardwired
1
E
A8
0 hardwired
0
A7
W10 in
0
A6
W9 out
1
A5
W8 out
1
6
A4
W7 in
0
A3
1 hardwired
1
A2
-
0
A1
-
0
8
A0
-
0
3-10
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