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CPU
Zilog
APPENDIX A
16 KILOBYTE EPROM MEMORY
CPU
The CPU onboard memory (09-0288) has been
incr~ased
in capa-
city
by
the
substitute of four 2732 EPROMS for the previ-
ously used 2716 EPROMS.
This
change
increases
the
EPROM
capacity
from 8 kilobytes to 16 kilobytes of resident EPROM
for local read-only memory.
The EPROM addressing is from
0
through
3FFF Hex.
The 2 kilobytes of RAM read/write memory
remains
the
same
using
four
2114
RAMS.
However,
the
addressing
of the RAM memory is from locations 4000 through
47FF Hex.
The main memory address begins at location 8000
Hex.
When
the
local memory space is enabled, a dead space exists from
locations 4800 through 7FFF
Hex.
As
long
as
the
board
memory
enable
bit
DO
of
the SCR is reset (logic 1), the
total local memory space 0 through 47FF Hex will overlay the
segment
0
main memory space.
On power-up or system reset,
the SCR DO bit is cleared to logic 0 and enables
the
local
memory.
Writing
a
logic
1 to bit DO of the SCR disables
onboard memory and maps all
memory
reference
to
offbaard
memory.
A-I
Zilog
A-I
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