Service manual

I
5. Memory mapping
5·1 . Memory map as seen from the Z-80 (SC7852)
OOOOH
PC-'600
ROM
(CSOO,)
4000H
,
PC -1S00
PC·'SOO
Slot 2
ROM
52
,
ROM
(e)
(CS24)
(CSOOi)
,
,
8000 H
Slot 1 Slot 1 Slot 2 Slot 2
S1 51 52 52
(A) (8) (e) (0)
oooo H
PC-1S00
(RAM3)
FFFFH
Bank 0 Bank 1 Bank 2 Bank 3
Th e memory space directly accessible by the Z·80 is 64KB,
however, the memory space is expanded to 320KB for the
PC · 1OO0 by means of bank selection. Bank selection is done
according to the contents of the Z·80 I/ F address 31 H.
When the Z·80 accesses a space in OOOH""3FFFH , bank
o or bank 1
is selected depending on the status in bit
o (bO) of the I/O address 31 H.
If bO = 0, bank 0 -+ PVaUT: 0
If bO = 1, bank 1 -+ PVOUT: 1
PVaUT (SC7852 output) is used to represent the chosen
bank (0 or 1). PVaUT is 0 when bank 0 is selected. It is
1 when bank 1 is selected.
Similarly, when the Z·80 accesses a space in 4000H '""
7FF FH , bank 0 '"" bank 7 is selected depending on the
status in the bits, b3 - b1. pvaUT, PU, and PT are used
to represent bank 0 thru bank 7.
The PVOUT, PU, and PT conform to the I/O address 31H
and the space accessed by the Z-80.
It is possible to sense the status of the 1/0 address 31 H.
CE·'SOOP
CE·l600P
ROM ROM
(Printer) (Fl oppy
disk)
Ca$Sel1e
(CS24)
Bank 4
Bank
5
Table-2
Bank Z- 80 a ce_in g
No. lilac,
o OQOOH-3FFFH
, ,
o 40(X)H -1FfF H
, ,
2
3
c
,
t
,
-
PC - l600
PC·1600
ROM
(CS123)
BankS Bank 7
St'tu l in 1he 1 /0
add reu 31H
PT PU PV
U
o
· ·· · 00'·00'
.·· . 0'0·010
•• •• 011.0'1
7
, ···· 11 1·1 11
o
8000H- BFFFH • 0 0 0 • • • • 0 0 0
1
.001 •••• 001
2
3
c
. ' 00 .· •• 100
,
t
.101 •••• 101
,
7
t
·111 •••• 1 10
o COOOH - FFFFH
o • • • • • • • • • 0
, t
, • • • • • • • • ° 1
0: DON'T CARE
- 7 -