Memory Mapping - Sharp PC-1600 Service Manual

5. Memory mapping

5-1. Memory map as seen from the Z· 8 0 (SC7852)
OOOOH
PC· 1 600
ROM
(CSOO1)
4000H
PC· 1 600
ROM
(CS001 )
8000H
Siot 1
S1
(A)
COOOH
PC· 1 600
(RAM3)
FFFFH -_.-
Bank 0
The memory space directly accessible by the Z· 8 0 is 64KB,
however, the memory space is expanded to 320KB for the
PC· 1 600 by means of bank selection. Bank selection is done
according to the contents of the Z· 8 0 I/F address 31 H.
When the Z· 8 0 accesses aspace
o
or bank 1 is selected depending
o
(bO) of the 1/0 address 31 H.
If bO 0, bank 0 PVOUT: 0
=
-+
If bO 1, bank 1 PVOUT: 1
=
-+
PVOUT (SC7852 output)
bank (0 or 1). PVOUT is 0 when bank 0 is selected. It is
1 when bank 1 is selected.
Similarly, when the Z· 8 0
7FFFH, bank 0 ~ bank 7 is selected depending on the
status in the bits, b3 ~ bl. PVOUT, PU, and PT are used
to represent bank 0 thru bank 7.
The PVOUT, PU, and PT conform to the 1/0 address 31 H
and the space accessed the Z· 8 0.
by
It is possible to sense the status of the 1/0 address 31 H,
Siot 2
S2
(C)
Siot 1
Siot 2
Sl S2
(B) (C)
Bank 1
Bank 2
in 000H~3FFFH, bank
on the status in bit
is used to represent the chosen
accesses aspace in 4000H ~
I
CE· 1 600P CE-1600P
PC· 1 600
ROM
ROM
ROM
(Printer) (Floppy
I
(CS24)
disk)
I
Cassette
I
Siot 2
S2
(0)
(CS24)
Bank 3 Bank4 Bank 5
Table· 2
z· a o
Bank accessing
space
No.
0 OOOOH-3FFFH
t
1
4000H-7FFFH
0
t
1
2 t
3
t
t
C
t
5
t
6
t
7
0
8000H-BFFFH
t
1
t
2
t
3
C t
5 t
t
6
7 t
COOOH-FFFFH
0
t
1
-
P C-1600
PC· 1 600
ROM
(CS123)
Bank 6 Bank 7
Status in the 1/0
PT PU
address31H
· · · · · · · · . .
b7 b6 b5 b4 b3 b2 bl bC
.
· · · · ·
* * *
1
* * * * 0 0 0 * 0 0
· · ·
·
0
0 0 1 0
*
· · · · ·
0
0 1 0 1
· ·
0 1 1 0 1
*
* *
· · · · ·
0 0 0
1 1
· · · · ·
0 0
1 1 1
·
· · · ·
0
1 1 1 1
· · · · ·
1
1 1 1 1
· · · · ·
0 0 0 0
0
· · · · ·
0 0 0 0
1
· · · · ·
0 0 0
1 1
·
·
0 0
1 1 1
* * *
· ·
0 0 1 0
1
* * *
0 0
1 1 1
* * * * *
0
1 1 1 1
*
* * * *
· ·
1 1 1
1 1
.
* * *
· · ·
0
* * * * *
·
1
* * * * * * * *
': DON'T CARE
PV
OUT
0
1
0
1
I
0
1
0
1
0
1
0
1
0
1
0
1
0
0
0
1