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6 SYSTEM CONTROLLER AND BUS CONTROL
6.2 Bus Mode and CPU Mode
6.2.1 Bus mode
In order to set bus specifications to match the
configuration of external expanded memory, two
different bus modes described below are selectable
using the bus mode setting register BUSMOD.
(1) Single chip mode (BUSMOD = "0")
(2) Expansion mode (BUSMOD = "1")
Single chip mode
The single chip mode setting applies when the
S1C88655 is used as a single chip microcom-
puter without external expanded memory.
Since this mode uses the internal ROM, the
system can only be operated in the MCU mode.
In the MPU mode, the system cannot be set to
the single chip mode.
Since there is no need for an external bus line in
this mode, terminals normally set for bus use
can be used as general-purpose output ports or
I/O ports.
Address space
08FFFFH
Internal
font data ROM
(512KB)
010000H
00FFFFH
I/O memory
00FF00H
00FEFFH
Unused
00EC00H
00EBFFH
Display data RAM 1
(1KB)
00E800H
00E7FFH
Unused
00E400H
00E3FFH
Display data RAM 0
(1KB)
00E000H
00DFFFH
Internal RAM
(8KB)
00C000H
00BFFFH
Internal ROM
(48KB)
000000H
Fig. 6.2.1.1 Memory map for single chip mode
Expansion mode
The expansion mode setting applies when the
S1C88655 is used with up to 1M bytes × 4 of
external expanded memory.
Because internal ROM is being used in the MCU
mode, external devices can be assigned to the
area from 100000H to 4FFFFFH.
Since the internal ROM area is released in the
MPU mode, external devices can be assigned to
the area from 000000H to 3FFFFFH. However,
the area from 00C000H to 00FFFFH is assigned
to internal memory and cannot be used to
access an external device.
36
Pin configuration
Pin name
Function
R00
R00
|
|
R07
R07
R10
R10
|
|
R17
R17
R20
R20
|
|
64KB
R23
R23
space
R24
R24
R25
R25
R30
R30
R31
R31
R32
R32
R33
R33
P00
P00
|
|
P07
P07
P24
P24
P25
P25
Address space
4FFFFFH
External memory
CE0 area
400000H
3FFFFFH
External memory
CE3 area
300000H
2FFFFFH
External memory
CE2 area
200000H
1FFFFFH
External memory
CE1 area
100000H
0FFFFFH
Unused
090000H
08FFFFH
Internal
font data ROM
(512KB)
010000H
00FFFFH
I/O memory
00FF00H
00FEFFH
Unused
00EC00H
00EBFFH
Display data RAM 1
(1KB)
00E800H
00E7FFH
Unused
00E400H
00E3FFH
Display data RAM 0
(1KB)
00E000H
00DFFFH
Internal RAM
(8KB)
00C000H
00BFFFH
Internal ROM
(48KB)
000000H
Fig. 6.2.1.2 Memory map for MCU expansion mode
Address space
3FFFFFH
External memory
CE3 area
300000H
2FFFFFH
External memory
CE2 area
200000H
1FFFFFH
External memory
CE1 area
100000H
0FFFFFH
External memory
CE0 area
010000H
00FFFFH
I/O memory
00FF00H
00FEFFH
Unused
00EC00H
00EBFFH
Display data RAM 1
(1KB)
00E800H
00E7FFH
Unused
00E400H
00E3FFH
Display data RAM 0
(1KB)
00E000H
00DFFFH
Internal RAM
(8KB)
00C000H
00BFFFH
External memory
CE0 area
000000H
Fig. 6.2.1.3 Memory map for MPU expansion mode
EPSON
Pin configuration
Pin name
Function
1MB
R00
A0
space
|
|
R07
A7
R10
A8
1MB
|
|
space
R17
A15
R20
A16
|
|
1MB
R23
A19
space
R24
RD
R25
WR
R30
R30/CE0
1MB
R31
R31/CE1
space
R32
R32/CE2
R33
R33/CE3
P00
D0
|
|
P07
D7
P24
P24/BREQ
P25
P25/BACK
1MB
space
Pin configuration
Pin name
Function
1MB
R00
A0
space
|
|
R07
A7
R10
A8
1MB
|
|
space
R17
A15
R20
A16
|
|
1MB
R23
A19
space
R24
RD
R25
WR
R30
CE0
R31
R31/CE1
R32
R32/CE2
R33
R33/CE3
P00
D0
|
|
P07
D7
P24
P24/BREQ
P25
P25/BACK
1MB
space
S1C88655 TECHNICAL MANUAL
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