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3 MEMORY MAP
3 MEMORY MAP
This chapter explains the memory configuration of the S1C88655.
3.1 MCU Single Chip Mode
The S1C88655 should be placed in single chip mode
when it is used as a single chip microcomputer
without an externally expanded memory. Since this
mode uses the internal ROM, the system can be
operated only in MCU mode. The MPU mode does
not allow the IC to be placed in single chip mode.
This mode does not need an external bus, so the
terminals normally set for the external bus can be
used as general-purpose output ports or I/O ports.
See Chapter 6, "System Controller and Bus
Control", for how to set single chip mode.
4FFFFFH
400000H
3FFFFFH
300000H
2FFFFFH
200000H
1FFFFFH
100000H
0FFFFFH
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
MCU single chip mode
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3.2 MCU Expansion Mode
The S1C88655 must be placed in expansion mode
when it is used with an externally expanded
memory up to 1M bytes × 4.
The internal ROM is enabled in the MCU mode, so
external memory can be assigned to the area from
100000H to 4FFFFFH. See Chapter 6, "System
Controller and Bus Control", for how to set
expansion mode.
3.3 MPU Expansion Mode
The internal ROM area is released in the MPU
mode, so external memory can be assigned to the
area from 000000H to 3FFFFFH. However, the area
from 00C000H to 00FFFFH is assigned to the
internal memory and cannot be used to access an
external device.
External memory
CE0 area
External memory
CE3 area
External memory
CE2 area
External memory
CE1 area
Unused
Internal
font data ROM
(512KB)
I/O memory
Unused
Display data RAM 1
(1KB)
64KB
Unused
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Display data RAM 0
(1KB)
Internal RAM
(8KB)
Internal ROM
(48KB)
MCU expansion mode
Fig. 3.1.1 Memory map
EPSON
1MB
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1MB
External memory
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CE3 area
1MB
External memory
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CE2 area
1MB
External memory
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CE1 area
External memory
CE0 area
I/O memory
Unused
1MB
Display data RAM 1
space
(1KB)
Unused
Display data RAM 0
(1KB)
Internal RAM
(8KB)
External memory
CE0 area
MPU expansion mode
S1C88655 TECHNICAL MANUAL
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