deveopmen
Bus Settings
Preliminary Specifications REV.D
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M16C/80 (100-pin version) group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
29
The default after a reset is the separate bus configuration, and the full CS space multiplex bus configu-
ration cannot be selected in microprocessor mode. If you select “Full CS space multiplex bus”, the 16
bits from A0 to A15 are output for the address
External data bus width control register
b7
b6
b5
b4
b3 b2
b1
Symbol
DS
Address
000B
16
When reset
XXXXX000
2
Bit name
Function
Bit symbol
b0
DS3
DS1
DS0
External area 0 data bus
width bit
External area 1 data bus
width bit
External area 2 data bus
width bit
External area 3 data bus
width bit (Note)
DS2
0 : 8 bits data bus width
1 : 16 bits data bus width
0 : 8 bits data bus width
1 : 16 bits data bus width
0 : 8 bits data bus width
1 : 16 bits data bus width
0 : 8 bits data bus width
1 : 16 bits data bus width
Note: The value after a reset is determined by the input via the BYTE pin.
W
R
A
A
A
A
Nothing is assigned.
When write, set "0". When read, their contents are indeterminate.
Figure 1.7.1. External data bus width control register
Note 1: DRAMC area when using DRAMC.
Note 2:Set the external area mode (modes 0, 1, 2, and 3) using bits 0 and 1 of the processor mode register
1 (address 0005
16
).
External area mode
(Note 2)
Mode 0
Mode 1
Mode 2
Mode 3
E
a
E
a
E
a
E
a
Memory expansion mode
Memory expansion mode
,
Microprocessor mode
Microprocessor mode
Memory expansion mode
,
Microprocessor mode
008000
16
to
1FFFFF
16
200000
16
to
3FFFFF
16
400000
16
to
BFFFFF
16
(Note 1)
C00000
16
to
EFFFFF
16
C00000
16
to
FFFFFF
16
<CS1 area>
008000
16
to
1FFFFF
16
<CS2 area>
200000
16
to
3FFFFF
16
<DRAMC area>
400000
16
to
BFFFFF
16
<CS0 area>
C00000
16
to
EFFFFF
16
<CS0 area>
E00000
16
to
FFFFFF
16
<CS1 area>
008000
16
to
1FFFFF
16
<DRAMC area>
400000
16
to
BFFFFF
16
<CS0 area>
C00000
16
to
EFFFFF
16
<CS0 area>
C00000
16
to
FFFFFF
16
<CS1 area>
100000
16
to
1FFFFF
16
<CS2 area>
200000
16
to
2FFFFF
16
<CS3 area>
C00000
16
to
CFFFFF
16
<CS0 area>
E00000
16
to
EFFFFF
16
<CS0 area>
F00000
16
to
FFFFFF
16
Memory expansion mode
,
Microprocessor mode
No area is
selected.
Table 1.7.2. External area 0 to 3 and external area mode