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CHAPTER 17
µ
PD178F054
User’s Manual U15104EJ2V0UD
17.2 Internal Expansion RAM Size Switching Register (IXS)
The internal expansion RAM capacity of the
µ
PD178F054 can be changed using the internal expansion RAM size
switching register (IXS). By using this register, the memory of the
µ
PD178F054 can be mapped in the same manner
as a mask ROM version with a different internal expansion RAM capacity.
IXS is set with an 8-bit memory manipulation instruction.
Reset input sets this register to 0CH.
Caution
Do not set a value other than the initial value.
Figure 17-2. Format of Internal Expansion RAM Size Switching Register (IXS)
IXRAM4 IXRAM3 IXRAM2 IXRAM1 IXRAM0
Selection of internal expansion RAM capacity
0
1
1
0
0
0 bytes
Other than above
Setting prohibited
Table 17-3 shows the setting of IXS to perform the same memory mapping as that of a mask ROM version.
Table 17-3. Set Value of Internal Expansion RAM Size Switching Register
Targeted Model
Set Value of IXS
µ
PD178053, 178054
0CH
7
0
6
0
5
0
4
IXRAM4
3
IXRAM3
2
IXRAM2
1
IXRAM1
0
IXRAM0
Symbol
IXS
After reset
0CH
R/W
R/W
Address
FFF4H
Содержание mPD178053
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