UPD78F0138 NEC, UPD78F0138 Datasheet - Page 438

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

27.2 Internal Expansion RAM Size Switching Register
438
This register is used to set the internal expansion RAM capacity via software.
This register is set by an 8-bit memory manipulation instruction.
RESET input sets IXS to 0CH.
Cautions 1. Be sure to set the value of the relevant mask ROM version at initialization.
The IXS settings required to obtain the same memory map as mask ROM versions are shown in Table 27-3.
Cautions 1. When using a mask ROM version, be sure to set the value indicated in Table 27-3 to IXS.
Address: FFF4H
Symbol
IXS
2. The
2. The
Figure 27-2. Format of Internal Expansion RAM Size Switching Register (IXS)
IXRAM4
Table 27-3. Internal Expansion RAM Size Switching Register Settings
µ
µ
7
0
0
0
After reset: 0CH
PD78F0134 does not support the
PD78F0134 does not support the
IXRAM3
6
0
1
1
µ
µ
µ
µ
µ
µ
Target Mask ROM Versions
PD780131
PD780132
PD780133
PD780134
PD780136
PD780138
Other than above
R/W
CHAPTER 27
IXRAM2
User’s Manual U16228EJ2V0UD
5
0
1
0
IXRAM4
IXRAM1
µ
PD78F0134, 78F0138
4
0
1
µ
µ
PD780136 and 780138.
PD780136 and 780138.
IXRAM3
IXRAM0
IXS Setting
3
0CH
0CH
0CH
0CH
0AH
0AH
0
0
Internal expansion RAM capacity selection
0 bytes
1024 bytes
Setting prohibited
IXRAM2
2
IXRAM1
1
IXRAM0
0