UPD78F0988AGC-8BS Renesas Electronics America, UPD78F0988AGC-8BS Datasheet - Page 309

• Manufacturer Part Number: UPD78F0988AGC-8BS
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0988AGC-8BS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

18.2 Internal Expansion RAM Size Switching Register
expansion RAM size switching register (IXS). By setting IXS, the same memory map as mask ROM versions with
different internal expansion RAM capacities is possible.
Symbol
For the PD78F0988A, it is possible to select the capacity of the internal expansion RAM using the internal
IXS is set by an 8-bit memory manipulation instruction.
RESET input sets this register to 0CH.
The values set to IXS in order to obtain the same memory map as mask ROM versions are shown in Table 18-3.
Caution When mask ROM versions are used, IXS should be set to the values shown in Table 18-3. The
IXS
7
0
setting value for the PD780982, 780983, and 780984 is 0CH, so it is not necessary to change
the initial value.
Table 18-3. Set Values of Internal Expansion RAM Size Switching Register
Figure 18-2. Format of Internal Expansion RAM Size Switching Register
6
0
5
0
IXRAM4 IXRAM3 IXRAM2 IXRAM1 IXRAM0
4
Applicable Mask ROM Versions
PD780982
PD780983
PD780984
PD780986
PD780988
3
CHAPTER 18
2
User’s Manual U13029EJ7V1UD
1
0
PD78F0988A
IXRAM4 IXRAM3
Other than above
0
0
Set Value of IXS
Address
FFF4H
1
1
0CH
0AH
IXRAM2 IXRAM1 IXRAM0
0
1
After reset
0CH
1
0
0
0
R/W
R/W
Internal expansion RAM
capacity selection
1024 bytes
No internal
expansion RAM
Setting prohibited
307