Internal Expansion Ram Size Switching Register (Ixs) - NEC mPD780852 Series Preliminary User's Manual

22.2 Internal Expansion RAM Size Switching Register (IXS)

The internal expansion RAM size switching register (IXS) is used to select the capacity of the internal expansion
RAM.
IXS is set with an 8-bit memory manipulation instruction.
RESET input sets IXS to 0CH.
Figure 22-2. Internal Expansion RAM Size Switching Register (IXS) Format
Address: FFF4H After Reset: 0CH R/W
Symbol 7
IXS 0
IXRAM4
0
Other than above
Caution The initial value of IXS is 0CH. Always set 0BH in this register.
CHAPTER 22 µ PD78F0852
6 5 4
0 0 IXRAM4
IXRAM3 IXRAM2 IXRAM1
1 0 1
Preliminary User's Manual U14581EJ3V0UM00
3 2 1
IXRAM3 IXRAM2 IXRAM1
IXRAM0 Internal Expansion RAM
Capacity Selection
1 512 bytes
Setting prohibited
0
IXRAM0
277