UPD75238GJ NEC [NEC], UPD75238GJ Datasheet - Page 128

• Manufacturer Part Number: UPD75238GJ
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC [NEC]

128
(9) Display data memory
Display data memory stores segment data for display. It is mapped to addresses 1A0H to 1FFH in data
memory. The display controller automatically reads display data (DMA operation). Area not used for
display can be used as normal data memory.
Display data is manipulated with data memory manipulation instructions in 1-, 4-, and 8-bit units. With
8-bit manipulation instructions, only even-numbered addresses can be specified.
Display data memory locations at 1FCH to 1FFH, 1BEH, and 1BFH are also used as key scan registers KS0,
KS1, and KS2.
Caution Special care must be paid when a program developed for the PD75238 is transported to the
16 display segments, and do not contain data memory at the addresses (1A0H + 4n, 1A1H +
4n).
PD75216A or the PD75217. This is because the PD75216A and the PD75217 allow up to
Table 4-9 Data Memory Locations Also Used as Key Scan Registers
Key scan register
KS0
KS1
KS2
Data memory locations
1FCH, 1FDH
1BEH, 1BFH
1FEH, 1FFH
PD75238