CHAPTER 3 CPU ARCHITECTURE
3.1.4 Data memory addressing
The µPD789426, 789436, 789446, and 789456 Subseries are provided with a variety of addressing modes to
make memory manipulation as efficient as possible. At the addresses corresponding to data memory area (FD00H
to FFFFH) especially, specific addressing modes that correspond to the particular function an area, such as the
special function registers are available. Figures 3-7 through 3-12 show the data memory addressing modes.
Figure 3-7. Data Memory Addressing (µPD789425, 789435)
FFFFH
Special function registers (SFRs)
SFR addressing
256 × 8 bits
FF20H
FF1FH
FF00H
FEFFH
Short direct
Internal high-speed RAM
addressing
512 × 8 bits
FE20H
FE1FH
Direct adressing
FD00H
Register indirect
addressing
FCFFH
Reserved
FA05H
FA04H
Based addressing
LCD display RAM
5 × 4 bits
FA00H
F9FFH
Reserved
3000H
2FFFH
Internal ROM
12288 × 8 bits
0000H
User’s Manual U15075EJ1V0UM00
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NEC [ NEC ]
