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CHAPTER 3 CPU ARCHITECTURE
User’s Manual U12978EJ3V0UD
38
3.1.4 Data memory addressing
The
µ
PD789800 Subseries provides a variety of addressing modes which take account of memory manipulability,
etc. Especially at addresses corresponding to data memory area (FE00H to FFFFH), particular addressing modes
are possible to meet the functions of the special function registers (SFR) and general-purpose registers. Figures 3-3
and 3-4 show the data memory addressing modes.
Figure 3-3. Data Memory Addressing (
µ
µµ
µ
PD789800)
Special function registers (SFR)
256 × 8 bits
Internal high-speed RAM
256 × 8 bits
Internal ROM
8,192 × 8 bits
FFFFH
0000H
Direct addressing
Register indirect
addressing
Based addressing
FF00H
FEFFH
FF20H
FF1FH
FE20H
FE1FH
SFR addressing
Short direct
addressing
Reserved
FE00H
FDFFH
2000H
1FFFH