UPD780957 Datasheet, PDF (53/326 Pages) NEC – 8-Bit Single-Chip Microcontrollers

CHAPTER 3 CPU ARCHITECTURE
3.1.4 Data memory addressing
Addressing is used to specify the address of the instruction to be executed next or the address of a register or
memory to be manipulated when an instruction is executed.
The address of the instruction to be executed next is specified by the program counter (PC) (for details, refer to 3.3
Addressing Instruction Address).
To specify the address in the memory to be manipulated when an instruction is executed, the µPD780958
Subseries is provided with many addressing modes to improve operability. In the area that incorporates data memory
especially (FB00H to FFFFH), specific addressing modes that correspond to the particular functions of an area, such
as the special-function registers (SFR) or general-purpose registers, are available. Figures 3-3 and 3-4 show the data
memory addressing modes. For details of each kind of addressing, refer to 3.4 Addressing of Operand Address.
Figure 3-3. Data Memory Addressing (µPD780957(A))
FFFFH
Special-function registers (SFR)
256 × 8 bits
FF20H
FE1FH
FE00H
FEFFH
FEE0H
FEDFH
General-purpose registers
32 × 8 bits
Internal high-speed RAM
1,024 × 8 bits
FE20H
FE1FH
FB00H
FAFFH
FA1EH
FA1DH
FA00H
F9FFH
F800H
F7FFH
F400H
F3FFH
Reserved
LCD display RAM
30 × 3 bits
Reserved
Internal expansion RAM
1,024 × 8 bits
Reserved
C000H
BFFFH
SFR addressing
Register addressing
Short direct addressing
Direct addressing
Register indirect addressing
Based addressing
Based indexed addressing
Internal ROM
49,152 × 8 bits
0000H
User’s Manual U13655EJ2V1UD
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