Data Memory Addressing - NEC mPD780852 Series Preliminary User's Manual

3.1.4 Data memory addressing

Addressing refers to the method of specifying the address of the instruction to be executed next or the address
of the register or memory relevant to the execution of instructions. The address of an instruction to be executed next
is addressed by the program counter (PC) (for details, see 3.3 Instruction Address Addressing).
Several addressing modes are provided for addressing the memory relevant to the execution of instructions for
the µ PD780852 Subseries, based on operability and other considerations. For areas containing data memory in
particular, special addressing methods designed for the functions of special function registers (SFRs) and general-
purpose registers are available for use. Data memory addressing is illustrated in Figures 3-4 to 3-6. For the details
of each addressing mode, see 3.4 Operand Address Addressing.
FFFFH
Special function
registers (SFRs)
256 × 8 bits
FF20H
FF1FH
FF00H
FEFFH
General registers
32 × 8 bits
FEE0H
FEDFH
Internal high-speed RAM
1,024 × 8 bits
FE20H
FE1FH
FB00H
FAFFH
Reserved
FA6DH
FA6CH
LCD display RAM
20 × 4 bits
FA59H
FA58H
Reserved
F800H
F7FFH
Internal expansion RAM
512 × 8 bits
F600H
F5FFH
Reserved
8000H
7FFFH
Internal ROM
32,768 × 8 bits
0000H
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CHAPTER 3 CPU ARCHITECTURE
Figure 3-4. Data Memory Addressing ( µ PD780851(A))
SFR addressing
Register addressing
Preliminary User's Manual U14581EJ3V0UM00
Short direct
addressing
Direct addressing
Register indirect
addressing
Based addressing
Based indexed
addressing