Data Memory Addressing - NEC mPD178054 Series User 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, refer to
3.3 Instruction Address Addressing).
Several addressing modes are provided for addressing the memory relevant to the execution of instructions for
the µ PD178054 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 (SFR) 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, refer to 3.4 Operand Address Addressing.
F F F F H
Special function
registers (SFRs)
256 × 8 bits
F F 2 0 H
F F 1 F H
F F 0 0 H
F E F F H
General-purpose registers
32 × 8 bits
F E E 0 H
F E D F H
Internal high-speed RAM
1024 × 8 bits
F E 2 0 H
F E 1 F H
F B 0 0 H
F A F F H
6 0 0 0 H
5 F F F H
Internal ROM
24576 × 8 bits
0 0 0 0 H
44
CHAPTER 3 CPU ARCHITECTURE
Figure 3-4. Data Memory Addressing of µ PD178053
SFR addressing
Register addressing
Reserved
User's Manual U15104EJ2V0UD
Short direct
addressing
Direct addressing
Register indirect
addressing
Based addressing
Based indexed
addressing