CHAPTER 3 CPU ARCHITECTURE
55
User’s Manual U11302EJ4V0UM
3.1.4 Data memory addressing
The method to specify the address of the instruction to be executed next or the address of a register or memory
area to be manipulated when an instruction is executed is called addressing.
The address of the instruction to be executed next is specified by the program counter (PC) (for details, refer
to
3.3 Instruction Address Addressing
).
To address the memory area to be manipulated when an instruction is executed, the
µ
PD780208 Subseries has
many addressing modes to improve the operability. Especially, in the areas to which the data memory is assigned
(addresses FB00H to FFFFH), the special-function registers (SFRs) and general-purpose registers can be
addressed in accordance with thier function.
Data memory addressing is shown in Figures 3-6 to 3-10. For details of each addressing, refer to
3.4 Operand
Address Addressing
.
Figure 3-6. Data Memory Addressing (
µ
PD780204 and
µ
PD780204A)
0000H
Internal ROM
32768 x 8 bits
Internal high-speed RAM
1024 x 8 bits
Buffer RAM
64 x 8 bits
Reserved
8000H
7FFFH
FFFFH
General-purpose registers
32 x 8 bits
Special-function registers (SFRs)
256 x 8 bits
FAC0H
FABFH
FB00H
FAFFH
FEE0H
FEDFH
FF00H
FEFFH
VFD display RAM
80 x 8 bits
FA80H
FA7FH
FA30H
FA2FH
Reserved
FF20H
FF1FH
Direct addressing
Register indirect addressing
Based addressing
Based indexed addressing
FE20H
FE1FH
SFR addressing
Register addressing
Short direct
addressing