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5.4.6 Special function register (SFR) addressing
[Function]
The memory-mapped special function register (SFR) is addressed with 8-bit immediate data in an instruction word.
This addressing is applied to the 240-byte spaces FF00H to FFCFH and FFE0H to FFFFH. However, the SFR
mapped at FF00H to FF1FH can also be accessed with short direct addressing.
[Operand format]
[Description example]
MOV PM0, A; when selecting PM0 (FF20H) as sfr
[Illustration]
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Effective address
CHAPTER 5 CPU ARCHITECTURE
Identifier
sfr
Special function register name
sfrp
16-bit manipulatable special function register name (even address only)
Instruction code 1
7
OP code
sfr-offset
15
1
1
1
1
1
1
Description
1
1
1
0
1
1
0
0
0
1
0
0
0
0
0
0
8
7
1
1
OP code
20H (sfr-offset)
0
SFR
125
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