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3.4.5 Special function register (SFR) addressing
[Function]
A 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 SFRs
mapped at FF00H to FF1FH can be accessed with short direct addressing.
[Operand format]
Identifier
sfr
sfrp
[Description example]
MOV PM0, A; when selecting PM0 (FF20H) as sfr
Operation code
[Illustration]
7
15
Effective address
1
1
CHAPTER 3 CPU ARCHITECTURE
Special function register name
16-bit manipulatable special function register name (even address
only)
1
1
1
1
0
0
1
0
0
OP code
sfr-offset
8 7
1
1
1
1
1
1
User's Manual U16899EJ2V0UD
Description
0
1
1
0
OP code
0
0
0
0
20H (sfr-offset)
0
SFR
77
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