5 special-function register (sfr) addressing – NEC uPD78056Y User Manual

Page 125

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125

CHAPTER 5 CPU ARCHITECTURE

15

0

SFR

Effective Address

1

1

1

1

1

1

1

8 7

0

7

OP code

sfr-offset

1

5.4.5 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 be accessed with short direct addressing.

[Operand format]

Identifier

Description

sfr

Special-function register name

sfrp

16-bit manipulatable special-function register name (even address only)

[Description example]

MOV PM0, A; when selecting PM0 (FF20H) as sfr

Operation code

1 1 1 1 0 1 1 0

OP code

0 0 1 0 0 0 0 0

20H (sfr-offset)

[Illustration]

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