5 register indirect addressing – NEC switch User Manual

Page 55

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CHAPTER 3 CPU ARCHITECTURE

User’s Manual U12978EJ3V0UD

55

3.4.5 Register indirect addressing

[Function]

In the register indirect addressing mode, memory is manipulated according to the contents of a register pair

specified as an operand. The register pair to be accessed is specified by the register pair specification code

in an instruction code.

This addressing can be carried out for all the memory spaces.

[Operand format]

Identifier

Description

[DE], [HL]

[Description example]

MOV A, [DE]; When selecting register pair [DE]

Instruction code

0

0

1

0

1

0

1

1

[Illustration]

15

0

8

D

7

E

0

7

7 0

A

DE

Addressed memory
contents are
transferred

Memory address
specified with
register pair DE

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