NEC UPD789026 Series, User Manual

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CHAPTER 3 CPU ARCHITECTURE
User's Manual U11919EJ3V0UM00
66
3.4.4 Register addressing
[Function]
The general-purpose register is accessed as an operand. The general-purpose register to be accessed is
specified with register specification code and functional name in the instruction code.
Register addressing is carried out when an instruction with the following operand format is executed. When an
8-bit register is specified, one of the eight registers is specified with 3 bits in the instruction code.
[Operand format]
Identifier Description
r X, A, C, B, E, D, L, H
rp AX, BC, DE, HL
'r' and 'rp' can be written with absolute names (R0 to R7 and RP0 to RP3) as well as function names (X, A, C,
B, E, D, L, H, AX, BC, DE, and HL).
[Example]
MOV A, C; When selecting the C register for r
Instruction Code 0 0 0 0 1 0 1 0
0 0 1 0 0 1 0 1
Register Specification Code
INCW DE; When selecting the DE register pair for rp
Instruction Code 1 0 0 0 1 0 0 0
Register Specification Code
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