CHAPTER 3 CPU ARCHITECTURE
3.4.4 Register addressing
[Function]
In the register addressing mode, general-purpose registers are accessed as operands. The general-purpose
register to be accessed is specified by a register specification code or 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
X, A, C, B, E, D, L, H
AX, BC, DE, HL
r
rp
r and rp can be described 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).
[Description example]
MOV A, C; When selecting the C register for r
Instruction code
1
0
0
0
1
0
0
0
Register specification code
INCW DE; When selecting the DE register pair for rp
Instruction code
0
0
0
0
0
1
0
0
1
0
0
1
1
0
0
1
Register specification code
74
User’s Manual U15075EJ1V0UM00
NEC [ NEC ]
