2 register addressing – NEC uPD78P078 User Manual
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CHAPTER 5 CPU ARCHITECTURE
0 1 1 0 0 0 1 0
Register specify code
Operation code
5.4.2 Register addressing
[Function]
The general register is accessed as an operand. The general register to be accessed is specified with register
bank select flags (RBS0 and RBS1) and register specify code (Rn, RPn) 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 operation code.
[Operand format]
Identifier
Description
r
X, A, C, B, E, D, L, H
rp
AX, BC, DE, HL
‘r’ and ‘rp’ can be described with function names (X, A, C, B, E, D, L, H, AX, BC, DE and HL) as well as absolute
names (R0 to R7 and RP0 to RP3).
[Description example]
MOV A, C; when selecting C register as r
INCW DE; when selecting DE register pair as rp
1 0 0 0 0 1 0 0
Register specify code
Operation code