Register Addressing - NEC 78K0 User Manual

3.4.2

Register addressing

[Function]
The general-purpose register to be specified is accessed as an operand with the register bank select flags
(RBS0 to RBS1) and the register specify codes (Rn and RPn) of an operation 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]
'r' and 'rp' can be described by 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 C register as r
Operation code
INCW DE; when selecting DE register pair as rp
Operation code
88
CHAPTER 3 CPU ARCHITECTURE
Identifier Description
r X, A, C, B, E, D, L, H
rp AX, BC, DE, HL
0 1 1 0 0 0
*
1 0 0 0 0 1
User's Manual U15947EJ2V0UD
1 0
Register specify code
0 0
Register specify code