CHAPTER 3 CPU ARCHITECTURE
Preliminary User’s Manual U16846EJ1V0UD
56
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]
Identifier Description
r
X, A, C, B, E, D, L, H
rp
AX, BC, DE, HL
‘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
0
1
1
0
0
0
1
0
Register
specify
code
INCW DE; when selecting DE register pair as rp
Operation code
1
0
0
0
0
1
0
0
Register
specify
code