Rabbit 2000 - Page 33

Instruction Reference Manual 29
Description
Decrements the data in index register IX or IY.
Description
Decrements the data in the register r (any of the registers A, B, C, D, E, H, or L).
DEC IX
DEC IY
Opcode Instruction Clocks Operation
DD 2B DEC IX 4 (2,2) IX = IX - 1
FD 2B DEC IY 4(2,2) IY = IY - 1
Flags ALTD I/O
S Z L/V C F R SP S D
- - - -
DEC r
Opcode Instruction Clocks Operation
——
3D
05
0D
15
1D
25
2D
DEC r
DEC A
DEC B
DEC C
DEC D
DEC E
DEC H
DEC L
2
2
2
2
2
2
2
2
r = r -1
A=A-1
B=B-1
C=C-1
D=D-1
E=E-1
H=H-1
L=L-1
Flags ALTD I/O
S Z L/V C F R SP S D
• • V - • •