Nintendo DMG-01 - Game Boy Console Manual page 89

TM
Game Boy CPU Manual
10. DEC n
Description:
Decrement register n.
Use with:
n = A,B,C,D,E,H,L,(HL)
Flags affected:
Z - Set if reselt is zero.
N - Set.
H - Set if no borrow from bit 4.
C - Not affected.
Opcodes:
Instruction
DEC
DEC
DEC
DEC
DEC
DEC
DEC
DEC
by DP
Parameters
A
B
C
D
E
H
L
(HL)
Opcode Cycles
3D 4
05 4
0D 4
15 4
1D 4
25 4
2D 4
35 12
3.3.3. 8-Bit ALU
Page 89