z80:Opcodes:DEC
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Decreases operand by one.
Syntax
dec op8 ;8 bits dec op16 ;16 bits
Allowed Instructions
dec a dec b dec c dec d dec e dec h dec l dec ixh dec ixl dec iyh dec iyl dec (hl) dec (ix+n) dec (iy+n) dec bc dec de dec hl dec ix dec iy dec sp
Effects
8 Bits C flag preserved, P/V detects overflow and rest modified by definition.
16 Bits No flags altered.
Uses
T-States
r denotes 8-bit register. rr represents a two byte register pair: BC, DE, HL, SP
r | 4 |
(hl) | 11 |
(ix+X) | 23 |
(iy+X) | 23 |
rr | 6 |
ix | 10 |
iy | 10 |
See Also