DEC

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

ADC,ADD,DAA,INC,SBC,SUB