dec

Operands

dec r | dec rr | dec (rr) | dec (ii+dd)

Subtracts one from B.

Every form of dec the assembler accepts. The cycles column counts clock cycles, written as taken/not taken for the conditional forms.

Instruction	Description	Flags	Bytes	Cycles
dec b	Subtracts one from B.	N=1P/V=VHZS	1	4
dec bc	Subtracts one from BC.	—	1	6
dec c	Subtracts one from C.	N=1P/V=VHZS	1	4
dec d	Subtracts one from D.	N=1P/V=VHZS	1	4
dec de	Subtracts one from DE.	—	1	6
dec e	Subtracts one from E.	N=1P/V=VHZS	1	4
dec h	Subtracts one from H.	N=1P/V=VHZS	1	4
dec hl	Subtracts one from HL.	—	1	6
dec l	Subtracts one from L.	N=1P/V=VHZS	1	4
dec (hl)	Subtracts one from (HL).	N=1P/V=VHZS	1	11
dec sp	Subtracts one from SP.	—	1	6
dec a	Subtracts one from A.	N=1P/V=VHZS	1	4
dec ixh undocumented	Subtracts one from IXH.	N=1P/V=VHZS	2	8
dec ix	Subtracts one from IX.	—	2	10
dec ixl undocumented	Subtracts one from IXL.	N=1P/V=VHZS	2	8
dec (ix+dd)	Subtracts one from the memory location pointed to by IX plus `dd`.	N=1P/V=VHZS	3	23
dec iyh undocumented	Subtracts one from IYH.	N=1P/V=VHZS	2	8
dec iy	Subtracts one from IY.	—	2	10
dec iyl undocumented	Subtracts one from IYL.	N=1P/V=VHZS	2	8
dec (iy+dd)	Subtracts one from the memory location pointed to by IY plus `dd`.	N=1P/V=VHZS	3	23