SUB

Sub stands for subtract but only takes one input. It subtracts the input from the accumulator and writes back to it.

Syntax

sub op8        ;8 bit

Allowed Instructions

sub a
sub b
sub c
sub d
sub e
sub h
sub l
sub n        ;8 bit constant

sub (hl)
sub (ix+n)
sub (iy+n)

Effects

N flag set, P/V is overflow, rest modified by definition.

Uses

Allows you to subtract two 8 bit integers. Useful in if you have an offset and want to eliminate certain items.

noGood:
 bcall(_GetKey)
 sub kAdd        ;get rid of all keys above add
 jr nc,noGood

T-States

r denotes 8-bit register.

r	4
X	7
(hl)	7
(ix+X)	19
(iy+X)	19

See Also

ADC,ADD,DAA,DEC,INC,SBC