PM Opc NEG

NEG = Negate

Hex	Mnemonic	Cycles
CE A4	NEG A	12
CE A5	NEG B	12
CE A6	NEG [N+#nn]	20
CE A7	NEG [HL]	16

Execute

A       = Register A
B       = Register B
[N+#nn] = Memory: (I shl 16) or (N shl 8) or #nn
[HL]    = Memory: (I shl 16) or HL

; NEG Ds
;
; Ds = Source/Destination

Ds = 0 - Ds

Description

8-Bits Destination is negated.

Conditions

Zero: Set when result is 0

Carry: Set when result is not 0

Overflow: Set when result is 0x80

Sign: Set when 7th bit of the result is 1

Examples

; A = 0x01
NEG A
; A = 0xFF (0 - 0x01 = 0xFF)
; F = (Zero = 0):(Carry = 1):(Overflow=0):(Sign=1)

; B = 0x00
NEG B
; B = 0x00 (0 - 0x00 = 0x00)
; F = (Zero = 1):(Carry = 0):(Overflow=0):(Sign=0)

; [HL] = 0x80
NEG [HL]
; [HL] = 0x80 (0 - 0x80 = 0x80)
; F = (Zero = 0):(Carry = 1):(Overflow=1):(Sign=1)

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