Difference between revisions of "PM Opc NEG"
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Latest revision as of 12:49, 27 March 2010
NEG = Negate
Hex | Mnemonic | Cycles |
---|---|---|
CE A4 | NEG A | 12 |
CE A5 | NEG B | 12 |
CE A6 nn | 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 bit 7 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)