Zilog Z80380 - Manual (Page 142)

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Z380 ™
U SER ' S M ANUAL
DC-8297-03
Z ILOG
NEG
NEGATE ACCUMULATOR
NEG [A]
Operation: A
←
-A
The contents of the accumulator are negated, that is replaced by its two’s complement
value. Note that 80h is replaced by itself, because in two’s complement representation the
negative number with the greatest magnitude has no positive counterpart; for this case, the
Overflow flag is set to 1.
Flags: S: Set if the result is negative; cleared otherwise
Z: Set if the result is zero; cleared otherwise
H: Set if there is a borrow from bit 4 of the result; cleared otherwise
V: Set if the content of the accumulator was 80h before the operation; cleared otherwise
N: Set
C: Set if the content of the accumulator was not 00h before the operation; cleared if the
content of the accumulator was 00h
Addressing Execute
Mode Syntax Instruction Format Time Note
NEG [A] 11101101 01000100 2