Zilog Z80380 Manual do Utilizador descarregar pdf (Página 143)

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Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

NEGW

NEGATE HL REGISTER (WORD)

NEGW [HL]

Operation: HL(15-0) ← -HL(15-0)

The contents of the HL register are negated, that is replaced by its two’s complement value.

Note that 8000h 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 HL register was 8000h before the operation; cleared otherwise

N: Set

C: Set if the content of the HL register was not 0000h before the operation; cleared if the

content of the HL register was 0000h

Addressing Execute

Mode Syntax Instruction Format Time Note

NEGW [HL] 11101101 01010100 2

1 2 ... 138 139 140 141 142 143 144 145 146 147 148 ... 267 268

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