80C186EB/80C188EB Microprocessor User's Manual - CEUNES

INSTRUCTION SET DESCRIPTIONSNEGNOPNOTNegate:When Source Operand is a Byte:NEG dest(dest) ← FFH – (dest)Subtracts the destination operand, (dest) ← (dest) + 1 (affecting flags)which may be a byte or a word, from 0 When Source Operand is a Word:and returns the result to the destination.This forms the two's(dest) ← (dest) + 1 (affecting flags)(dest) ← FFFFH – (dest)complement of the number, effectivelyreversing the sign of an integer. If theoperand is zero, its sign is notchanged. Attempting to negate a bytecontaining –128 or a word containing –32,768 causes no change to theoperand and sets OF.Instruction Operands:NEG regNEG memNo Operation:NOPCauses the CPU to do nothing.Instruction Operands:noneLogical Not:NOT destInverts the bits (forms the one'scomplement) of the byte or wordoperand.Instruction Operands:NOT regNOT memTable C-4. Instruction Set (Continued)Name Description OperationNOTE:AF üCF üDF –IF –OF üPF üSF üTF –ZF üNone AF –CF –DF –IF –OF –PF –SF –TF –ZF –When Source Operand is a Byte:(dest) ← FFH – (dest)When Source Operand is a Word:(dest) ← FFFFH – (dest)The three symbols used in the Flags Affected column are defined as follows:– the contents of the flag remain unchanged after the instruction is executed? the contents of the flag is undefined after the instruction is executedüthe flag is updated after the instruction is executedFlagsAffectedAF –CF –DF –IF –OF –PF –SF –TF –ZF –C-31