Assembly Language Help (alang.hlp) (Table of Contents; Topic list)
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CMPXCHG Instruction
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  Title:    Compare and Exchange                  Flags: O D I T S Z A P C
            80486 Only                                   ═════════════════
                                                         ±       ± ± ± ± ±
  Syntax:   CMPXCHG dest,src
 
  See also: .486, CMP, XCHG
 
  Description:
 
     Compares the destination operand to the accumulator (AL, AX, or
     EAX). If equal, the source operand is copied to the destination.
     Otherwise, the destination is copied to the accumulator. The
     instruction sets flags according to the result of the comparison.
                                    -♦-