22. Memory-to-memory exchange

• To exchange two memory operands, use a register as a temporary container and combine MOV with XCHG. For example,

      .DATA
          val1  WORD 1000h
          val2  WORD 2000h
  
      .CODE
          mov   ax,  [val1]   ; AX = 1000h
          xchg  ax,  [val2]   ; AX = 2000h, val2 = 1000h
          mov   [val1], ax    ; val1 = 2000h