JCXZ             Jump If CX Register Zero            Flags: not altered

JCXZ short-label

          Jump Condition:  Jump if CX = 0

    JCXZ transfers control to short-label if the CX register is 0. The
    target of the jump must be within -128 to +127 bytes of the next
    instruction.

  --------------------------------------------------------------------------
   Operands                  Clocks   Transfers  Bytes   Example
   short-label              18 or 6       -        2     JCXZ COUNT_DONE
  --------------------------------------------------------------------------

       Note:          This instruction is commonly used at the beginning
                      of a loop to bypass the loop if the counter variable
                      (CX) is at 0.