JS               Jump If Sign                        Flags: not altered

JS short-label

          Jump Condition:  Jump if SF = 1

    JS transfers control to short-label if the Sign Flag is set. The
    target of the jump must be within -128 to +127 bytes of the next
    instruction.

  --------------------------------------------------------------------------
   Operands                  Clocks   Transfers  Bytes   Example
   short-label              16 or 4       -        2     JS NEGATIVE
  --------------------------------------------------------------------------

       Notes:         Use JNS, Jump if No Sign, to jump if the sign flag
                      is clear.