TXS              TXS Transfer index X to stack pointer                TXS

  Operation:  X -> S                                    N V - B D I Z C
                                                        . . . . . . . .

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Implied       |   TXS                 |   $9A   |    1    |    2     |
  +----------------+-----------------------+---------+---------+----------+