TYS                TYA Transfer index Y to stack register             TYS

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

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Implied       |   TYS                 |   $2B   |    1    |    1s    |
  +----------------+-----------------------+---------+---------+----------+
  s Instruction requires 2 cycles when CPU is run at 1 MHz or 2 MHZ