PHX                     PHX Push Index X on Stack                     PHX

 65816 only!
                                                        N V M X D I Z C
  Operation:  X-Ws, S-2 -> S                            . . . . . . . .

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  | Implied/Stack  |   PHX                 |   $DA   |    1    |    3/4   |
  +----------------+-----------------------+---------+---------+----------+
  For penalty cycles on the 65816, check the desired addressing mode.