CPX                  CPX Compare Memory and Index X                   CPX

  Operation:  X - M                                     N V - B D I Z C
                                                        / . . . . . / /

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Immediate     |   CPX #$FF            |   $E0   |    2    |    2     |
  |  ZeroPage      |   CPX $FF             |   $E4   |    2    |    3     |
  |  Absolute      |   CPX $FFFF           |   $EC   |    3    |    4     |
  +----------------+-----------------------+---------+---------+----------+
  For penalty cycles on the 65816, check the desired addressing mode.