WDM                 WDM Reserved for Future Expansion                 WDM

 65816 only!
                                                        N V M X D I Z C
  Operation:  At the moment treated like NOP.           . . . . . . . .

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  | Immediate      |   WDM #$FF            |   $42   |    2    |     2    |
  +----------------+-----------------------+---------+---------+----------+
  WDM is the first byte of a multi-byte instruction set to be built in future
  versions of the processor. This instruction should NOT be used by now.
  (WDM -> William D. Mensch jr., 65816 designer)