SED                       SED Set decimal mode                        SED

  Operation:  1 -> D                                    N V - B D I Z C
                                                        . . . . 1 . . .

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Implied       |   SED                 |   $F8   |    1    |    2     |
  +----------------+-----------------------+---------+---------+----------+