SED                       SED Set decimal mode                        SED
                                                        N Z C I D V
  Operation:  1 -> D                                    . . . . 1 .
                                (Ref: 3.3.1)
  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Implied       |   SED                 |   $F8   |    1    |    2     |
  +----------------+-----------------------+---------+---------+----------+