SEI                 SEI Set interrupt disable status                  SEI

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

  +----------------+-----------------------+---------+---------+----------+
  | Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
  +----------------+-----------------------+---------+---------+----------+
  |  Implied       |   SEI                 |   $78   |    1    |    2     |
  +----------------+-----------------------+---------+---------+----------+