     $D0B5/53429/SCPU+69:   JiffyDOS-/Speed Switch Flag

       +-------+--------------------------------------------------------+
       | Bit 7 |   JiffyDOS Switch Flag: 1 = Enabled                    |
       | Bit 6 |   Speed Switch Flag: 1 = 1 MHz                         |
       +-------+--------------------------------------------------------+

         This register is read only with hardware registers enabled or
         disabled (write with hardware registers enabled has no effect).