$D0B8/53432/SCPU+72:   Software 1 MHz-/Master 1MHz Flag

   +-------+--------------------------------------------------------+
   | Bit 7 |   Software 1 MHz Flag: 1 = 1 MHz                       |
   | Bit 6 |   Master 1 MHz Flag: 1 = 1 MHz via any source          |
   +-------+--------------------------------------------------------+

     This register is read only with hardware registers disabled,
     Read/Write with hardware registers enabled, write access reserved
     for system only.