$D030/53296/VIC+48:  C128 only: Switch to FAST-Mode

   +----------+---------------------------------------------------+
   | Bits 7-2 |   no Function, always 1                           |
   | Bit  1   |   1 = Test-Mode(?)                                |
   | Bit  0   |   1 = FAST-Mode enabled                           |
   +----------+---------------------------------------------------+