$DE00/56832/RR+0:   Control-Register

  On read:

   +-------+--------------------------------------------------------+
   | Bit 7 |   ROM bank selector (A15)                              |
   | Bit 6 |   1 = REU compatible memory map active                 |
   | Bit 5 |   ROM bank selector (A16)                              |
   | Bit 4 |   ROM bank selector (A14)                              |
   | Bit 3 |   ROM bank selector (A13)                              |
   | Bit 2 |   1 = Freeze button pressed                            |
   | Bit 1 |   AllowBank bit (see $DE01 / Write)                    |
   | Bit 0 |   1 = Flashmode active (jumper set)                    |
   +-------+--------------------------------------------------------+

  On write:

   +-------+--------------------------------------------------------+
   | Bit 7 |   ROM bank selector (A15)                              |
   | Bit 6 |   1 = exit from Freeze mode (if not in, no effect)     |
   | Bit 5 |   0 = select ROM, 1 = select RAM                       |
   | Bit 4 |   ROM bank selector (A14)                              |
   | Bit 3 |   ROM bank selector (A13)                              |
   | Bit 2 |   1 = disable cartridge                                |
   | Bit 1 |   1 = /EXROM high                                      |
   | Bit 0 |   1 = /GAME low                                        |
   +-------+--------------------------------------------------------+

      Default value is $00(%00000000) ($02 (%00000010) when Flashmode active).