$DE03/56835/SWIFTLINK+3:   Control Register

   +----------+---------------------------------------------------+
   | Bit  7   |   Stop Bits: 1 = 2, 0 = 1 or 1.5                  |
   | Bit  6-5 |   Words: 00 = 8 Bit       10 = 6 Bit              |
   |          |          01 = 7 Bit       11 = 5 Bit              |
   | Bit  4   |   Baud Rate Generator: 1 = Internal, 0 = External |
   | Bits 3-0 |   Baud Rate: 0101 =  300 Bd      1011 =  7200 Bd  |
   |          |              0110 =  600 Bd      1100 =  9600 Bd  |
   |          |              0111 = 1200 Bd      1101 = 14400 Bd  |
   |          |              1000 = 2400 Bd      1110 = 19200 Bd  |
   |          |              1001 = 3600 Bd      1111 = 38400 Bd  |
   |          |              1010 = 4800 Bd                       |
   |          |              0000 = enable Enhanced Speed ($DE07) |
   +----------+---------------------------------------------------+