+------------------------------------------------------------------------
  |
  |      TURBO232, SWIFTLINK AND COMPATIBLES
  |
  +------------------------------------------------------------------------
  |
  | (Note: Other Base-Addresses may be: $D700/55040 or $DF00/57088)
  |
  |   $DE00/56832/SWIFTLINK+0        Data Register
  |   $DE01/56833/SWIFTLINK+1        Status Register
  |   $DE02/56834/SWIFTLINK+2        Command Register
  |   $DE03/56835/SWIFTLINK+3        Control Register
  |   $DE04/56836/SWIFTLINK+4        Undefined Register
  |   $DE05/56837/SWIFTLINK+5        Undefined Register
  |   $DE06/56838/SWIFTLINK+6        Undefined Register
  |
  | Turbo-232 only:
  |
  |   $DE07/56839/TURBO232+7         Enhanced-Speed Register
  |
  +------------------------------------------------------------------------