Timer C = Rx baudrate, Timer D = Tx baudrate, Timer A/B = Not used
  General Purpose pins I0..I7 are wired as so:
  I0=DTR, I1=RTS, I2=CTS, I3=DSR, I4=CHRDET(aka DCD), I5-I7=NC
  INT output is not connected to CPC
Also used by Tim Riemann's DIY schematic:
  Exactly same as Schneider RS232 Interface, except that,
  Port F8E0h..F8EFh are fixed (no jumpers for other port addresses)
  I4=NC (no CHRDET /DCD support)
== Register Summary ==