assigned by RISCOS Ltd (and were assigned by Acorn) to be unique across all
manufacturers. This means that associating each one with a manufacturer (and
checking the manufacturer when attaching) is bogus. Thus, we don't do that
any more.
This should have the pleasant side-effect of getting APDL IDE interfaces
working, since they're just ICS ones with a different manufacturer ID.
Currently it appears as a "com" port, which is less than useful, and
occasionally generates stray interrupts. "stty -f /dev/tty00 31250 raw"
does enable it to talk to a nearby MIDI device, though.