[Coco] Turbo DriveWire

[Aaron Wolfe]

A few days back I asked for help with the DriveWire project, and boy
did I get some :)

In addition to suggestions, advice and offers of future assistance
from several coconuts, Darren Atkinson has tweaked the bitbanger I/O
routines to work at a blazing 230Kbps.  If I understand it correctly,
this will also allow 115k operation on CoCo 2s, up from 57.6k.   I've
been testing it this weekend and it's a substantial improvement in
performance, in fact in the "Donkey Load" test being discussed over on
Brian's forum, it beats all other systems tested by a good measure.

I want to publicly thank Darren not only for this contribution but
also for doing so much for so many projects in the CoCo realm, often
behind the scenes.  The MCX128 expander for the MC-10 is very cool,
and I can't wait to see the upcoming drive emulator.   Awesome stuff
all around.

-Aaron