I have a driver, but it is for BSD/OS. :-)  (It needs some more work
before it is ready for prime time... it reads and writes but I am
sure formatting will fail.  It is also not tested on the 82077.)

>Specificly, has anyone information on:
>        - how to turn a drive's motor on

It is magic, it turns on when you do an operation and turns off
again by itself.

>        - how to configure the device FIFO buffer (for PIO)

Just as on the 82077, I believe.  I did get a magic byte of 0x64
for configuration paramater 0 (the `motor config') which I have yet
to figure out what it means.

You will need a trap-window interrupt handler.  I wrote mine in C
initially and it was way too slow; I always got fifo overruns.

>        - how to set implied seek (if this is at all useful; the
>          82077 seems to have it)

Dunno, I do explicit seeks.

Chris