> I don't know about the Shadow Quadralink, but mine has two Zilog Z8530
> UARTs (Z85C3008PSC to be exact...).  There are no other major chips on
> the board (eg, no CPUs).

Sounds pretty simple.

> Using MacsBug and the Slots program, I've located the control and data
> registers on the UARTs, and know how to read these off the card via
> the sResource dir.  That's as far as I've gotten so far, though.

Cool.  That's a good start.  Something else to figure out is where the
interrupts come in.  You get one interrupt for the nubus slot, so you'll
have to figure out which chip (or both, perhaps) is (are) interrupting.
It may be that you just have to read RR3 on both chips to figure it out.

In any case, you probably will want to (if at all possible) use the M.I.
zs driver and just write the machine-dependent front-end for it (as
Ken(?) suggested).

-allen