> Has anyone considered prototyping this PIO/IDE interface in Simh?

I hadn't; at the time I didn't know of simh.  Now that you've mentioned
it, I doubt it would help; the simh simulation would do only what the
simulator module's author thinks the card should do, not what it
actually does.  (It would help, perhaps, with initial software
development, but that hurdle has already been passed, at least with
respect to chd's implementation.  The code I had worked well enough to
probe and attach wd0 and wd1; it just didn't work to do much with
them.)

/~\ The ASCII				der Mouse
\ / Ribbon Campaign
 X  Against HTML	       mouse@rodents.montreal.qc.ca
/ \ Email!	     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B