Yes, I am pretty sure the Mac disk controller can
write the 800K //gs
format (presumably it's similar to the Mac 800K format). I've never
tried
it,though, so I can't be absolutely sure.
It turns out I had one or two 800k disks from the days of my Macintosh
Plus. I tried writing IIgs software on one using my Quadra 650 and was
able to use it on my IIgs. I guess I'll just have to order more DSDD
720k disks rather than trying to mess around with HD disks with their
holes covered.
Thanks to everyone who responded to my question!
David