In case you have an old world Mac clone (i.e. Power Computing) on which
you'd like to run MacOS 9 and/or Linux and in case the original CD-ROM
(i.e. NEC) does not work (meaning you can boot from it but can't mount a CD
once you booted from the hard disk): not all is lost.
One solution is to replace the CD-ROM with an Apple one. If you live in the
SFO Bay Area, there is a place where you can find old Apple CD-ROM drives
with Firmware from 1993 to 1995 (they aren't fast but they work). I tried
the ones from 1995 but not the earlier ones. Prices vary from $2.95 to
$7.95. There is no guaranty that they are still functional, but you have 30
days to return them.
The place is called "WeirdStuff", to find its location go to
http:/www.weirdstuff.com. Anyway, it's an interesting place to visit where
you can find things that may even pre-date some of you. Apple II disk
drives for instance. You can even buy a MacPlus for $10 if that's your
thing. For the grown-ups, it's a trip on memory lane.
Most of their stuff is for PCs, but if you dig deep enough in the back store
you'll find Macintosh things (such as plastic sliding hard disk brackets,
50 cents a piece).