PM9500 Scsi type?

What do you mean...the internal scsi bus?
If so, it's the same scsi of all Macs of that era, which is 50-pin, not 80.

The internal-only bus is narrow and fast (50pin and 10MB/s) and the external/internal bus is narrow and not fast (50pin and 5MB/s.)

As a general rule, you should only use one wide 68/80pin device on a 50pin bus and it must be the last device and _must_ be terminated across the full wideness of itself (not just the 50 pin part.) An 68/80 pin device of course requires an adapter. An 80pin-50pin adapter must have termination built-in. A 68pin device could use built-in termination (on the drive), or could use an external term on the 68pin cable (at the end of course), or the 68-50pin adapter could include termination.

heh, hth,

dan k

sorry about being such a newb, lol. I didn't start really working on macs until the beige g3 era forward (as someone who fixes them). I guess I'll have to get used to the scsi way of thinking. the only scsi based devices i've used are external and provide their own power for termination. would this be okay for adapting current scsi drives over? http://cgi.ebay.com/NEW-SCA-adapter-80-pin-to-SCSI-I-II-III-68-50_W0QQitemZ370041632102QQihZ024QQcategoryZ31494QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The adapter you reference doesn't include built-in termination, but it ought to work if you add a terminator to the 68pin connector.

The 80/68 to 50 adaptation thing can be a real hair-puller, just expect to do some fiddling if (when?) it doesn't work immediately. SCSI has traditionally seemed more of an art than a science, though following the rules and using high-quality components usually has things working sooner than later.

dan k

haha, I look forward to becoming an PPC mac guru sooner or later. Guess this is a good first step ;-)