I recall the 2GB volume limit, and the Apple ROM to format issue, but wasn't sure exactly where System 7 or the IIsi fit into that Apple timeline.

And thank you very, very much for the clear and specific SCSI drive and power tech tips. They'll be very useful going forward. (If I'm lucky it looks like I might be able to get a drive locally - untested - pulled years ago from an early Power Mac. I suppose it'd be 50pin somewhere from 500MB-2GB, unless it was an upgrade.)

It'll be nice to get a backup drive ready to swap in if the need arises...