Okay this one has me stumped. For reasons I can't workout (its probably something very simple Ive missed), my PowerMac 8600/250 will only boot from its Secondary HDD with System 7.5.3 on from Cold, ignoring the larger, original system drive with 8.1 on it, however once up it can reboot and start fine from the 8.1 HDD. (They are not partitions, but physically separate SCSI disks). Anybody remember how to persuade a old Beige Mac to play nice with 2 HDDs? (For those interested, this 8600 is still in production-ish use, with a redundant 7500 with AV just in case. I use it for grabbing stills and short clips from archival material on VHS in AVID/Strata VideoShop 3).
It should be noted the 7500/132 (the card is from a 7600, so its basically a 7600/132 with the wrong number on the front) runs just fine with 2 HDDs in what is identical software wise and appears identical configuration wise.
It should be noted the 7500/132 (the card is from a 7600, so its basically a 7600/132 with the wrong number on the front) runs just fine with 2 HDDs in what is identical software wise and appears identical configuration wise.