>One other thing I'm going to throw out for those of you that know more
>about Macs and SCSI to pick apart is this:  the Quantum is I believe a
>SCSI-2 device, yet my Mac SE/30 I'm almost certain contains only a SCSI-1
>controller.  Would the SCSI-2 drive be attempting to detach itself from the
>SCSI bus and the reattach and thus cause SCSI Phase errors?  It seems a
>possibility to me with what I've been able to find out about SCSI on the
>Mac.  Also, can someone clear up exactly what SCSI Manager 4.3 is?  Is it a
>piece of software, like driver code or something that my SE/30 can be
>upgraded to (or may already have, since I'm running 7.5.5) or is it
>actually hardware on the Mac?

There shouldn't be any problems using a SCSI-2 device on a SCSI-1 chain.
This is akin to using a fast-SCSI device in a "regular" SCSI-2 chain. I
don't know much about OpenBSD, or if they have the same trouble with
NCR/SBC that we do, but that may be the trouble. I wouldn't think it would
be phase errors as much as file thrashing/corruption, though.

As far as SCSI manager 4.3, it's a driver standard that allows for asynch
data transmission. It was introduced with the Quadra 840 AV (& built into
its ROMs) and system 7.5 contained it in software form. The main advantage
to this is when you're trying to access 2 or more drives simultaneously (in
MacOS). Pre-4.3, the SCSI bus worked like a networked printer. It stored a
que & one job would print while the others waited. With 4.3, however, it
changed so that a request could be sent to multiple drives without waiting
for the rest of the first request to be fulfilled.

HTH
Mike

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