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From: rob@uokmax.ecn.uoknor.edu (Robert K Shull)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.misc
Subject: Re: Question on Removable HD
Message-ID: <1991Jan3.152248.29582@uokmax.ecn.uoknor.edu>
Date: 3 Jan 91 15:22:48 GMT
References: <1990Dec31.181853.28607@bronze.ucs.indiana.edu> <1991Jan2.215035.17901@uokmax.ecn.uoknor.edu> <1991Jan2.232147.4576@agate.berkeley.edu>
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK
Lines: 25

In article <1991Jan2.232147.4576@agate.berkeley.edu> steve@violet.berkeley.edu (Steve Goldfield) writes:
>
>The problem, as I understand it, is that the Mac does
>not like to have an SCSI device plugged in but not
>powered on. I don't think it depends on the type of device.

It depends on which model of Mac you have, and what kind of SCSI device.
My understanding of the situation is this:
Some Macintosh models supply terminator power through the SCSI port (at
least Macintosh II and beyond). Some SCSI devices pass this terminator
power through when they are powered off, and some don't. So, if you have
a Mac that supplies terminator power, and a device that passes it through,
you can leave that device off (or turn it off) while you use your Mac.
If you don't, you'll end up with an unterminated bus and nothing will show.

I have a Mac II with Rodime internal and APS Syquest external. Everything
works fine with the external off or on. Now, I just added an Apple CD-ROM.
Boom. Nothing works with the CD off, even if it's the only external device.
Phttht. I think I'll open up the case and take a look at it, when the
warranty expires.

	Robert
-- 
Robert K. Shull
rob@uokmax.ecn.uoknor.edu				chinet!uokmax!rob