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From: peter@hari.Viewlogic.COM (Peter Colby)
Newsgroups: comp.sys.mac.hardware,comp.sys.mac.misc
Subject: Re: Question on Removable HD
Message-ID: <1991Jan3.111333@hari.Viewlogic.COM>
Date: 3 Jan 91 16:13:33 GMT
References: <1990Dec31.181853.28607@bronze.ucs.indiana.edu> <1991Jan2.215035.17901@uokmax.ecn.uoknor.edu> <1991Jan2.232147.4576@agate.berkeley.edu>
Sender: news@viewlogic.com (News Administrator)
Reply-To: peter@hari.Viewlogic.COM (Peter Colby)
Organization: Viewlogic Systems, Inc., Marlboro, MA
Lines: 47

In article <1991Jan2.232147.4576@agate.berkeley.edu>,
steve@violet.berkeley.edu (Steve Goldfield) writes:
|> In article <1991Jan2.215035.17901@uokmax.ecn.uoknor.edu>
rob@uokmax.ecn.uoknor.edu (Robert K Shull) writes:
|> #>In article <1990Dec31.181853.28607@bronze.ucs.indiana.edu>
daemon@copper.ucs.indiana.edu (Mr Background) writes:

..... much ado about being unable to boot with a SCSI drive powered
off.

|> 
|> 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.
|> My Mac won't boot in that situation either. However,
|> you shouldn't have to put a removable cartridge in
|> the drive to boot your Mac. You should only have to
|> have the power switch for the drive turned on.
|> 

There are a number of possible causes for a problem like this. Once
upon a time, when the Mac+ was still new, a version of the ROMs were
buggy to the point where the Mac wouldn't boot if a powered off device
was connected to the SCSI port.

Another possibility has to do with the way your device is terminated.
If your powered off device has it's terminator resistors connected to
the bus but drawing their power from the device, this will also kill
the SCSI bus.

As a final note; I have an (ancient) Mac+ with an external HD. My
SCSI terminators are on the HD itself (this is called internal
termination) and I can Still Boot when my HD is powered off. In
fact, this is the second HD I've owned with internal termination and
I had similar lack of problems with the first.

This is definitely a problem with your particular device, not with the
mac.

Peter C

DISCLAIMER: Hey, what do I know anyway!

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