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From: kaufman@Neon.Stanford.EDU (Marc T. Kaufman)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Mac+ SCSI termination problem!HELP!
Message-ID: <1990Nov8.172338.18906@Neon.Stanford.EDU>
Date: 8 Nov 90 17:23:38 GMT
References: <17010@shlump.nac.dec.com>
Organization: Computer Science Department, Stanford University
Lines: 23

In article <17010@shlump.nac.dec.com> phil@vaxphw.enet.dec.com (Phil Hunt) writes:

.I have an external hard disk, terminated in the drive.  I plug it into a
.Mac IIcx and it works perfectly, boots, plays, etc.  No problem.

.But I plug it into a MacPlus, it isn't recognized.  I run SCSIProbe CDEV and it
.reports, 'Bus Not Terminated'.   I even plugged unterminated it, then plugged
.another drive in after it and terminated there, still 'Bus Not terminated'.

.What am I doing wrong?

You aren't doing anything wrong, exactly.  The Mac Plus does NOT provide
power for the terminators (unlike the II series).  This means that you should
use INTERNAL terminators in your drive (or in the drive you plug into your
first drive).  Internal terminators are (usually) powered by the drive itself.
Very occasionally, one finds a drive that can be configured to provide power
to external terminators.  If yours can, you can do that and continue to use
the external terminator.

For a single drive, with a short cable, on a Plus, you can probably get away
with using NO terminators at all.

Marc Kaufman (kaufman@Neon.stanford.edu)