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From: jmb@patton.sgi.com (Jim Barton)
Newsgroups: comp.periphs
Subject: Re: SGI IRIS 80GTB SCSI bus problem solved
Message-ID: <43065@sgi.sgi.com>
Date: 16 Oct 89 15:23:32 GMT
References: <12249@cit-vax.Caltech.Edu>
Sender: jmb@patton.sgi.com
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 38

In article <12249@cit-vax.Caltech.Edu>, tim@cit-vax.Caltech.Edu (Timothy L. Kay) writes:
> 
> I recently posted that we were having trouble when we tried to
> hang too many devices (6) off the 80GTB SCSI bus.  I got many
> very useful responses, and lots of good information.
> 
> It turns out that I made a bad assumption.  I had assumed that Silicon
> Graphics would ship their $100,000 machine configured correctly!  It
> turns out that they sent it out with too many terminators already on
> the bus!!!  When I added our drives, I very carefully removed the
> terminators that were supposed to be there (on the disk drive), but I
> failed to remove the terminators on the SGI supplied tape drive.  Thing
> is that they should never have been there in the first place!!!
> 
> Grrrrr.
> 
> Tim

Grrrrr yourself.  The 80GTB was configured correctly.  The bus has to be
terminated somewhere.  To ease manfucturing, we always set up the tape drive
as the last device on the bus and terminate it, that way the folks who
bolt the machines together can do it with fewer errors.

When you add device on the bus AFTER the tape drive, you are doing something
even our FE's are trained not to do: they also will move the tape drive to
last on the bus for simplicity.  If you have NO terminators on your bus
now, you are also violating the SCSI specification; I hope the data goes
out to your disk realiably!

Don't bash us when you do it yourself.  Your take your own risks.

-- Jim Barton
Silicon Graphics Computer Systems    "UNIX: Live Free Or Die!"
jmb@sgi.sgi.com, sgi!jmb@decwrl.dec.com, ...{decwrl,sun}!sgi!jmb

  "I used to be disgusted, now I'm just amused."
			- Elvis Costello, 'Red Shoes'
--