customer perspective RE: Mixed bus widths

Robert Palasek palasek at
Wed Oct 23 14:31:59 PDT 1996

* From the SCSI Reflector (scsi at, posted by:
* palasek at (Robert Palasek)
User/customer Perspective:
  A friend forwarded to me part of a discussion thread, copied below, which
was somewhat related to a recent problem.

  I have enjoyed SCSI and its benefits of being STANDARD for
a number of years.  Two weeks ago, when we bought a new desktop
computer, we weren't able to configure it because even though
our external cdrom devices were scsi, and even though the
computer had a scsi connector, they did not interoperate.

Marshal Rose explained one time that the reason the OSI standards, even though
they had the ability to solve problems that the internet is coming
up against just now,the reason they never proved useful to more than a few users
was because the standards committee never had the resolve to
say NO, that when there occurred a substantive difference, instead
of making a hard choice, they said, "we'll have it both ways."
How diplomatic!

I would worry that the same problem is going to kill scsi.
This is a plea for you to work hard to reduce the entropy.

In a more narrow view, my personal feeling is
that if generation N+1 does not deliver two orders
of magnitude improvement over generation N, you
should just wait and bide your time until it does.
Don't change it incrementally, the creep costs
more than its real value.

Ususal disclaimer: I am not speaking for
my employer nor its sponsors.
Bob Palasek
P.O. Box 808,  M.S. L-303
Livermore CA  94551.

>>From: "Lohmeyer, John" <JLOHMEYE at>
>>To: "'SCSI Reflector'" <scsi at Symbios.COM>
>>Subject: RE: Mixed bus widths
>>Date: Tue, 22 Oct 96 10:20:00 MDT
>>Encoding: 31 TEXT
>>Sender: owner-scsi at Symbios.COM
>>Precedence: bulk
>>* From the SCSI Reflector (scsi at, posted by:
>>Greg Alvey wrote:
>> ----------
>>>I seem to remember that there used to be something in the FAST-20
>>>that said something like: "the bus width shall be constant" (at least
>>>single ended).... but ...
>>>After reviewing Rev 6 of FAST-20, it appears to have "gone away".
>>>I guess I missed that one!  Maybe someone can inform us as to "when &
>>>I wonder if this statement was moved to another document (SPI or SPI-2
>>Your memory serves you well.  The statement was removed near the end of
>>the Fast-20 development when the working group went into "permissive
>>mode" (this is when the marketing people start reviewing the draft
>>document ;-).  No one knew for sure that mixed widths would cause
>>problems, so the restriction was removed.  About the same time we
>>softened much of the wording surrounding cable length restrictions.
>> --
>>John Lohmeyer                 E-Mail: john.lohmeyer at
>>Symbios Logic Inc.             Voice: 719-533-7560
>>4420 ArrowsWest Dr.              Fax: 719-533-7036
>>Colo Spgs, CO 80907-3444    SCSI BBS: 719-533-7950 300--14400 baud
>>* For SCSI Reflector information, send a message with
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