SCAM on LDV (round 2)

Skip Jones sk_jones at
Fri Oct 25 10:45:20 PDT 1996

* From the SCSI Reflector (scsi at, posted by:
* "Skip Jones" <sk_jones at>

'Which' agenda will you add this topic to?  I will not be attending Palm
Springs until late afternoon Wednesday.  I'm sending someone else (Tom Jones -
No!  Not the damn singer!) and I want to ensure he is there for all of Monday
and 'maybe' Tuesday depending on what topics will be discussed Tuesday.


Skip Jones

PS:  By the way, the topics George and others have been bringing up may be real
or not, but I promise you they do relect some of the concerns/perceptions of a
lot of people out there.  I appreciate that Symbios is doing what they can do
to redefine and further segment the market since you guys are about a 6 months
early with LVD (I'd do the same in your shoes!).  But, I see some hesitation,
sometimes based on fear of change, sometimes as a result of confusion, and in
many cases based on hard cold facts.  We are all doing LVD and by this time
next year we all plan for LVD to be a significant portion of product shipped
(albeit not always 'used').  So, it behoofs all of us to surface all of these
issues as quickly as possible, real or not, and address these issues either by
education, standards modifications, technical reports, or engineering design. 
This SCAM topic is a perfect example.  It may seem like a non-issue to Symbios,
but if its not intuitive to Mr. Penokie how its a non-issue, and knowledgeable
folks like him are asking these questions, then surely you would agree that
there are a whole lot more people out there that are wondering the same and
even more about LVD?  If respected members of our own little T10 committee have
questions and concerns, imagine the level of questions, concerns, and confusion
emitting from the rest of the much larger industry!!  Just a thought.
From: Lohmeyer, John on Thu, Oct 24, 1996 11:58 AM
Subject: RE: SCAM on LDV (round 2)
To: 'SCSI Reflector'

* From the SCSI Reflector (scsi at, posted by:

George wrote:
>What, no comments on SCAM being usable on LDV!!!  Did everyone leave the
>country or what.  Could it be that there just is no interest in SCAM on   
>Many think LVD is the furture of SCSI which implies there is no SCAM in
>the future. It seems to me the only logical thing to do would be to
>elimiate SCAM altogether or to removed it from SPI and make it in to
>a tecnical report.

Not so fast, George.  SCAM should work perfectly fine on LVD.  There is   
no reason the LVD drivers cannot be operated in wired-OR mode (they   
already are required to operate in wired-OR mode on the RST, BSY, and SEL   
signals).  SCAM operates several more signals in wired-OR mode and it   
needs to be able to both drive and receive these signals at the same   
time.  Otherwise, SCAM demands nothing of the drivers and receivers that   
normal SCSI does not demand.

SCAM should also work fine on HVD, but I do not know of any   
implementations because SCAM support for HVD requires way too many pins   
on the protocol chip to support the external transceivers.  LVD solves   
this problem by putting the drivers and receivers on the protocol chip.

>This topic should be placed on the agenda for Palm Springs.

I'll add it if you want, but I think there is very little to discuss.


PS: All of the announced and shipping LVD silicon in the worId already   
supports SCAM.

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

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