From: ajc@pa.dec.com (AJ Casamento)
Newsgroups: comp.arch
Subject: Re: COMPAQ PROPOSED SCALABLE I/O ARCHITECTURE
Followup-To: comp.arch
Date: 11 Jan 93 16:42:59
Organization: Digital Equipment Corporation
	<AJC.93Jan4073719@thendara.pa.dec.com>
	<dbg-080193174652@kfp-slac-mac.slac.stanford.edu>
NNTP-Posting-Host: thendara.pa.dec.com
In-reply-to: dbg@slac.stanford.edu's message of Sat, 9 Jan 1993 02:09:00 GMT



David,

>>Gee, yet another opportunity to point out that the ANSI/IEEE Std 1596 SCI
>>Scalable Coherent Interconnect is just what you want!

Hmmm, I can think of a lot of things I "want", I'm not sure that SCI is among
them. However, it is possible that SCI might be something I "need" at some
point. ;-)

Thanks for the pointers on the various design tools/implementations.


>>But of course I understand that this discussion is futile--any engineer
>>worth his salt (salary) gets his only pleasure in life from designing his
>>own new unique solution to this problem! ;-)  Sigh.  But maybe his
>>competitors will have higher profits because they get the benefit of the
>>support infrastructure that grows around standards.


Certainly a lot of folks do get a charge out of developing something new, which
they can have some impact on. I would hazard a guess that this enjoyment might
have kept you going during what must have surely been some interminable IEEE
meetings in developing the SCI standard. No? I confess to enjoying this also,
though I also happen to be a fairly opportunistic character who will "borrow"
whatever technology/tool happens to fit the need. 

Standards can certainly be a good thing. It does not necessarily follow (at 
least for me) that therefore "all" standards are good. True SCI is an IEEE
standard. So too is Futurebus+, and Sbus, and VME. And SCSI is an ANSI standard
if we need an entry from that camp. My point is not to equate these to one
another or stipulate which is better. Just that they all have the attribute of
being a standard.

Obviously each of these protocols deserves to be judged on its own merit. I
also believe, personally, that standardization has its hazards. One can end up
with a standard like ANSI SCSI-1 which "grandfathered" a great deal of very
interesting behaviors into it based on products which were already shipping (it
was a problem in reaching any consensus that would make existing shipping SCSI
products non-compliant to the standard). Or, there is the "Profile" approach
that Futurebus+ has (Profiles: A,B,D,F,M,T) where you make the protocol fit a
wide variety of market uses by varying what the implementation looks like. I do
not offer any judgement on whether one is inherently better than the other. I
am also not certain that any one protocol is a "panacea" for all needs in the
market.

Your points on taking advantage of the volume/pricing of a popular standard are
well taken. However, a standard can become so by popular acclaim rather than
design by committee (as ISA did, or Sbus; which was popular long before it
gained IEEE status). And, SCI may become a popular standard that garners a high
volume of the market. I think it will be interesting to see what does happen.


Still just my own opinion, of course.

				Thanx,
				  AJ


      **********************************************************************
      * AJ Casamento			"The question is not whether or    *
      * Digital's TRI/ADD Program	 not the opinions are mine; but    *
      * 529 Bryant Ave. PAG-2		 rather, which of my personalities *
      * Palo Alto, CA 94301-1616	 do they belong to?"		   *
      * 415.617.3460							   *
      * ajc@pa.dec.com  						   *
      **********************************************************************