Design flaw in the SCSI spec?

jim stephens jwsmail at
Wed Jan 8 17:44:00 CST 2020

On 1/8/2020 9:54 AM, Liam Proven via cctalk wrote:
> With his express permission, I'm forwarding a mail from a public list.
> I am interested in Gene's comments about the design of SCSI, but I
> don't know enough electronics to judge.
> I thought others here might.
> I have trimmed the mail a little to the relevant parts.
The electronics of the SCSI interface were designed initially by the 
precursor to Adaptec.  At the time that the SCSI committee was formed, 
there was work by a number of companies.  Among them were HP, and the like.

I know the design for the 40mhz flavor was done by Emulex with Bill 
Roberts, one of the founders involved in the design work at Emulex.

I'm not sure that bean counters factored into anything there, but 
business did, as Emulex saw dominating the parallel bus market emerging 
as SCSI as a critical goal for the corporation.

I went to an ANSI meeting with Bill Roberts when he presented work that 
Emulex did that defined the 20mhz flavor.  Thru the process of the 
definition of SCSI-I there was a continuous evolution of the performance 
of the bus, and of the protocol to best exploit the additional performance.

The one thing that I do recall was that AMP would always be present with 
a new and wonderful connector tweak or design if needed.  They got to 
supply the bulk of the product as a result.


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