[ On Mon, June 29, 1998 at 16:18:01 (-0600), Michael K. Sanders wrote: ]
> Subject: Differential SCSI?
>
> Does anyone have any opinions on using Differential SCSI?  I realize
> that the controllers are more expensive (~$350 for the 2944).

In my opinion the "common" single-ended SCSI bus electrical design is a
piece of crap and just as per the IEEE specs say -- it's a bloody wonder
it works at all at any speed.

The differential SCSI bus is indeed far superior, with better electrical
noise immunity, far longer maximum cable lengths, and fewer termination
problems.

I'm not an electrical engineer by trade, but I'm not entirely fresh off
the turnip truck either.  I've never had problems with busses using
differential signaling (eg. SMD drives with 50' of cable!), but I've had
no end of problems with single-ended SCSI.

I'll also note that all of the decent SCSI-based RAID sub-systems I've
researched in the past few weeks come only with differential host
interfaces.

-- 
							Greg A. Woods

+1 416 443-1734      VE3TCP      <gwoods@acm.org>      <robohack!woods>
Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>