advansys scsi == ouch
Gene Heskett
gene.heskett at verizon.net
Sat Aug 28 06:15:42 UTC 2004
On Friday 27 August 2004 23:02, Les Mikesell wrote:
>On Fri, 2004-08-27 at 20:27, John McBride wrote:
>> What was
>> advansys thinking when they dropped the ball on kernel 2.6?
>> (rhetorical question).
>
>Maybe something like 'an operating system that changes the driver
>api's yearly will never catch on'?
>
>---
> Les Mikesell
> les at futuresource.com
Probably not. But I find it strange that no one has pointed out that
advansys themselves have been no more for what, 5 years now? To
expect a company to support their product 5 years after their demise
in the inevitable silicon valley money laundering is a bit
unrealistic.
I will give them credit for one thing that adaptec hasn't always
gotten right though, and thats truely proper termination setups. I
never, ever, had to sacrifice a virgin to make one of them work.
Nearly everyone else uses a gen purpose si diode in the host power
isolation position, rendering the intended logic 1 noise margin of
600mv into 100mv average when the stock resistive divider is used but
fed with an si diode. Advansys, at least on the card I have laying
here, appears to have used a schotkey diode for that. And they were
an early user of active terminations, a much more power miserly
method of trying to match the widely observed variations in the
actual impedance of the 'off the shelf' ribbon cable. That also
contributed to their success in that area.
Use a gp si diode for that like most card makers do, and you'll wind
up sacrificeing something to make it work 99.99%, the other .01%
being controlled by whatever gods you worship. Thats not great odds
in my betters manual. Yeah, I'm an RF engineer, and I do know what a
standing wave can do in a transmission line. Just because its a scsi
buss doesn't make it any less a transmission line in terms of its
electrical performance.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
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by Gene Heskett are:
Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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