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From: dwhite@anshar.shadow.net (Don Whiteside)
Newsgroups: comp.unix.bsd.freebsd.misc,comp.periphs.scsi
Subject: Re: Adaptec 1542C for $125CDN -- comments?
Followup-To: comp.unix.bsd.freebsd.misc,comp.periphs.scsi
Date: 3 Jul 1995 11:47:36 -0400
Organization: Shadow Information Services, Inc.
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References: <rrwood-2106951636420001@bpci.net3.io.org> <3skl1s$56l@natasha.rmii.com> <3smdbn$ml0@bonnie.tcd-dresden.de> <DAy5Et.8uD@watserv1.uwaterloo.ca> <3t01b9$m0i@panix.com>
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John Brock (jbrock@panix.com) wrote:
: In article <DAy5Et.8uD@watserv1.uwaterloo.ca>,
: >I have read about this, and for now, it isn't too much of a concern
: >since I do have 16megs of RAM and the 1542CF. But I was thinking of upgrading
: >my memory soon, so what will happen ? Is there any way to get around this
: >16meg ram problem ? If so, what consequences are there ?
: I asked about this a little while ago (prompted by a comment in the
: Linux SCSI HOWTO), and came to the conclusion that this is a phony
: problem. There is a 16MB limit for DMA, but the problem is taken care
: of in the drivers, which is really what you would expect anyway. It
: hardly makes sense that Adaptec or anybody would make a high end SCSI
: card that wouldn't work with a high memory PC.
Phony problem? Well, I guess that depends on how you think of it. If you
mean in the sense that it will still work, sure, it's a phony problem.
If, however, you're one of those unreasonable people like me who thinks
that an expensive card that is supposed to perform at high speed _should_
perform at high speed, then it _is_ a problem.
This is not a slight against Adaptec - it's not their fault the bus was
shortsightedly designed. But the fact is that if you want the full speed
out of the card, you need to stay in 16M of RAM. The bounce buffers
_work_, but they are not as fast.
So if you want to talk about "sense," the last of sense is not Adaptec,
but the original designers of the PC. (Or, perhaps more accurately, that
so many of us have clung stubbornly onto obsolete designs)
=========================================================================
Donald Alan Whiteside MDCC Wage Slave School of Computer Science
Official Usenet Dork for the week of Jan 9-13, 1995
GCS d-- -p+(---) l u+(-) e+ m+ s !n h f g+ w+ t+(++) r- y++
"The universe is not in the habit of giving up
explanations to cursory examinations" - Garth Thornton
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