Path: utzoo!attcan!uunet!convex!killer!bigtex!james
From: james@bigtex.uucp (James Van Artsdalen)
Newsgroups: comp.unix.microport
Subject: Re: 386/ix: cpio to floppy panics kernel
Message-ID: <8884@bigtex.uucp>
Date: 6 Oct 88 02:36:50 GMT
References: <455@redsox.UUCP> <8254@alice.UUCP>
Reply-To: james@bigtex.UUCP (James Van Artsdalen)
Distribution: na
Organization: Dell Computers, Austin TX
Lines: 47

In article <8254@alice.UUCP>, debra@alice.UUCP () wrote:

[ discussion of bizarre memory problems with floppy/hard disk/DMA ... ]

> All these new cranked-up 286 and 386 boxes are pushing things BEYOND
> their limit.

I think the 310 designer would be willing to argue that point.

> You can run DOS for years, or memory diagnostics for years and never
> find a problem, yet your unix tries just the kind of access which
> fails.

Which is precisely why unix/Xenix is part of the standard test suite,
along with OS/2, Windows, and lots of other exotic stuff.

> [...] Your system seems not to run safely at its top speed, because
> the MMU sometimes does not give the memory chips enough time to
> respond.

That's a simple design flaw.  There's no excuse for it.

> (Our supplier has often been able to solve our problems by replacing
> the memory.  It REALLY works.)

Then your supplier has demonstrated that it is a design flaw.

I don't think the question is just related to too-slow RAM.  There may
be subtle design flaws in the various motherboard chipsets that don't
show up unless more than one DMA channel is running.  Perhaps it would
be a good thing to modify the memory test to run more than one DMA
channel while doing the RAM test.  I'll have to consult some engineers
on what the worst cases really are...

> Since memory is expensive they just put in slower chips than the
> machine really needs. I hope they are listening?????????

If you let the marketing/purchasing/finance people run wild, that
probably would happen.  But Systems Validation would never sign off to
it.  In our case (Dell), there is the additional threat of paying for
on-site service (and paying for the 800 line time).  There are ways to
cut corners without compromising reliability, but you'll hurt raw
performance - and you don't do things to hurt the prime selling point
for your machine.
-- 
James R. Van Artsdalen   ...!uunet!utastro!bigtex!james   "Live Free or Die"
Home: 512-346-2444 Work: 338-8789   10926 Jollyville Rd #901 Austin TX 78759