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Date:      Fri, 14 Apr 1995 18:47:16 -0700 (PDT)
From:      "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com>
To:        phk@ref.tfs.com (Poul-Henning Kamp)
Cc:        cmf@ins.infonet.net, current@FreeBSD.org
Subject:   Re: Interesting (and odd) effect in -current
Message-ID:  <199504150147.SAA02234@gndrsh.aac.dev.com>
In-Reply-To: <199504150128.SAA18903@ref.tfs.com> from "Poul-Henning Kamp" at Apr 14, 95 06:28:22 pm

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> 
> > Humm... I just came up with a fast and dirty way to find out if we are
> > ever reading memory we have not written into (should never ever occur,
> > right, as that would be using unitialized data).  If it wasn't so chip
> > set specific, you could actually turn parity off, use the special ports
> > to write bad parity in all of memory.  Then let things fly.
> > 
> > But I have digressed, if the BIOS didn't manage to get this write at
> > power on, you would get NMI interrupts no matter what OS you ran.  I
> > don't see a reason to add code to FreeBSD that really belongs in the
> > BIOS in the off chance that some really rare broken motherboard could
> > then work.
> I belive himem.sys clears memory to aviod that problem...

MicroSloth put a quick pass memory test in himem.sys at DOS version
6.0 to reduce the number of tech support calls they got due to NMI's
while DOS and/or Windows was running.  Now they can report it when
himem.sys loads as ``Please check your memory, it has failed the memory
test''.  Most DOS folks don't know what NMI means, and thus it caused
tons of support calls to Microsoft from people who thought it was
coming from the application or the OS :-).

MicroSloth's test is no better than what David wrote and put in
FreeBSD.



-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                   Custom computers for FreeBSD



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