I don't know the exact details, but I think one test writes all 1s and
reads them back, one writes all 0s and reads them back, and one writes (and
reads back) some alternating pattern.  A memory location that has died might
be stuck as 0 or 1; a location that is flaky might simply imitate its
neighbors.  No single pass test could check for all of these conditions.

David Gillett


On 14 Oct 2003 at 20:06, Mandar Naik wrote:

> Thanks David, what I wanted to know was whether it was usual for the memory
> test to run thrice...could you tell me what are the three tests?
>
> Regards,
> Mandar Naik
>
> ----- Original Message -----
> From: "David Gillett" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, October 14, 2003 2:22 AM
> Subject: Re: [PCBUILD] Memory errors?
>
>
> > 1.  The wording is not very obvious, but when you "disable the Quick Power
> > ON Self Test", that instructs the BIOS to perform the full/slow power-on
> > self-test.
> >   The quick power-on self-test will run the memory counter from 0 to the
> > amount of memory present, ONCE, and will not even really test the memory
> as
> > it goes.  The full/slow test runs the counter from 0 to total about three
> > times, once for each of the different kinds of tests it performs.
> >   A common recommendation is to enable the quick test, and allow software
> > that is part of the OS to test the memory instead.  For Windows 95/98/ME,
> > HIMEM.SYS is the usual tool for this, launched from CONFIG.SYS.
> >
> > 2.  If you really have 128MB of working memory installed, the counters
> > should go up to 131036K.  If they're stopping at 76MB, but not reporting a
> > memory error, then it sounds like not all of your installed memory is
> being
> > recognized by the motherboard.  This might be an additional problem.
> >
> > David Gillett
> >
> >
>
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