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Date:      Sat, 22 Jun 1996 17:38:28 -0500 (CDT)
From:      Alex Nash <alex@zen.nash.org>
To:        michaelv@HeadCandy.com
Cc:        freebsd-hardware@freebsd.org
Subject:   Re: Mixing SIMMs of different speeds
Message-ID:  <199606222238.RAA22378@zen.nash.org>

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> >Aren't both banks (1&2) accessed simultaneously for any 32-bit access?
> >When you said all slots, you mean groups of two, right?
> 
> I was going under the assumption that one "bank" consists of the
> smallest usable memory size, i. e. two 72-pin SIMMs.  So, bank 1 is
> the first pair of SIMMs, bank 2 the second....

Sorry, I got my terminology backwards :)

> >> If it were going to work at all, that would be my suggestion: put the
> >> slower memory first, so if it does some sort of test to see how fast
> >> your memory is, it might use the slower memory for the timings.  Note
> >> that this is highly speculative and implementation specific.  Only the
> >> people who designed your motherboard can tell you for sure.
> 
> >Good, so I'm not crazy for thinking this might work :)

> Right -- this is what I would expect.  But there's still no guarantee.
> Some engineer may have found it more useful to test, say, the last
> SIMM installed.  How can we know without asking him?

I accept that there's no guarantee, but knowing programmers, the extra
effort required to figure out which is the last bank would probably be
passed up in favor of a hard coded get_ram_speed(0) :)

Alex



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