Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!hal!ncoast!allbery
From: allbery@NCoast.ORG (Brandon S. Allbery)
Newsgroups: comp.sys.mac
Subject: Re: Nix on mixing memory speeds?
Message-ID: <1989Sep24.160940.925@NCoast.ORG>
Date: 24 Sep 89 16:09:40 GMT
References: <11979@cit-vax.Caltech.Edu> <4002@phri.UUCP> <2040@leah.Albany.Edu> <1989Sep23.010904.7650@NCoast.ORG> <4007@phri.UUCP>
Reply-To: allbery@ncoast.ORG (Brandon S. Allbery)
Followup-To: comp.sys.mac
Distribution: usa
Organization: North Coast Public Access UN*X, Cleveland, OH
Lines: 29

As quoted from <4007@phri.UUCP> by roy@phri.UUCP (Roy Smith):
+---------------
| In <1989Sep23.010904.7650@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery):
| > He [i.e. me] was insulting only to the person who claimed to the original
| > poster that the memory speeds *had* to match. [...] There is, by and large,
| > only *one* case where the memory speeds would have to match: if the memory
| > storage system accesses more than one memory chip at the same time, all of
| > those chips must be the same speed or the memory access hardware will get a
| > severe case of heartburn.
| 
| 	Again, bullshit.  OK folks, let's go over this slowly.  When a RAM
+---------------

All I can offer in extenuation is that this *was* the case at the time when I
got my knowledge.  However -- the computer in question had memory-management
hardware that was consistently riding the very edge of the capabilities of the
chips involved, including memory and address-translation circuits, etc., and
in fact one memory chip that was "in spec" caused the memory management
hardware to do weird things.  The chip was then tested in another computer and
it worked fine; and its replacement in the first computer also worked fine.

Perhaps the moral for all should be "don't take computer hardware for granted."

++Brandon
-- 
Brandon S. Allbery, moderator of comp.sources.misc	     allbery@NCoast.ORG
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