Path: utzoo!attcan!telly!lethe!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!ames!claris!outpost.UUCP!peirce
From: peirce@outpost.UUCP (Michael Peirce)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Memory speeds can be critical (was: SIMMs for IIsi - what do I need?)
Message-ID: <0B010004.6agfm9@outpost.UUCP>
Date: 21 Dec 90 17:51:40 GMT
Reply-To: peirce@outpost.UUCP
Organization: Peirce Software
Lines: 26
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In article <NCrwEGxa@visix.com>, amanda@visix.com (Amanda Walker) writes:
 We're not talking putting bipolar SIMMs (an amusing concept) into a IIsi.
> We're talking about putting in SIMMs that fall into different spots in
> the "safe zone."  If the problem really was speed slew of some sort,
> you'd have to have actual matched sets of SIMMs, not just ones all stamped
> with the same speed.  A 100ns SIMM may well be an 80ns SIMM that got marked
> as 100ns because the memory company had more orders for 100ns SIMMs that
> month.  The rating is simply the worst case--the best case is always
> undefined.

This is exactly how they do it.  Each production line has a big
test machine at the end.  They sort the chips into various bins
based on their conclusion that this chip will have its outputs settle
in 80ns or 100ns.  Many many times they will label all the chips that
tested at a faster speed with the lower speed just because of the
orders coming in that week.  Many chips labeled 100ns are in fact
the very same chips that tested as 80ns and could have been labeled
as such.

-- michael, (very) formerly of Fairchild Test Systems


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