Path: utzoo!attcan!telly!lethe!torsqnt!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: attcan!utzoo!henry@uunet.uu.net
Newsgroups: comp.sys.sun
Subject: Re: Summary: Adding memory to 3/60 3/80
Keywords: Miscellaneous
Message-ID: <1556@brazos.Rice.edu>
Date: 21 Sep 89 04:29:54 GMT
Sender: root@rice.edu
Organization: Sun-Spots
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X-Sun-Spots-Digest: Volume 8, Issue 126, message 5 of 15

>Our 3/80's arrived with 100ns. For testing purposes we put some of this
>memory in our 3/60, which arrived with 70ns. Everything worked fine, and
>still do.

Beware:  what you may have is a machine that is working fine with
practically zero margin for error.  Temperature changes or component aging
may push it over the edge, at which point it will develop non-reproducible
intermittent problems (ugh).  It is often the case that a particular
machine at a given time has more margin than it needs, since manufacturers
must design for worst cases.  So it's often possible to cut that margin
down without obvious ill effects.  The trouble is, unless you understand
the design, you don't know just how close to the edge you are.

There is also the possibility, of course, that Sun used 70ns memory in a
machine designed for 100ns because they were temporarily out of 100ns
parts...

                                     Henry Spencer at U of Toronto Zoology
                                 uunet!attcan!utzoo!henry henry@zoo.toronto.edu