Path: utzoo!attcan!uunet!snorkelwacker!apple!marc
From: marc@Apple.COM (Mark Dawson)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Thoroughness of Mac Boottime Memory Test
Message-ID: <39035@apple.Apple.COM>
Date: 27 Feb 90 17:55:50 GMT
References: <9805@batcomputer.tn.cornell.edu>
Distribution: na
Organization: Apple Computer Inc, Cupertino, CA
Lines: 33

In article <9805@batcomputer.tn.cornell.edu> pottle@tcgould.tn.cornell.edu (Chris Pottle) writes:
>I recently purchased 4MB of SIMM memory. I installed 2MB in each of two
>practically identical Mac Pluses, both upgrades from 512Ks. Each Plus has
>a DataFrame hard disk (one with a much older driver than the other). One of
>the machines seems to work perfectly. The other crashes in several
>spectacular ways when applications are launched under Multifinder (Excel is
>an exception). I swapped the hard disks, expecting the problem to move
>with the disks. It didn't - the problem is with the machine. I understand
>applications load in different areas of memory under Multifinder than under
>Finder. 
>Question: How thorough is the memory test done at startup (both
>machines pass this test)? 
So-So.  The main problem is speed (of booting).  The diagnostics we ship to 
dealers take 40 seconds to a couple of minutes to test 8 megs of memory 
(depending on how many passes are run).  One 3rd-party program (I forgot the
name--sorry) took 8 hours to do a real thorough test (it did about 100 
different types of memory tests).

Our marketing people decided that 40+ seconds were too long to wait EACH time
you booted up (before you even got the system software to start booting).  Even
on a Mac+ system with 1mb, you may wait an extra 5 seconds or so (which was
deemed too much).

Generally, engineering has been slowly winning the testing battle with market-
ing, with the result that the new machines (like the IIci) have better RAM 
testing than older ones.

So your problem COULD be flaky RAM (make sure you've seated it correctly/snugly
since that is a major cause of problem RAM).

Hope this enlightens you somewhat.

  Mark