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Path: utzoo!mnetor!seismo!ut-sally!ut-ngp!werner
From: werner@ut-ngp.UUCP (Werner Uhrig)
Newsgroups: net.micro.68k,net.micro.mac,net.micro.amiga
Subject: memory test with the 68000 (The Worm Memory Test)
Message-ID: <3867@ut-ngp.UUCP>
Date: Sat, 23-Aug-86 18:03:30 EDT
Article-I.D.: ut-ngp.3867
Posted: Sat Aug 23 18:03:30 1986
Date-Received: Sat, 23-Aug-86 22:01:00 EDT
Organization: UTexas Computation Center, Austin, Texas
Lines: 33
Keywords: 68000 memory test assembly program self-overlaying
Summary: A self-overlaying test to help diagnose memory errors
Xref: mnetor net.micro.68k:1156 net.micro.mac:6736 net.micro.amiga:4373

I just received Dr Dobbs Journal (DDJ) .. September 1986, and a recent
discussion in net.micro.mac of reliability-questions when using a Mac in
critical applications (due the fact of the lack of parity-bits in memory)
came to mind, when I read the title of an article on page 112:

Memory test with the 68000 - THE RIGHT TO ASSEMBLE: The Worm Memory Test
(by Jan W. Steinman). which includes the code ready to run on a Tektronix 4404,
with only 2 system dependent instruction [claim of the author, not mine]
he seems to have used it on the Amiga, also, but no mention of the MAC is
made [I only scanned the article, though].  to quote a few lines:

       "The test uses a dynamically executing program as the actual test data
	Unlike previous programs of this type, however, this worm has a special
	twist - it is able to overlay itself while it is executing thanks to
	the MC68000's pre-fetch register. ....

	... I originally developed the MC68000 Worm test for an embedded
	processor application that was having dynamic RAM refresh problems.
	It was discovered that conventional RAM tests, which move smoothly
	up through consecutive addresses, were masking the problem by
	unintentionally providing software refresh.  The test is not long
	enough to cause a complete cycle of all a dynamic RAM's row-address
	strobe (RAS) lines and was able to help diagnose the problems."

I doubt that I'll get to do anything more to try to install this on the MAC,
but I'm sure (well, hope) someone out there is tempted.

I know, DDJ makes their code available online somewhere, but I can't find the
number anywhere in the magazine (or my phone-files on the computer for that
matter) but I found a sales pitch in the magazine for their code on floppies;
$15 - call (800)528-6050 ext.4001

	Cheers,		---Werner