Path: utzoo!attcan!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.binaries.ibm.pc.d
Subject: Re: Brown Bag Memory Test--worthless?
Message-ID: <12656@steinmetz.ge.com>
Date: 23 Nov 88 16:05:51 GMT
References: <301@bilver.UUCP> <512@mitisft.Convergent.COM>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 25

In article <512@mitisft.Convergent.COM> dold@mitisft.Convergent.COM (Clarence Dold) writes:

| On a separate thought:
| A Memory diagnostic that checks refresh will write a pattern to all of 
| memory, and then wait some arbitrary length of time (14 seconds), before
| reading.  It then waits another 14 seconds, and reads again.
| If refresh isn't working, or if a read causes a bit toggle due to bad
| parity circuits, this will catch it.
| 
| A memory test that only takes 5 seconds to run isn't testing a whole lot.

  The refresh rate on a PC or AT is settable from software. There are
programs which allow you to play with the value. Making it longer gives
fewer wait states (up to 3% CPU speedup!) and making it shorter may
allow you to run bad memory chips without getting parity errors.

  If I were writing another memory test program, I'd definitely check
the margins on the refresh, but I'm not sure that my program would stay
valid while running, so it would report refresh errors by crashing the
system.

-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me