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From: Greg@AppleLink.apple.com (Greg Marriott)
Newsgroups: comp.sys.mac.misc,comp.sys.mac.programmer
Subject: Re: MEMORY FAULTS - any way to check ram for intermittent faults??
Message-ID: <10242@goofy.Apple.COM>
Date: 14 Sep 90 18:53:37 GMT
Sender: usenet@Apple.COM
Distribution: comp
Organization: Apple Computer, Inc.
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References:<1990Sep11.174118.12194@Neon.Stanford.EDU> <615@keele.keele.ac.uk> <1990Sep12.185459.15694@ux1.cso.uiuc.edu> <1990Sep13.154744.2277@midway.uchicago.edu>

In article <1990Sep13.154744.2277@midway.uchicago.edu> 
dwal@ellis.uchicago.edu (David Walton) writes:
> >Try saying "sm 2 0101", continuing (what's the command for that in the
> >mini-monitor?) and running the program.  If my guesses are correct, it 
will
> >fail every time.
> 
> Um...I think that's a typo.  You mean sm _0_ 0101, don't you?  You
> don't want to put this at memory location 2, you want it at 0.
> 
> The proper sequence is
> 
>         >sm 0 0101 (or any odd four-byte number)
>         >g

In this case, sm 2 0101 is correct.   0101 is an odd TWO byte number, 
being stored in the low word of the longword at 0.

If you want to find programs dereferencing location 0, a good value to put 
there is $00f0f0f1.  This will cause an adddress error on 68000 macs, and 
a bus error on others.  There is an INIT called Mr. BusError that writes 
this value at location 0, and keeps writing it there from time to time (in 
a VBL task, I think).  It keeps writing the value there in case an errant 
program writes to location 0, blasting the bus error causing value.

Greg Marriott
Just Some Guy
Apple Computer, Inc.