Path: utzoo!attcan!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.sys.ibm.pc.programmer
Subject: Re: NULL pointer error
Keywords: Null dos error
Message-ID: <319@taumet.com>
Date: 15 Jul 90 17:20:25 GMT
References: <2008@bnlux0.bnl.gov> <27092@netnews.upenn.edu>
Organization: Taumetric Corporation, San Diego
Lines: 14

weisen@eniac.seas.upenn.edu (Neil Weisenfeld) writes:
>If the program is attempting to write to a NULL pointer, you could
>try watching address 0x0000:0x0000 as this is where the "NULL" pointer
>points.

Sadly, it's not this simple.  The NULL pointer error is reported for
a range about about 128 bytes starting at data address zero.  In a small
data model program, this is not 0x0000:0x0000, but addresses DS:0x0000 -
DS:0x007F.  I don't believe this error can be reliably reported for
other-model programs, since there is no place to put the checksummed data
for comparison at program exit.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com