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From: AWOODHULL@hamp.hampshire.edu (Al Woodhull)
Newsgroups: comp.virus
Subject: Re: Is there a 1024 virus? (PC)
Message-ID: <0005.9106181359.AA17901@ubu.cert.sei.cmu.edu>
Date: 17 Jun 91 17:03:00 GMT
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Approved: krvw@sei.cmu.edu

>  Can anyone suggest an explanation of our observation on several
>  computers (various IBM pc types) of a result from chkdsk of 654336
>  bytes of total memory?

On one of the computers I use I have determined that the ROM BIOS
reserves 1 K at the top of RAM memory. I first discovered this while
teaching my assembly language students about memory allocation, in
preparation for an assignment to implement some of the ideas in
Padgett's Six Bytes paper, and I was a little startled to think that a
virus might have been present in my own system for an unknown period
of time while I was playing local expert.

I verified that it was the ROM by booting from floppies with different
DOS versions that worked OK on other systems.

I don't know the purpose of this memory reservation, when I look at it
with DEBUG it seems to have been initialized to all zeros, but a few
bytes scattered throughout have other values.

The ROM in this machine is identified as DTK Corp.  COMPUTER XT,
DTK/ERSO/BIOS 2.29 (C) 1986.

 -- Al    awoodhull@hampvms.bitnet