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Article #1031

Re: .com and .exe files

#1031
From: Michael R Castle
Date: Wed, 27 Jan 1993 11:43
26 lines
1955 bytes
In article <C1HtvM.Eun@world.std.com> mikep@world.std.com (Michael Podanoffsky) writes:
>
>Both .com and .exe files can be loaded anywhere.
>
>A .com file contains no segments whatsoever.  All data, code and stack share
>the same 64k segment.
>
>An .exe file contains segments and can exceed 64k.  Only .exe files are really
>rommable should this ever be needed.  One major side effect is that different
>code segments may be produced.
>
>.com files are an exact byte image of the program in memory without any
>relocation information.  That means all references are near.

Question:  Can't com files use more than 64k?  Once the program is going,
you can pretty much do what ever you want with the segment registers, and
request more memory, and access the full 640 k.  I seem to remember a while
back that someone wrote a program (forth interpreter, if I remember 
correctly) that is a .com file, but isn't limited by 64k.

mrc
-- 
Mike Castle .-=NEXUS=-.  Life is like a clock:  You can work constantly
  mcastle@cs.umr.edu     and be right all the time, or not work at all
S087891@UMRVMA.UMR.EDU   and be right at least twice a day.  -- mrc
    We are all of us living in the shadow of Manhattan.  -- Watchmen
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References: <1993Jan25.231026.6514@news.unomaha.edu> <1993Jan26.201921.21687@ousrvr.oulu.fi> <C1HtvM.Eun@world.std.com>

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From: mcastle@cs.umr.edu (Michael R Castle)
Subject: Re: .com and .exe files
References: <1993Jan25.231026.6514@news.unomaha.edu> <1993Jan26.201921.21687@ousrvr.oulu.fi> <C1HtvM.Eun@world.std.com>
Date: Wed, 27 Jan 1993 11:43:20 GMT
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