Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!ncar!tank!uwvax!astroatc!nicmad!brown
From: brown@nicmad.UUCP (Vidiot (Vid-e-it))
Newsgroups: comp.sys.ibm.pc
Subject: Re: EXE And COM files
Message-ID: <3543@nicmad.UUCP>
Date: 15 Dec 88 02:29:59 GMT
References: <596@nikhefh.hep.nl>
Reply-To: brown@nicmad.UUCP (Vidiot (Vid-e-it))
Organization: Vidiot's Hangout
Lines: 26

In article <596@nikhefh.hep.nl> i14@nikhefh.hep.nl (Martin Los) writes:
<Could anyone help me with these problems?
<1)What is the general format of an EXE file?

These are re-locatable programs.  The code is NOT directly executable.  If
you use the DOS debug command, it will LOOK like it is, because the debug
program does the relocating when it sees that it is a .EXE program.  To look
at the code BEFORE relocation takes place, rename the program and then look
at it with DEBUG (the only way to modify .EXE files).

<2)What is the general format of a COM file?

These are direct machine language programs that must fit within a 64K page
area.  That is why they are never longer than 64K.  These can be looked at
directly with debug, executed and changed within debug.

<3)Is it possible to add a portion of ML(machine language)code to an EXE or
< COM file??

.COM files can be easily modified with debug (or other tools), but .EXE files
are tough.  Don't get me wrong, they can be modified.  But because they are
re-locatable, you must really know what you are doing.
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