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Path: utzoo!decvax!decwrl!pyramid!micropro!well!ljz
From: ljz@well.UUCP
Newsgroups: net.micro.pc
Subject: Re: Query: can MS C generate .COM files?
Message-ID: <1045@well.UUCP>
Date: Wed, 7-May-86 21:07:48 EDT
Article-I.D.: well.1045
Posted: Wed May  7 21:07:48 1986
Date-Received: Thu, 8-May-86 23:42:48 EDT
References: <2479@pogo.UUCP>
Reply-To: ljz@well.UUCP (Lloyd Zusman)
Distribution: na
Organization: Whole Earth Lectronic Link, Sausalito CA
Lines: 37
Keywords: C, .COM, Query

In article <2479@pogo.UUCP> maybee@pogo.UUCP (Joe Maybee) writes:
>It is possible, using MS C, to generate an .EXE
>file that can be converted to a .COM file?
>
>If so, could you tell me how it's done?
>
>If you KNOW it to be impossible, would you please
>explain why?

You can do it, but the easiest way is also expensive.  In the library
is a startup routine that sets up a stack, defines certain globals,
etc., etc.  This routine then passes control to your main() routine.
Microsoft's startup routine is meant for .EXE files, which means that
there's a STACK segment and some other things that make it impossible
to generate a .COM file.

Microsoft will *sell* you the source code to this module for $500.00 (!!)
if you want to modify it so that you can create a .COM file.  This is
another example of what, in my opinion, is a user-hostile attitude on
the part of Microsoft.  Lattice C and others not only *give* you the
source to this startup module, but will give you the source to an
alternate startup module expressly for producing .COM files.

You could write your own startup module and link it in ahead of Microsoft's
library.  It would need an 'ORG 100h' statement and no segment labeled
'STACK' ... that's all (I think) you need to ensure that EXE2BIN can
convert the .EXE to a .COM.  That part's fairly easy.  The hard part is
figuring out exactly what Microsoft does in its startup module and
duplicating that (otherwise, you couldn't get the command line args,
the stream-oriented file stuff wouldn't work right, etc.).  Given
Microsoft's "we-don't-give-a-damn" attitude for people who buy less
than 100 copies of its software at a time, I fear you will have a
difficult time getting the info from them.

Sorry to give you such bad news.  If anyone has been able to get more
satisfaction from Microsoft on this than I have, then I'd love to
see a posting of how to do this .COM file thing.