From: "Luke Bishop" <lbishop AT calvin DOT stemnet DOT nf DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: .COM's with DJGPP?
Date: 18 Apr 1998 22:22:37 GMT
Organization: The Zone
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Message-ID: <01bd6a50$8a708600$3048a5c6@technoid>
References: <35379F0B DOT 6F79F86F AT indigo DOT ie> <3537F565 DOT 3C1CCCA2 AT a DOT crl DOT com> <3538D4C4 DOT 6919240 AT lr DOT net> <3538F4EF DOT A11E233D AT a DOT crl DOT com>
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To: djgpp AT delorie DOT com
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> > In fact, it will probably hang the machine when run!
> 
> It probably will not hang the machine when run!  Who knows about such
> details?  We may never find out.

Oh yes it will.  An EXE has a header, a COM does not.  The "MZ" in the
header for the magic number will crash the computer.

> 
> > DOS .com files are a special breed of executable that that must be
under
> > a certain size (I don't know what it is) and contains direct Intel
> > machine codes.  COM files can be written with either NASM (the Netwide
> > Assembler, available free at www.cryogen.com/nasm) or the DEBUG program
> > that comes with DOS.
>                        or vi, with the help of the Alt-Numbers keys.

If you really need COM, it basically must be 16-bit.  A COM file must be
under 64K bytes long, has a single segment, a small stack, etc.  They are
fairly useless for 32 bit protected mode.