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From: wicklund@intellistor.com (Tom Wicklund)
Newsgroups: comp.emacs
Subject: Re: msdos GNU emacs?
Message-ID: <1991Feb19.215735.6843@intellistor.com>
Date: 19 Feb 91 21:57:35 GMT
References: <1991Feb19.025123.12089@agate.berkeley.edu>
Distribution: usa
Organization: Intellistor
Lines: 28

In <1991Feb19.025123.12089@agate.berkeley.edu> cotner@ronzoni.berkeley.edu (Carl F. Cotner) writes:

>I am wondering why there is no available msdos port of GNU emacs.  The obvious
>answer seems to be emacs' size.  If this is indeed the reason, how much memory
>would emacs need?  Considering that there is an Atari ST port which I assume is
>smaller than 1 meg, it would seem that one should be able to port it to msdos
>if you used a dos extender.  Has anyone done this?  It would sure be nice to
>have emacs at home.

I've looked a bit at the source to GNU emacs.  The primary problems I
see to an MSDOS port are:

1.  Emacs reads the full source file into memory and manipulates it
there.  This results in very large memory use.  Emacs on a UNIX system
can grab several megabytes during routine editing of relatively small
files.

2.  GNU emacs is not truely portable.  Rather it appears to be written
to run on 32 bit machines.  A 32 bit int is built into the code (or at
least, 32 bit minimum int size).

3.  The use of 24 bit pointers complicates MSDOS segment:offset
addressing.

A practical MSDOS port of GNU emacs would probably require replacing
the source file handling with a scheme which swaps text to disk along
with a similar ability to swap elisp code back to disk.  However, this
just handles the memory size issue, it doesn't deal with 32 bit ints.