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From: ian@sibyl.eleceng.ua.OZ (Ian Dall)
Newsgroups: comp.arch
Subject: Re: Tradeoffs
Message-ID: <671@sibyl.eleceng.ua.OZ>
Date: 7 Jun 90 05:39:16 GMT
References: <640@sibyl.eleceng.ua.OZ> <2662CE6C.3E68@tct.uucp> <26798@eerie.acsu.Buffalo.EDU> <266576A7.6D17@tct.uucp> <9494@pt.cs.cmu.edu> <1990Jun3.041822.13548@utzoo.uucp> <27416@eerie.acsu.Buffalo.EDU> <.5X3-ZB@xds13.ferranti.com>
Reply-To: ian@sibyl.OZ (Ian Dall)
Organization: Engineering, Uni of Adelaide, Australia
Lines: 40

In article <.5X3-ZB@xds13.ferranti.com> peter@ficc.ferranti.com (Peter da Silva) writes:
>In article <27416@eerie.acsu.Buffalo.EDU> pjg@acsu.Buffalo.EDU (Paul Graham) writes:
>> now i'd like to ask what would gnu emacs look like if henry wrote it
>> but he probably wouldn't; so a question.  has someone written something
>> comparable to gnu emacs that is significantly smaller?
>
>There are several full-featured fully programmable (as in... they include
>a programming language at least as capable as Gnu-lisp) editors that run
>in well under the full 640K available in an IBM-PC. Just what does GNU Emacs
>provide over things like Jove other than that?

Dunno much about Jove. One feature of GNU emacs which not many of its
competitors offer is online documentation. I've no doubt that GNU
emacs would be a *bit* smaller if totally rewritten instead of having
grown over such a long period. In a running emacs it is easier to get
a process size of over 2MB. Most of this is due to the number of files
visited. In some ways, emacs method of reading in all of every file
visited seems wasteful, but in practice it is not too bad. One
alternative is to make (allow) the user two only read in "pages" of a
file at a time. That is certainly workable, but is not transparent.
Another alternative is to automatically read in sections of files as
necessary and, if necessary, write out data to temporary files.
Surprise, surprise, that is almost exactly what a virtual memory
operating system does. So why not *let* the virtual memory operating
system do it? (*) Why does it matter that "ps" shows a large number for
the process size?

The code for emacs (including pre loaded lisp) is around 600K. This
doesn't seem so bad if you stop thinking of it as a text editor, and
start thinking of it as a language interpreter which runs an editor
among other things.  A quick check shows that there is an editor for C
programs written in elisp which weighs in at 12.5k (byte compiled).
Seems pretty lean and mean to me! How about a compare program in 659
bytes of elisp?

* This is the architecture relevant bit of the posting in case you
  were wondering!
-- 
Ian Dall     life (n). A sexually transmitted disease which afflicts
                       some people more severely than others.