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Path: utzoo!mnetor!seismo!rutgers!princeton!allegra!alice!ark
From: ark@alice.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: large file text editor
Message-ID: <6813@alice.UUCP>
Date: Mon, 20-Apr-87 09:09:31 EST
Article-I.D.: alice.6813
Posted: Mon Apr 20 09:09:31 1987
Date-Received: Tue, 21-Apr-87 03:00:48 EST
References: <119200008@convexs> <116@amcad.UUCP> <280@cup.portal.com> <1044@super.upenn.edu.upenn.edu>
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 51
Keywords: MS-DOS, editors
Summary: DVED

The fastest MS-DOS editor I've ever seen is DVED, from Robert Dewar.

It is of somewhat unusual design, as it is really a sequential editor
that tries very hard to hide the fact.

In other words, there is an input file and an output file.  Lines
from the input file flow into the bottom of the screen; lines from the top
flow into the output file.  You can change anything on the screen.

If you ask it to edit a single file, it puts the output in a temporary.
On exit it renames the input file to the form *.BAK and renames the
output file to replace the input file.

If you try to back off the top of the screen, lines pushed off the
bottom go into a temporary file.  This file, if non-empty, is read
in preference to the input file when taking new lines into the screen.

This behavior has several interesting consequences:

	The size of a file is never limited by memory capacity.

	If you never back up more than a screenful, the editor
	doesn't use any more disk space than needed to contain
	the two copies of your file you'll want to keep anyway.

	If you do back up, it still doesn't use more disk space
	than it absolutely needs.

	If you jump from here to there in a file, you get there
	by traversing all the intervening text.

This last characteristic might seem annoying, and indeed it would
be if the editor weren't so incredibly fast.  On a 4.77 mHz 8088,
it manages about five screens a second (!).  It's even faster on
faster machines.  Thus it is entirely comfortable to edit files with
thousands of lines.

Another interesting thing about DVED is its price -- it's free.
Dewar wants people to re-distribute it (but not sell it) because
it contains advertising for some of his other products.  The
advertising is completely unobtrusive -- you only see it if you
ask for it explicitly in the help menu.

The one disadvantage of DVED I have found it that it is WYSIYG
(what you see is what you get) with a vengeance -- it won't let
you produce a line that's too long to fit on the screen, period.
In fact if you edit a file with lines longer than that, it will
quietly truncate them.  This deficiency is remedied in the version
that he sells (for a pretty nominal price).

Further information on request.