Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!uwvax!oddjob!gargoyle!ihnp4!ihwpt!knudsen
From: knudsen@ihwpt.ATT.COM (mike knudsen)
Newsgroups: comp.sys.m6809
Subject: Editors and memory
Message-ID: <1687@ihwpt.ATT.COM>
Date: Tue, 19-May-87 14:13:27 EDT
Article-I.D.: ihwpt.1687
Posted: Tue May 19 14:13:27 1987
Date-Received: Sat, 23-May-87 02:38:25 EDT
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 34
Keywords: Text bigger than memory

There is already one OS9 screen editor, Dynastar from Frank Hogg,
that edits files too big for available memory.  Unfortunately,
its "window" can be advanced only forward thru the file--
if you need to go back and add a variable declaration
at the beginning, you must close the file and start over to
get the front part.  (Those of you with strong stomachs may
recall that the EDIT supplied with Coco Level 1 also handles
too-large files in this way.)

A good trick for Level 2 would be to put the entire file in
RAM, but not map all the blocks of it into the 64K space
at once.  A 512K machine could edit a whole 360K disk-sized file!
The user would see no delays when skipping around in the file
since there is no disk access involved.  The extra programming
needed in the editor (block-swapping algorithms) would not
be all that complex, it seems to me.

Trouble is, I'm not sure how OS9 could be cajoled into doing
this.  "Data modules" would be ideal, if you can find a friend
of a friend of someone who claims to have actually used one of
these elusive beasts (I've posted this challenge before, no
takers).  Maybe the editor could split up the text into 8K-delta
chunks, append OS9 program headers and CRCs to the chunks,
and get them LOADed that way.  Then the editor LINKs to the
ones currently chosen to be in its space.  Algorithms know to
skip over 'delta' bytes between blocks of text.
	mike k
PS:  Jim (was it you?), how do you run a QT out of 512K RAM when
it doesn't even have windows and graphics?  I haven't blown out
my Coco yet (but I will sooner or later, right?)
-- 
Mike J Knudsen    ...ihnp4!ihwpt!knudsen  Bell Labs(AT&T)
    Delphi: RAGTIMER    CIS: <memory failure, too many digits>
		"Just say NO to MS-DOS!"