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Path: utzoo!mnetor!yetti!mike
From: mike@yetti.UUCP (Mike Clarkson )
Newsgroups: comp.emacs
Subject: Re: flow control by termcap
Message-ID: <493@yetti.UUCP>
Date: Tue, 7-Jul-87 02:59:47 EDT
Article-I.D.: yetti.493
Posted: Tue Jul  7 02:59:47 1987
Date-Received: Thu, 9-Jul-87 00:37:26 EDT
Reply-To: mike@yetti.UUCP (Mike Clarkson )
Organization: York University Computer Science
Lines: 58

In article <492@yetti.UUCP> oz@yetti.UUCP (Ozan Yigit) writes:

    In article <491@yetti.UUCP> mike@yetti.UUCP (Mike Clarkson ) writes:
    >     
    >Take for example the much maligned, and ever present vt100.  In
    >the current Emacs distribution, the scroll region capabilities (sr: sf:)
    >are disabled.  Does this mean that in all of these years someone hasn't
    >figured out a way of making vt100's use scroll regions?  
    >You've got to admit that it *is* an important functional requirement 
    >for an Emacs.
    >     
    	For a *proper* implementation of Scroll regions along with
    	the true Goslings Dynamic Programming Algorithm for optimal
    	screen updates, see MicroEmacs (V30 / vt100) or 
    	MicroGnuEmacs (Termcap). It works very well indeed.

You missed the point entirely.  It's not the GNU Emacs algorithm that's
faulty, it's the termcap distributed with GNU Emacs that has the scroll
regions disabled.  I'm quite confident in RMS' ability to implement a
*proper* algorithm for screen updates.

In article <8707061437.AA06719@ucbvax.Berkeley.EDU> John Robinson writes:

    >> Does anyone have a good termcap entry for a vt100
    >> in Smooth Scroll mode?
    
    You have to be kidding.  If it could, emacs should take the vt100 out
    of smooth-scroll.  Certianly the fastest update will generally be to
    repaint the entire screen than to wait for the scroll to happen.
    Since emacs finds the fastest update, an accurate termcap would appear
    to be broken because you would never see the scroll happen.  So you
    would have to remove all forms of screen update, including
    clear-screen, and force it to use scrolling regions.  But then it
    will doubtless decide your terminal is too dumb to run emacs.  It
    would probably be right.
    
Maybe at 9600 baud, but it's not true at slow speeds.  If you are
yanking 3 or 4 lines at 1200 baud, scroll regions are indeed much faster.
Moreover, the main reason for having a smooth scroll at low speeds is
that it is much easier on the eyes than jump scroll.  I work a lot with
Gnu on a vt100 at 1200/2400 baud, and jump-mode plus no-scroll-region is
horrible.  Emacs will find the fastest way to update the screen *only* 
if it has an accurate termcap, and I would rather have Emacs figure it out
than accept your certainty that the fastest way to update will be
to repaint the entire screen.  So my question remains - does anyone 
have a good vt100 entry for smooth scroll mode?

-- 
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