Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!comp.vuw.ac.nz!virtue!canterbury.ac.nz!phys169
From: phys169@canterbury.ac.nz
Newsgroups: comp.terminals
Subject: Re: screen clears in emphasize mode
Message-ID: <1990Sep7.170809.9118@canterbury.ac.nz>
Date: 7 Sep 90 07:53:56 GMT
References: <1990Aug28.152155.157@midway.uchicago.edu> <1990Aug30.024402.6206@icc.com>
Organization: University of Canterbury
Lines: 23

In article <1990Aug28.152155.157@midway.uchicago.edu> goer@quads.uchicago.edu (Richard L. Goerwitz) writes:
>Let's say I send the command for reverse video mode, and then
>the sequence for a screen clear.  Is it typical for terminals
>to clear the screen to normal-mode spaces or reverse video spa-
>ces?  The reason I ask is that, for terminals which permit it,
>the so+cl approach is the quickest and most reliable to cover
>the screen in reverse video.
> 
It is common to clear the reverse video attribute when clearing the screen,
certainly in the older style VDU's where the reverse attribute takes up a
character position on the screen (most Televideo, ADM, etc screens). Even on
screens where there is a hidden bit for reverse video (e.g ANSI, DG) the clear
screen often resets the mode at the same time. PC's are the exception.

Many screens have a simple method of setting reverse video on the screen as a
whole, e.g. the ANSI sequence: ESC [ ? 5 h (on VT200-compatibles, at least).
It is ESC b on most Televideo terminals and ESC ^ 1 on a WY99 in native mode.
In this mode, any reverse video commands received toggle the individual
characters back to normal mode.  Note that the ESCAPE b sequence doesn't clear
the screen, so you can send ESC b and ESC d alternately to flash the whole
screen!

Mark Aitchison, Physics, University of Canterbury, New Zealand.