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From: geoff@burl.UUCP
Newsgroups: comp.sys.apple
Subject: Flashing screen in 80 column mode (on unenhanced IIe)
Message-ID: <2568@burl.ATT.COM>
Date: Thu, 11-Jun-87 09:53:47 EDT
Article-I.D.: burl.2568
Posted: Thu Jun 11 09:53:47 1987
Date-Received: Sat, 13-Jun-87 09:31:14 EDT
Reply-To: geoff@burl.UUCP (geoff)
Distribution: comp.sys.apple
Organization: AT&T Technologies, Burlington, NC
Lines: 30

/* I don't know what happened the first time.  Oops! */

This is undoubtedly an old question, but one I don't know the answer
to.  I store directly to the display pages for added speed.  When I
am in 40 column mode, everything is fine.  When in 80 column mode
everything works ok, but the screen sometimes 'flashes' (with inverse
'@' signs -- NULL, I think) while I am typing (and echoing my input
to the screen).  I assume this is because I am trying to access 
the memory or swapping MAIN and AUX pages at the same time as the
display generator is reading or some such.  Is there a byte somewhere
that I can test to see if it is safe to store or flip (or whatever I
am doing to cause this flash)?   Oh, yeah, I am using the alternate
character set and am strictly displaying text.

One other question.  I have read that it is not save to use the soft
switches (like I am doing above) because these are not in the same
postion on clones like the Franklin or Laser, or even different 80-col
cards.  The only ones I use are for the alternate character set (gotta
have a full set of inverse -- although the mousetext on a IIc was annoying
to program around), STORE80, PAGE1, and PAGE2.  In other words, the ones
I need to store text to the screen.  Does anyone have any hard info on
this?  I can go back to the Apple routines, I guess, but the speed is
hard to beat.

	thanks a lot,
-- 

		geoff sherwood
		...![ ihnp4 ulysses cbosgd mgnetp ]!burl!geoff
		...![ ihnp4 cbosgd akgua masscomp ]!clyde!geoff