Path: utzoo!mnetor!uunet!mcvax!cernvax!ethz!forty2!poole
From: poole@forty2.UUCP (Simon Poole)
Newsgroups: comp.sys.atari.st
Subject: Re: ST hardware scrolling
Message-ID: <237@forty2.UUCP>
Date: 26 Apr 88 21:28:37 GMT
References: <544@csvax.liv.ac.uk> <4484@batcomputer.tn.cornell.edu> <1794@brahma.cs.hw.ac.uk>
Reply-To: poole@forty2.UUCP (Simon Poole)
Organization: Exp. Physics University Zuerich
Lines: 30


My two cents:

        - Screen refresh rate is 50/60/70 Hz, even if you switch
          screens faster, nobody actually sees your work of art,
          so you can just as well scroll 2-3 lines at once in
          software and synchronize it with the VBI and get the
          same effect.

        - Doesn't work in 50 line mode on monochrome screens.

        - As soon as you start having portions of the screen which
          should stay static, your performance win gets smaller
          and smaller (in uEmacs or in a VT100 Emulator this would
          lead to added complexity that's just not worth the 
          trouble).

        - While hardware scrolling on the ST might be great to
          show off to your friends:
          "Hey look, it scrolls so fast that you can't read the
           text anymore!"
          it's not realy useful, typically 40 to 50 lines/second
          give a pleasing (and half legible) effect (Tempus does
          ~46 lines/second on normal text with full size window).


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UUCP:   ...mcvax!cernvax!forty2!poole			Simon Poole
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