Article View: comp.sys.atari.st
Article #32039Re: ST hardware scrolling
From: braner
Date: Wed, 20 Apr 1988 16:06
Date: Wed, 20 Apr 1988 16:06
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1531 bytes
[] Two problems with the suggestion for "hardware scrolling": (1) The ST's video pointer must be on a 512-byte boundary, NOT 256. Thus, incrementing it by $500 (1280) (to scroll by one text line) is NOT feasible. (I tried it: the screen goes crazy!) One could scroll TWO text lines at a time, though. (2) This solution only applies to scrolling the entire screen, while Tempus, Laser C, etc fast-scroll arbitrary WINDOWS. Rather impressive. What I do in MORE.TTP for fast scrolling is: no scrolling. I clear the screen before writing the next one. That is a lot faster since, again, 32000 bytes need to be manipulated (cleared, in this case) only once per 25 lines. It is also faster in another sense: The user can glance at the top lines while the bottom ones are being printed. In MORE (and GNOME too!), if you see that you want to scroll further, you press the appropriate key and the printing of the current screen is aborted immediately, the screen is cleared, and the next screen is printed. - Moshe Braner
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arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!think!bloom-beacon!mit-eddie!uw-beaver!cornell!batcomputer!branerReferences:
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!think!bloom-beacon!mit-eddie!uw-beaver!cornell!batcomputer!braner From: braner@batcomputer.tn.cornell.edu (braner) Newsgroups: comp.sys.atari.st Subject: Re: ST hardware scrolling Message-ID: <4484@batcomputer.tn.cornell.edu> Date: 20 Apr 88 16:06:35 GMT References: <544@csvax.liv.ac.uk> Reply-To: braner@tcgould.tn.cornell.edu (braner) Organization: Cornell Theory Center, Cornell University, Ithaca NY Lines: 24 Summary: yes and no