🚀 go-pugleaf

In article <4484@batcomputer.tn.cornell.edu> braner@tcgould.tn.cornell.edu
(braner) writes:
>(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.

No. It can go on a 256 byte boundary. I tried, and suceeded long ago for some
smooth scrolling I did and it worked just fine for me. The screen just looks
crazy because 256 bytes doesn't use an integer number of scanlines.
(1.6 in colour modes)

>(2)  This solution only applies to scrolling the entire screen,
>while Tempus, Laser C, etc fast-scroll arbitrary WINDOWS.  Rather
>impressive.

Yup! I have not seen Tempus but my guess is they use "movem.l" all over the
place and possibly force the windows to lie on 8 or 16 pixel boundaries so that
there is no half characters to slow the thing down.

It is often the case that a little machine (not OS) dependance goes a long way.

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 Neil Forsyth                           JANET:  neil@uk.ac.hw.cs
 Dept. of Computer Science              ARPA:   neil@cs.hw.ac.uk
 Heriot-Watt University                 UUCP:   ..!ukc!cs.hw.ac.uk!neil
 Edinburgh
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