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horizontal scrolling on ST
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- Fuji Shaped Bastard
- Posts: 2745
- Joined: Mon Aug 06, 2018 3:05 pm
Re: horizontal scrolling on ST
Btw, just another idea with STe: since the prefetch causes +1 word to read, the total number of words will be 116/scanline instead of 115 when both borders are opened. And this is divisible by 4, so it won't confuse the shifter (there will be no word left in it). I wonder if it is used already. Just need to set the hscroll value to something which is not zero.
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- Atari User
- Posts: 37
- Joined: Sun Jan 22, 2017 12:10 pm
Re: horizontal scrolling on ST
http://www.atari-forum.com/viewtopic.ph ... 00#p396735
https://github.com/frankheisig71/st_side_scrl
Maybe someone can check this out and test
https://github.com/frankheisig71/st_side_scrl
Maybe someone can check this out and test

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- Atari God
- Posts: 1799
- Joined: Mon Apr 30, 2012 6:20 pm
- Location: Sweden
Re: horizontal scrolling on ST
Update to the topic of ljbk's 4-bit beescroll:
A while back Ijor made an off-hand comment in a thread related to knowledge he's gained from decapping the Shifter. I made a note of it, since it seemed to be useful for Shifter-caused effects. I've verified that it can both be used for an Alien style 4-bit fullscreen sync scroller as well as an ljbk-style "one switch per frame" non-fullscreen scroll.
However - it fails in the same way as ljbk's, because of the same reason, in some wakestates and Shifter mode. I don't think there's a solution to that lacking offset in WS1 and sometimes-WS3. It's simply the result of the Reload-pulse happening at the "right" place.
/Troed
A while back Ijor made an off-hand comment in a thread related to knowledge he's gained from decapping the Shifter. I made a note of it, since it seemed to be useful for Shifter-caused effects. I've verified that it can both be used for an Alien style 4-bit fullscreen sync scroller as well as an ljbk-style "one switch per frame" non-fullscreen scroll.
However - it fails in the same way as ljbk's, because of the same reason, in some wakestates and Shifter mode. I don't think there's a solution to that lacking offset in WS1 and sometimes-WS3. It's simply the result of the Reload-pulse happening at the "right" place.
/Troed