Posted By
crimefighter_sweden
on 2021-06-01
06:27:57
|  newbie question: double buffering possible?
Hi! I am dabbling with my first Plus/4 program, and I try to do a full screen character scroll (40*25 characters + 40*25 colors).
I can write a routine which moves all 2k of data within the time of one raster frame, so I get full frame rate, but as it takes quite a lot of time to move such an amount of data, it creates an undesired tearing effect when the screen is painted with data which is being moved at the same time. It does not help to start the copying when the raster enters the lower border, as the copying is still running when it enters at the top again.
Is there a way to implement double buffering regarding the text video matrix at $0c00? So you could have two matrices, and move data on the one not being displayed? I have tried writing to HIBASE $053E "Base location of screen", but I guess it's read-only or something.
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Posted By
SVS
on 2021-06-01
07:28:42
 | Re: newbie question: double buffering possible?
Yes you can switch more screen-matrixes by setting $FF14 TED register. Keep in mind that here you have to set the matrix's address. The attributes's address table is automatically set $400 bytes above.
See Ultimate Map (TED&Music page for TED registers, and GraphicModes page for details and Screen Codes online Calculator).
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Posted By
crimefighter_sweden
on 2021-06-01
09:45:03
| Re: newbie question: double buffering possible?
Sir,
that is one super useful piece of information, and an equally useful map! Thanks a lot! You saved me here!
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Posted By
Doug
on 2021-06-01
13:32:31
| Re: newbie question: double buffering possible?
It sure is. Definitely look at the Ultimate Map. I use double buffering in The Pit.
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Posted By
crimefighter_sweden
on 2021-06-02
06:27:15
| Re: newbie question: double buffering possible?
The Pit looks extremely awesome! The rich colour scheme makes it very appealing too - I need to learn more about the Plus/4 colours.
Thanks again, I have now gotten the double buffering working with your help - I'm having a blast here with ca65 and xplus4 (don't have a real machine but that's ok). The Ultimate map has provided more help with various things already.
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Posted By
Luca
on 2021-06-02
09:57:31
 | Re: newbie question: double buffering possible?
crimefighter_sweden: xplus4 VICE has mediocre emulation, prefer using YAPE instead. Of course, doublebuffer is a very often used practice when needed.
Btw Doug you shoud better put in evidence the forthcoming commercial version of The Pit, currently on the Psytronik site as TBA...
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Posted By
Doug
on 2021-06-02
16:08:09
| Re: newbie question: double buffering possible?
Luca thanks for the nudge on the commercial release. Last time I heard from Kenz was 3 months ago, and it was all systems go at that point. Definitely time to ask him what gives!
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Posted By
MIK
on 2021-06-02
23:38:40
 | Re: newbie question: double buffering possible?
Nice one Doug! A physical version of The Pit in ya hands will be awesome! 
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Posted By
Doug
on 2021-06-03
14:32:37
| Re: newbie question: double buffering possible?
The word from Kenz is that it will be available in July. Start saving your pocket money 
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Posted By
Mad
on 2021-06-03
14:35:07
| Re: newbie question: double buffering possible?
So.. Saving money for that now!
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