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#81 |
Registered User
Join Date: Oct 2013
Location: Hamburg
Posts: 70
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What what what!!!
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#82 |
Registered User
Join Date: Jun 2010
Location: PL?
Posts: 2,919
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KUDOS to You ALL Guys!
@Ross - my naive way of thinking leading me to conclusion that somehow it is possible to start displaying video on OCS earlier than Denise hard-coded value... CPU & &DFF02C? Or it is more tricky to convince Denise to output video earlier than normally? |
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#83 | |
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,534
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Quote:
Denise is virtually blind and obeys any input from Agnus. The only thing it knows is that an internal counter has been started and running (sync to x beam) and that in certain 'positions' it has to 'handle' some data and send to video device. Hardcoded value in Agnus are absolute (only from ECS are programmable), so you have to trick it somehow. So what you wrote is right, but it's just the starting point, finding a way to apply it is the difficult thing ![]() * I added the word "right" because it is important. 'data' was too generic and made one think exclusively of 'graphic data' (bitplanes and/or sprites). But Agnus also manages other 'data', including strobe signals, to impose what type of video line you are viewing (or not.), and when something should happen on the y coordinate. This is a big hint in understanding how to trick Denise ![]() Last edited by ross; 10 December 2023 at 12:55. |
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#84 | |
Registered User
Join Date: Jun 2010
Location: PL?
Posts: 2,919
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Quote:
No doubt on this - that's why i've ask not provide answers - i recall it was very easy to create 625 progressive @25Hz by "enlarging" display trough proper writing to VHPOSW. Whenever i've tried to write into STRobe registers (perhaps except $DFF03E) system crashed so at some point i've simply give up. Hope at some point this information will be available - worse case scenario i will build (or buy) 24..32 Ch logic analyzer to get proper system sequence STRx registers. |
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#85 | |
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,534
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Quote:
There is also an undocumented effect on Denise's counter writing directly on VHPOSW, if I'm not wrong you should find reference in the appropriate thread. |
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#86 |
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 49
Posts: 26,611
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Yes, you don't want to mess with the strobes directly because strobes are also used for memory refresh (mysterious random memory changes can happen) and Paula also listens for strobes (if audio or disk DMA is active: it breaks and out of sync DMAL with Agnus will cause DMA conflicts = very strange crashes).
Indirectly via VPOSW writes do work but it needs cycle-accurate writes with cycle-accurately calculated value(s). Even single cycle error can mess up everything or cause display device to lose sync. Including messing up strobes indirectly if timed badly. |
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#87 |
Ex nihilo nihil
Join Date: Oct 2017
Location: CH
Posts: 5,148
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3rd of July 2024 swiss teletext celebrated it's 40 years anniversary.
According to the news, it still has 1.6 million regular users which is more than TikTok, X or LinkedIn... and is still used in 2024 in : CH, DE, AT, IT, ES, PT, NO, FI, SE, NL, CZ and PL. https://www-24heures-ch.translate.go...x_tr_hist=true ![]() Last edited by malko; 08 August 2024 at 00:22. |
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#88 |
Defendit numerus
Join Date: Mar 2017
Location: Crossing the Rubicon
Age: 54
Posts: 4,534
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#89 |
Ex nihilo nihil
Join Date: Oct 2017
Location: CH
Posts: 5,148
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