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Atari demoscene BBS
| Re: Atari ST demo tricks history |
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Posted by: Alien ST/CNX
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Sep,28.2007-20:44
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The trace-A trick was also used by OVR. I published it in my ST Mag Overscan articles, so you can get the source of an Overscan "Intergrator" there. Basically you sync and read the video counter, run the instruction using trace-A, read the video counter, subtract the 2 video counter values, and subtract the two times. You calibrate using the fact you know a nop takes 4 cycles. It works for most instructions (except those with weird paring which were slow anyway, and those with non-constant time (think mul/div)).
The MMU trick is quite amusing. I can't remember the details. But basically if you turn memory config to 0K (or something else invalid... a bit hazy here), memory is wiped -- EXCEPT crucially the lower first Kb... so run some code doing some rubbish. Nuke the MMU config but continue doing rubbish. Set up a timer to catch yourself (long before). Boom! the debugger and memory is flushed, but your timer routine can load the next sectors off disk and you're none the wiser. (as long as it fit in the first Kb). Anyway now you know why we never got around to releasing the Bless Dis Mess demo. Too much fun doing other things... (and doing homework). This was only tested on my STf, so YMMV.
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Topic
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Date
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Atari ST demo tricks history
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Shazz/MJJ Prod
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Sep,22.2007-14:02
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Re: Atari ST demo tricks histo
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havoc
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Sep,22.2007-14:06
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Sep,22.2007-14:33
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Re: Atari ST demo tricks histo
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earx
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Sep,22.2007-18:45
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Sep,24.2007-19:21
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Re: Atari ST demo tricks histo
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ear
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Sep,25.2007-16:46
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Re: Atari ST demo tricks history
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Alien ST/CNX
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Sep,26.2007-20:54
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Re: Atari ST demo tricks history
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ggn
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Sep,27.2007-12:01
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Re: Atari ST demo tricks history
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Alien ST/CNX
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Sep,28.2007-20:44
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Re: Atari ST demo tricks history
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Bod/STAX
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Oct,18.2014-13:32
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Sep,28.2007-11:26
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Re: Atari ST demo tricks histo
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Alien ST/CNX
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Sep,28.2007-20:47
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Oct,01.2007-15:14
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Re: Atari ST demo tricks histo
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Alien/ST-CNX
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Oct,18.2014-07:55
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Re: Atari ST demo tricks histo
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earx
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Sep,28.2007-14:30
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Oct,01.2007-15:18
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Re: Atari ST demo tricks histo
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corbo
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Oct,05.2007-20:57
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Re: Atari ST demo tricks histo
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Shazz/MJJ Prod
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Oct,06.2007-16:01
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Re: Atari ST demo tricks histo
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Chuck / Dune
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Oct,06.2007-23:00
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Re: Atari ST demo tricks histo
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corbo
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Oct,15.2007-14:41
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Re: Atari ST demo tricks histo
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corbo
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Oct,15.2007-14:39
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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