NTSC and PAL demos?

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NTSC and PAL demos?

Postby Zamuel_a » Tue Nov 29, 2011 9:05 am

I wonder how common it was/are to make demos for the Atari in US since they have the NTSC system and all I ever heard about was PAL demos from Europe. Since most demos use precise timing to 50Hz it seems like most demos are not workable in US at all. 60Hz gives less time to do stuff to and I'm not sure if an NTSC TV can run in 50Hz as good as most PAL TVs could run in 60Hz. Is it possible to break the borders from 60Hz to for full screen effects?
Maybe they had a big demo scen i US that we didn't hear so much about since it's not compatible. I guess with an RGB monitor it shouldn't matter since they must be the same for both US and Europe?
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Re: NTSC and PAL demos?

Postby christos » Tue Nov 29, 2011 10:28 am

The new paradox demos are all 60Hz. Maybe someone can check on an ntsc STE?
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Re: NTSC and PAL demos?

Postby nativ » Tue Nov 29, 2011 11:18 am

Interesting point!

Alot of demos use switching techniques aswell! between 50hz and 60hz! and some 70hz! (hi colour demo)

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Re: NTSC and PAL demos?

Postby DarkLord » Tue Nov 29, 2011 1:59 pm

Er...very few demo's I've tried on ST/STe didn't work...
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Re: NTSC and PAL demos?

Postby ijor » Wed Nov 30, 2011 3:55 am

The overscan and sync scroll techniques don't actually change the display refresh frequency. They modify the sync freq registers only momentarily. And except for a couple of cases, these changes don't alter the actual sync signals in any way whatsoever.

However, allmost all demos using this technique will work at 50 Hz only. It is possible to do some border removal at 60 Hz, but not nearly as much as at 50 Hz. Software overscan at 60 Hz was hardly ever used, if at all.

As the OP is saying, the whole thing is not an issue when using an Atari monitor (or any other similar RGB monitor for that matter). When using the TV output, you would get a "mixed" signal, NTSC but at 50 Hz. And the result depends completely on the specific TV (or monitor, or capture device). Some TVs would take it without problems, others would display in black and white, some multinorm ones would require you to force NTSC (disabling the AUTO option), and some would probably refuse to display anything at all.
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Re: NTSC and PAL demos?

Postby Cyprian » Wed Nov 30, 2011 9:27 am

ijor wrote: It is possible to do some border removal at 60 Hz, but not nearly as much as at 50 Hz. Software overscan at 60 Hz was hardly ever used, if at all.

let me guess, Left and Right border we can remove at 60Hz, and what about Top and Bottom?
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Re: NTSC and PAL demos?

Postby ijor » Fri Dec 02, 2011 7:50 am

Cyprian_K wrote:let me guess, Left and Right border we can remove at 60Hz, and what about Top and Bottom?


To be honest, I'm not sure without checking.
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