Demo with two resolutions on the same screen

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Thordarson
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Demo with two resolutions on the same screen

Postby Thordarson » Wed Jan 21, 2009 11:27 am

Hi,

I found some old demos I wrote almost twenty years ago, being in the norwegian group OUCH. I found ut they worked partially on Steem (the latest release), but this one does not work properly. I am not sure if anyone has done this ting before: changing resolution in the middle of the screen. The demo is STE only, and has a bouncing raster bar in the middle of the screen that "splits" the screen in the middle, and in this area the resolution is set to 640x200, with two scrollers at two different speeds. It worked fine on my ordinary 1040 STE back in 1996 (swedish model with rainbow tos, I think), but in Steem the 640x200 area is not showing correctly. The area of screen with 320x200 resolution however works fine, so you only lose the two scrollers when viewing it in Steem.

The demo can be downloaded as a PRG file here: http://www.thordarson.no/share-out/cool_ste.prg
It was just copied straight off a floppy into a PC for several years ago, so it is not MSA or anything - just a plain PRG file.

Maybe I should post this under demos as it is unreleased, but I would like to see it work in Steem...

It would also be nice if someone using real STEs could run this demo and see if it works on their machines, as I only tested it on my own machine...

Regards,
Finn
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Re: Demo with two resolutions on the same screen

Postby Nyh » Wed Jan 21, 2009 1:00 pm

Thordarson wrote:It worked fine on my ordinary 1040 STE back in 1996 (swedish model with rainbow tos, I think), but in Steem the 640x200 area is not showing correctly. The area of screen with 320x200 resolution however works fine, so you only lose the two scrollers when viewing it in Steem.

Strange, the main menu of the Demounstures demo has also both low and medium res and it works without problem under Steem. Display settings:
Borders: Always Show Borders
Low resolution: Double Size - No Stretch
Medium Resolution: Double Height - No Stretch

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Re: Demo with two resolutions on the same screen

Postby Mug UK » Wed Jan 21, 2009 1:31 pm

I'll try it on my STE tonight when I get home.
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Re: Demo with two resolutions on the same screen

Postby Thordarson » Wed Jan 21, 2009 3:36 pm

Strange, the main menu of the Demounstures demo has also both low and medium res and it works without problem under Steem. Display settings:
Borders: Always Show Borders
Low resolution: Double Size - No Stretch
Medium Resolution: Double Height - No Stretch

Hans Wessels


I tried these settings, but it did not help. It flickers a lot, too. It did not flicker that way on my real STE.

But it made the the other demo I found on my hdd drive work fine with side border scrolling - this one works on both ST and STE, I think I will post it under the Demos section.

Will have to check out the Demounstures demo - have never seen other examples on using multiple resolutions in the same screen :)
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Re: Demo with two resolutions on the same screen

Postby Nyh » Wed Jan 21, 2009 5:16 pm

Thordarson wrote:Will have to check out the Demounstures demo - have never seen other examples on using multiple resolutions in the same screen :)

Get the Demounstures demo here: http://pacidemo.atarizone.com/archives/DEMOUNST.ZIP. Warning: it is Omikron basic.

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Re: Demo with two resolutions on the same screen

Postby npomarede » Wed Jan 21, 2009 11:40 pm

Thordarson wrote:Hi,

I found some old demos I wrote almost twenty years ago, being in the norwegian group OUCH. I found ut they worked partially on Steem (the latest release), but this one does not work properly. I am not sure if anyone has done this ting before: changing resolution in the middle of the screen. The demo is STE only, and has a bouncing raster bar in the middle of the screen that "splits" the screen in the middle, and in this area the resolution is set to 640x200, with two scrollers at two different speeds. It worked fine on my ordinary 1040 STE back in 1996 (swedish model with rainbow tos, I think), but in Steem the 640x200 area is not showing correctly. The area of screen with 320x200 resolution however works fine, so you only lose the two scrollers when viewing it in Steem.

The demo can be downloaded as a PRG file here: http://www.thordarson.no/share-out/cool_ste.prg
It was just copied straight off a floppy into a PC for several years ago, so it is not MSA or anything - just a plain PRG file.

Maybe I should post this under demos as it is unreleased, but I would like to see it work in Steem...

It would also be nice if someone using real STEs could run this demo and see if it works on their machines, as I only tested it on my own machine...

Regards,
Finn


Hello,

I tried your demo under Hatari (version 1.2 that should be released shortly). Only the middle scrollers are OK, because Hatari for now has problem with mixed resolution in STE mode with hardware scroll. Maybe it will be fixed in time for 1.2

As for your demo not working correctly, I think the problem may be that when restoring the bottom part of the screen to display the background picture, you're changing ff820f/65/05/07/09 during the active video display (that is before video signal is turned off to display a black right border).
Due to some jitter, these changes are not always at the same place, some of them are in the active display, others are in the right border.
From an emulation point of view, it is very hard to emulate the behaviour of the shifter when you change these video registers while the shifter is displaying data.

In Hatari, such changes are postponed to the beginning of the next line ; I don't know Steem's policy but it surely confuses it.

So, try to restore those registers 60 cycles or so later, to be sure you're doing it while in the right border (you have time to do it until you exit left border on the next line and display is on again), this should fix the problem (and even on a real STE, you should not change these during active display as this could also create some artecfacts).

As for Nyh demo, Hatari doesn't support more than one palette per line in mid res for now.

Regarding mixing low/mid res, I think the very first programs that did this were the games from Magnetic Scrolls in 1986 (The Pawn, Guild of Thieves, Jinxter, ... such memories from that time !)
I think some painting programs also used mixed mode to display the image in low res and the tools in med res in the bottom of the screen (perhaps a version of Neochrome did that, can't remember)


Nicolas

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Re: Demo with two resolutions on the same screen

Postby Thordarson » Sun Jan 25, 2009 3:59 pm

I tried your demo under Hatari (version 1.2 that should be released shortly). Only the middle scrollers are OK, because Hatari for now has problem with mixed resolution in STE mode with hardware scroll. Maybe it will be fixed in time for 1.2


Interesting. I tried to run it in version 1.1, made an ST image, but it bombed out with two bombs using tos 2.06 and error message with emutos. Nice if it could work in 1.2!

As for your demo not working correctly, I think the problem may be that when restoring the bottom part of the screen to display the background picture, you're changing ff820f/65/05/07/09 during the active video display (that is before video signal is turned off to display a black right border).
Due to some jitter, these changes are not always at the same place, some of them are in the active display, others are in the right border.
From an emulation point of view, it is very hard to emulate the behaviour of the shifter when you change these video registers while the shifter is displaying data.

In Hatari, such changes are postponed to the beginning of the next line ; I don't know Steem's policy but it surely confuses it.

So, try to restore those registers 60 cycles or so later, to be sure you're doing it while in the right border (you have time to do it until you exit left border on the next line and display is on again), this should fix the problem (and even on a real STE, you should not change these during active display as this could also create some artecfacts).


It sounds sensible. I think maybe it could be an idea to use the same method to stabilize the timing as in opening side borders (bit shifting after reading exact position), so that the changes appear in the exact same position every time, as I can see that the lower part flickers in a way that seems to be caused by timing variations. I also saw it might be some flickering on the raster lines too at the ends of the lines which I did not see back twenty years ago as it the monitor did not display the lines all the way.

Regarding mixing low/mid res, I think the very first programs that did this were the games from Magnetic Scrolls in 1986 (The Pawn, Guild of Thieves, Jinxter, ... such memories from that time !)
I think some painting programs also used mixed mode to display the image in low res and the tools in med res in the bottom of the screen (perhaps a version of Neochrome did that, can't remember)


There you awoke memories! I remember seeing the title picture of Jinxter for the first time, I was genuinely impressed. I have a feeling of that graphics on Atari ST was art, human hand-made art, while most PC graphics today is made by rendering of models, digitalising of photography/video recordings, not giving the same impression of beauty and art.
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Re: Demo with two resolutions on the same screen

Postby npomarede » Sun Jan 25, 2009 6:22 pm

Thordarson wrote:
I tried your demo under Hatari (version 1.2 that should be released shortly). Only the middle scrollers are OK, because Hatari for now has problem with mixed resolution in STE mode with hardware scroll. Maybe it will be fixed in time for 1.2


Interesting. I tried to run it in version 1.1, made an ST image, but it bombed out with two bombs using tos 2.06 and error message with emutos. Nice if it could work in 1.2!


Yes, I fixed this in Hatari 1.2, the demo works correclty and doesn't flicker (tested with tos 1.62 and STE)


It sounds sensible. I think maybe it could be an idea to use the same method to stabilize the timing as in opening side borders (bit shifting after reading exact position), so that the changes appear in the exact same position every time, as I can see that the lower part flickers in a way that seems to be caused by timing variations. I also saw it might be some flickering on the raster lines too at the ends of the lines which I did not see back twenty years ago as it the monitor did not display the lines all the way.

Yes, this would be the safest way ; you loose one line to synchronise but you gain stable behaviour.

There you awoke memories! I remember seeing the title picture of Jinxter for the first time, I was genuinely impressed. I have a feeling of that graphics on Atari ST was art, human hand-made art, while most PC graphics today is made by rendering of models, digitalising of photography/video recordings, not giving the same impression of beauty and art.


Well, I wouldn't go that far :) but graphics like these ones back in that time in 1986 surely showed the huge gap between 8 bit machines and Atari/Amiga. What was nice with The Pawn and other is that despite the high number of images in the game and the necessary compression, you still had the feeling of very good quality drawings.

Nicolas

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Re: Demo with two resolutions on the same screen

Postby Steven Seagal » Sun Mar 25, 2012 9:48 am

The link is dead. Anybody kept this demo (1st post), I'd like to check it?
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Re: Demo with two resolutions on the same screen

Postby nativ » Sun Mar 25, 2012 11:20 am

Steven Seagal wrote:The link is dead. Anybody kept this demo (1st post), I'd like to check it?


neither of the links appear to work
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Re: Demo with two resolutions on the same screen

Postby npomarede » Sun Mar 25, 2012 11:45 am

Here's the .PRG file I downloaded at that time.

Nicolas
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Re: Demo with two resolutions on the same screen

Postby Steven Seagal » Sun Mar 25, 2012 4:03 pm

Thanks! It's cool that you kept this. At first glance it doesn't work in Steem.

EDIT:

There are 2 problems in Steem. 1st, STE scrolling in medium res wasn't really handled. 2nd, the writes to SDP just after the end of scanline were sometimes misinterpreted, and the "linewidth" (extra words) was applied.
I can make it run better, still some minimal flicker I can't explain, contrary to Hatari :(
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