Commercial games using sync scrolling

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Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 8:57 am

For a long time I believed the only commercial game to ever use "demo scene" sync scrolling on ST was Enchanted Lands. However, I've recently been told that No Buddies Land does as well* - and yesterday I saw on the Lethal Xcess website (http://www.edv-rudolf.de/lethal-xcess/tech.htm) that it also uses sync scrolling.

Are there any others? Please help me fill in the list:

    Enchanted Lands
    Lethal Xcess
    No Buddies Land
    Leavin' Teramis
    Chambers of Shaolin (end credits)

/Troed

*) From what I've been told No Buddies Land doesn't use the regular line length difference method to create 2 byte offsets for horizontal/vertical scrolling, but 0-byte lines to get (only) vertical scroll. A clean way of doing that wasn't discovered until 2006/2012, with full knowledge of ST wakestates, and without having tested it myself I would expect the method used in NBL to cause visible distortion on quite a few monitors/TVs.
Last edited by troed on Fri Apr 15, 2016 1:19 pm, edited 4 times in total.

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Re: Commercial games using sync scrolling

Postby prog99 » Fri Apr 15, 2016 9:02 am

I was fairly certain that Leaving Teramis did?
And was there not an end screen in chambers of shaolin that used it too?
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Re: Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 9:13 am

xerud wrote:I was fairly certain that Leaving Teramis did?
And was there not an end screen in chambers of shaolin that used it too?


Ah, Leavin' Teramis was even mentioned on the Lethal Xcess page .. :) Thanks

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Re: Commercial games using sync scrolling

Postby swapd0 » Fri Apr 15, 2016 10:56 am

Wings of death

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Re: Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 11:01 am

swapd0 wrote:Wings of death


Not according to the Lethal Xcess website.

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Re: Commercial games using sync scrolling

Postby prog99 » Fri Apr 15, 2016 11:18 am

troed wrote:
swapd0 wrote:Wings of death


Not according to the Lethal Xcess website.

Or in this article/press release from Richard Karsmakers
http://thethalionsource.w4f.eu/Artikel/ ... e_news.htm
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Re: Commercial games using sync scrolling

Postby npomarede » Fri Apr 15, 2016 12:13 pm

Wasn't there that vertical shoot em up that was never released (made by Eclipse maybe, can't remember). IIRC there was a non playable demo version of it and as it was supposed to have huge technical features, maybe it used syncscroll too.

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Re: Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 12:20 pm



Let's take that as confirmation of it being used for end credit scrolling in Chambers of Shaolin as well. Can't be bothered to play through and didn't see it in a Youtube capture ;)

/Troed

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Re: Commercial games using sync scrolling

Postby ijor » Fri Apr 15, 2016 12:27 pm

troed wrote:*) From what I've been told No Buddies Land doesn't use the regular line length difference method to create 2 byte offsets for horizontal/vertical scrolling, but 0-byte lines to get (only) vertical scroll. A clean way of doing that wasn't discovered until 2012, with full knowledge of ST wakestates, and without having tested it myself I would expect the method used in NBL to cause visible distortion on quite a few monitors/TVs.


I remember looking into No Buddies Land. IIRC, it disables complete lines by switching to mono at HSYNC time. Of course, it alters sync. But I think it didn't produce any visible distortion in most CRTs. At least I don't remember anybody reporting something. Of course, on a modern digital LCD (possibly even a digitally controlled CRT), all odds are off.

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Re: Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 12:28 pm

npomarede wrote:Wasn't there that vertical shoot em up that was never released (made by Eclipse maybe, can't remember). IIRC there was a non playable demo version of it and as it was supposed to have huge technical features, maybe it used syncscroll too.


Are you referring to Synchron Assembly's (Omega's) Eutanasia? There's a playable version. Talked with Liesen about it at STNICCC but I never asked about tech specs ..

http://demozoo.org/productions/148392/

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Re: Commercial games using sync scrolling

Postby troed » Fri Apr 15, 2016 12:31 pm

ijor wrote:I remember looking into No Buddies Land. IIRC, it disables complete lines by switching to mono at HSYNC time. Of course, it alters sync. But I think it didn't produce any visible distortion in most CRTs. At least I don't remember anybody reporting something. Of course, on a modern digital LCD (possibly even a digitally controlled CRT), all odds are off.


Yeah Nicolas told me it cancels HSYNC end - which causes my flatscreen (Dell 2001FP - handles all ST modes on VGA input) immediately goes out of sync. I haven't tried with the game myself though, that's only what my own tests indicate.

/Troed

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Re: Commercial games using sync scrolling

Postby npomarede » Fri Apr 15, 2016 12:43 pm

troed wrote:
npomarede wrote:Wasn't there that vertical shoot em up that was never released (made by Eclipse maybe, can't remember). IIRC there was a non playable demo version of it and as it was supposed to have huge technical features, maybe it used syncscroll too.


Are you referring to Synchron Assembly's (Omega's) Eutanasia? There's a playable version. Talked with Liesen about it at STNICCC but I never asked about tech specs ..

http://demozoo.org/productions/148392/

/Troed

Yes, that's this one. I gave it a look, and it's just standard software scrolling, no freq/res switches involved ; on the other hand, as the game use 2 layers of parallax scroll, syncscroll would still require to refresh one of the 2 layers, so maybe it would not be such a huge gain. Or maybe they never had time to finish it to add syncscroll support :)
Last edited by npomarede on Fri Apr 15, 2016 12:47 pm, edited 1 time in total.

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Re: Commercial games using sync scrolling

Postby npomarede » Fri Apr 15, 2016 12:45 pm

troed wrote:
ijor wrote:I remember looking into No Buddies Land. IIRC, it disables complete lines by switching to mono at HSYNC time. Of course, it alters sync. But I think it didn't produce any visible distortion in most CRTs. At least I don't remember anybody reporting something. Of course, on a modern digital LCD (possibly even a digitally controlled CRT), all odds are off.


Yeah Nicolas told me it cancels HSYNC end - which causes my flatscreen (Dell 2001FP - handles all ST modes on VGA input) immediately goes out of sync. I haven't tried with the game myself though, that's only what my own tests indicate.

/Troed

And I tried it in a custom test program on my old CRT I used with my STF, and I get image bending too. In my case, the test is around hbl 200, maybe the CRT is more tolerant if switches are made at line 63 as in the game ?
I would need to try the real game on my STF/CRT though, I will dump an .ST image of it on a floppy to check.

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Re: Commercial games using sync scrolling

Postby ijor » Fri Apr 15, 2016 3:05 pm

npomarede wrote:And I tried it in a custom test program on my old CRT I used with my STF, and I get image bending too.


But it wasn't an Atari monitor, right?

Btw, I updated the HSYNC seudo code. I added how HSYNC affects hDE (and hBLANK). Because the state machine model doesn't actually describe what happens here. HSYNC resets hDE during the whole HSYNC, not just at the start.

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Re: Commercial games using sync scrolling

Postby npomarede » Fri Apr 15, 2016 5:33 pm

ijor wrote:But it wasn't an Atari monitor, right?

No, that was another brand (Philips). I would need to check the famous "xxx international demos" too, as it was famous for opening top border by staying into 60 Hz during 33 HBL, creating huge bending on many CRT, I don't remember if my Philips monitor worked ok or not with this one.

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Re: Commercial games using sync scrolling

Postby npomarede » Mon Apr 18, 2016 6:51 pm

Hi
I made more tests on real ST + CRT for "No Buddies Land".
The game uses the hi/lo switch at pos 500, which creates a blank signal on next line and disrupt sync.
As we know, such sync disrupting are known to create horizontal bending of the display on the following lines.
In the case of the game, I think they were aware of this side effect, to minimize it on screen, they used several things :
- although only 5 lines max are required to move the screen vertically in that case, you can see that screen is black from lines 63 to ~83. This 20 black lines with no pixel shown will allow to hide the bending if it remains small
- scroll is not continuous : you only scroll when jumping at a certain point, then screen will scroll up quickly, so blank lines will be enabled for less than 1 sec, which will also lower the time during which hsync is altered, avoiding too much alteration of the screen (the game is made in such a way that it's very rare to be able to scroll up often).
On my CRT monitor, by turning luminosity to the max, I can the screen bending at line 63 when scrolling, but image remains stable (on the other end, the XXX international demo will fully bend my CRT when removing top border). The game also works fine on my LCD TV.
So, this method seems rather stable when compared to other lines where sync is altered. You just need a little extra cheating to hide the next lines and avoid showing too much of what is happening :)

Nicolas

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Re: Commercial games using sync scrolling

Postby ijor » Tue Apr 19, 2016 11:54 am

npomarede wrote:I made more tests on real ST + CRT for "No Buddies Land"....


Interesting.

There is a well known demo that uses a similar technique. IIRC, not exactly the same. I'm afraid I don't remember the name of the demo.

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Re: Commercial games using sync scrolling

Postby npomarede » Tue Apr 19, 2016 12:11 pm

ijor wrote:
npomarede wrote:I made more tests on real ST + CRT for "No Buddies Land"....


Interesting.

There is a well known demo that uses a similar technique. IIRC, not exactly the same. I'm afraid I don't remember the name of the demo.

There's a screen by NGC in the Delirious Demo IV which uses this hi/lo switch at pos 500 (but I think it's a bug in the demo and it was not wanted, as this line has no real use in this demo).
Also the screen by Lemmings in the Nostalgic demo by Oxygene uses the same kind of blank lines to shift the bottom part of the screen by going hi/lo at pos 28 (so this will scroll down the rest of the screen, as DE is not enabled)
And the demo 'Beyond' by Kruz uses the hi/lo switch at pos 460 without removing right border, which causes a blank line with no DE on the next line.

Regarding "No Buddies Land", my test program on STF shows a large bending when doing hi/lo at pos 500, but in my case I use bright value for color 0. Could the use of $000 (black) for color 0 help lower the bending artifacts (because black color would have a voltage close to the blank signal, or sthg like that ?). I will do some tests on my STF to see if the choice of the color alter the banding.

Nicolas

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Re: Commercial games using sync scrolling

Postby npomarede » Wed Apr 20, 2016 8:24 pm

I made a few more extra tests, and the choice of the color (between black as in the game, or a very bright color) doesn't affect the bending effect, it stays the same.
Even when doing 10 consecutive hi/lo at pos 500, the bending remains low on my CRT (less than 5-6 pixels) and propagate on only a few lines after, so it can be easily hidden by adding 20 black lines after, as game does.

Now, I don't know why they chose this method ; this reduced the display area to 180 lines, so they could have removed the top border to put the scroll part there and don't loose so many lines. Or use some more "classic" hardscroll using 7-8 lines, which were known to be rather stable for nearly the same cpu cost.
Well, at least that makes an interesting case to look at :)

Nicolas

edit : "by adding 20 black lines after", not "20 blank lines"
Last edited by npomarede on Sat Apr 23, 2016 9:18 am, edited 1 time in total.

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Re: Commercial games using sync scrolling

Postby ijor » Sat Apr 23, 2016 2:57 am

npomarede wrote:I made a few more extra tests ...


Nice.

Could the use of $000 (black) for color 0 help lower the bending artifacts (because black color would have a voltage close to the blank signal, or sthg like that ?)


Black color IS usually the blank level. I know that TV theory describes they are supposed to be different, and may be they really are in some video equipment. But in all the VGA and similar (as the ST) systems I've seen, blank is just the black color.

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Re: Commercial games using sync scrolling

Postby npomarede » Sat Apr 23, 2016 9:25 am

ijor wrote:Black color IS usually the blank level. I know that TV theory describes they are supposed to be different, and may be they really are in some video equipment. But in all the VGA and similar (as the ST) systems I've seen, blank is just the black color.

On my CRT monitor, if I turn brightness to the max, black color becomes some kind of bright grey and in that case it's possible to see a slight difference between black used as color 0 in the borders for example and the blank signal. With this, you can see the difference between a hi/lo stabiliser around cycle 450 (which prevents blank from starting) and a med/lo stabiliser (which doesn't alter blank start), so I think there's a small level difference.
But the color difference between black and blank is really subbtle, it's not noticeable in the case of a CRT where brightness is correctly "calibrated'" (whatever this means on old 30 years crt :) )

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Re: Commercial games using sync scrolling

Postby troed » Sat Apr 23, 2016 10:20 am

ijor wrote:Black color IS usually the blank level. I know that TV theory describes they are supposed to be different, and may be they really are in some video equipment. But in all the VGA and similar (as the ST) systems I've seen, blank is just the black color.


From memory: On my STFMs blank is a "blacker black". On my STEs I can't see the difference. This on both my CRT and my flatscreen IIRC.

... and I have now verified (I needed to connect a joystick .. ) that No Buddies Land indeed goes out of sync on my Dell 2001FP LCD monitor (accepts all ST resolutions on the VGA input). When scrolling the screen becomes completely black and then comes back.

All the publishers who were worried about making games using demo scene tricks are thus a tiny bit vindicated, although this game is alone in using the old 0-byte method compared to different line lengths,

/Troed

edit: Also, I tested this on STE which means NBL uses the same code path for both ST and STE instead of using STE hw for its scroll routines.

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Re: Commercial games using sync scrolling

Postby ijor » Sat Apr 23, 2016 12:45 pm

npomarede wrote:On my CRT monitor, if I turn brightness to the max, black color becomes some kind of bright grey and in that case it's possible to see a slight difference between black used as color 0 in the borders for example and the blank signal.


Interesting. On which ST model do you see that? May be a very subtle difference in some STf, but it shouldn't happen on the STe that integrates BLANK logic inside STe SHIFTER.

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Re: Commercial games using sync scrolling

Postby npomarede » Sat Apr 23, 2016 1:31 pm

ijor wrote:
npomarede wrote:On my CRT monitor, if I turn brightness to the max, black color becomes some kind of bright grey and in that case it's possible to see a slight difference between black used as color 0 in the borders for example and the blank signal.


Interesting. On which ST model do you see that? May be a very subtle difference in some STf, but it shouldn't happen on the STe that integrates BLANK logic inside STe SHIFTER.

This is with my old 520 STF from 1988 (single sided internal floppy drive). On 'Closure' for example if I set brightness to the max I can clearly see when you activate blank lines during the syncscroll, it's darker than the black used for color 0.

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Re: Commercial games using sync scrolling

Postby AtariCrypt » Tue Apr 04, 2017 5:11 pm

Sorry to drag this old topic up again, but No Buddies also blanks out the screen on my STe. I've tried PP's adaptation along with the Fuzion CD 152 :-(
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