Re: [hatari-devel] Yanartas demo doesn't work in ST mode

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 03/02/2015 22:42, Eero Tamminen a écrit :
> Hi,
>
> I checked another Sillyventure demo, Yanartas:
> 	http://demozoo.org/productions/128065/
> 	http://www.pouet.net/prod.php?which=64736
>
> This is supposed to be ST demo, but works only in STE mode with
> current Hatari.
>
> In ST mode it freezes after the bouncing cursor at start, both
> with WinUAE and oldUAE CPU core (and older WinUAE CPU core).
> With Hatari v1.6.2, Hatari itself freezes right at the demodisk boot.

Hi

top border removal code has rather short timings, it mostly works "by 
luck" because the VBL interrupt has a small jitter on ST.

But at one point, the jitter becomes 0 and top border is removed 8 
cycles too soon and fails, which then stops the demo from going further.

As STE has slightly different timings, this explains why it works in STE 
and not STF.
Also the video on dhs.nu was recorded with Hatari 1.8, so it should work 
with 1.8, but I guess it was in STE mode ?

I would need to try it on my STF to check if it really works, maybe they 
just tested it using an STE ?

Of course, if it works on STF, then there will be something to fix in 
Hatari :)

Nicolas