Re: [hatari-devel] Unbeatable STF demo works only with STE emulation

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On keskiviikko 04 helmikuu 2015, Nicolas Pomarède wrote:
> Le 04/02/2015 22:11, Eero Tamminen a écrit :
> > One more SillyVenture demo has the same problem as Yanartas;
> > 
> > it's for ST, but works on Hatari only with STE emulation:
> > 	http://www.pouet.net/prod.php?which=64511
> > 	http://demozoo.org/productions/128052/
> > 
> > Interestingly, this demo is for the monochrome monitor.
> 
> that's a bug in the demo. As some comments pointed on pouet.net, the
> demo only works with tos 1.06, which means STE mode.

Thanks, I added this and some other SillyVenture 2014 entries to
 compatibility lists.

I'll add the remaining Payback [1] & Yanartas demos
after their issues have been looked into more.

	- Eero

[1] Doesn't start, with autostarting gives TOS error, otherwise
TOS just returns to desktop:
	http://www.pouet.net/prod.php?which=64683


> The problem is that they test the monochrome resolution at start with a
> wrong code :
> 
> $00012904 : 1039 00ff 8260                     move.b    $ff8260,d0
> $0001290a : 0c00 0002                          cmpi.b    #2,d0
> $0001290e : 6706                               beq.s     $12916
> $00012910 : 4ef9 0002 7bd2                     jmp       $27bd2
> 
> Only bits 0 and 1 are useful, but on STF unused bits 2-7 are sets to 1
> (or random bits). While on the STE unused bits 2-7 are always set to 0.
> 
> So, "cmpi.b #2,d0" can only work on STE ; they should mask unused bits
> before to make it work on STF "and.b #3,d0".
> 
> No bug here, this demo was either tested on an non-accurate emulator or
> only on a STE :)


	- Eero