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