|Re: [hatari-devel] POV 136 & STE emulation?|
[ Thread Index |
| More lists.tuxfamily.org/hatari-devel Archives
On 16/02/2012 22:45, Eero Tamminen wrote:
POV 136 demo disk doesn't work properly with Hatari STE emulation.
It complains that there's STE HW missing required for the demos?
The STE detection code is not very good :
$00d3a6 : 4bf8 8205 lea $ffff8205.w,a5
$00d3aa : 1e15 move.b (a5),d7
$00d3ac : 1abc 004d move.b #$4d,(a5)
$00d3b0 : be15 cmp.b (a5),d7
$00d3b2 : 6700 000c beq $d3c0
$00d3b6 : 1a87 move.b d7,(a5)
$00d3b8 : 33fc ffff 0003 f808 move.w #$ffff,$3f808
Unfortunately, Hatari doesn't support modifying $ff8205 and reading it
back while display is enabled (while the shifter shows some pixels).
As this routine doesn't sync with VBL, it writes/reads at random time
during the VBL, so there's a 10% chance or so that you might be able to
be detected as an STE
Maybe moving the mouse or pressing the keys can alter the timings while
tos is starting the program to get a chance the read happens at the
Certainly not the best way to detect an STE ; trying to access dma sound
is often more precise at it doesn't involve video timings, even on a