[hatari-devel] Falcon emu and STE compatibility (D-Bug games)

[Thomas Huth]

Am Thu, 17 Feb 2011 23:13:02 +0100
schrieb Laurent Sallafranque <laurent.sallafranque at free.fr>:

> I'm pretty sure they use register $ff8007.b (Bit 0)  for this (I'll 
> check tomorrow).
> 
> Is there a way for us to switch the CPU speed of Hatari from 16 Mhz
> to 8 Mhz (or from 8 Mhz to 16 Mhz) on the fly (while Hatari runs) ?

You could try to modify the nCpuFreqShift variable... it is used to
scale the CPU frequency (see M68000_AddCycles() in m68000.h).


> - When bit 5 of register $ff8007.b is clear (I'll check this too 
> tomorrow), all STe specific addresses (like shadow addresses) become 
> allowed.

Yes, if I remember correctly, the STE Bus mode bit can be used to
disable the bus errors for certain memory regions, including the PSG
shadow registers.

I once measured this behaviour with my bus error testing program, you
can find the results for this STE-Bus mode in the following two files:

tests/buserror/results/fal_c_b.txt & tests/buserror/results/fal_c_w.txt

 Regards,
  Thomas