[hatari-devel] Little question with relative_interrupts

[npomarede at corp.free.fr]

On Wed, 16 Sep 2009, Laurent Sallafranque wrote:

> Hello,
>
> While reading code in int.c and int.h (for the crossbar), I asked me the
> following question :
>
> Extract from int.c
>
>  Thanks to Arnaud Carre (Leonard / Oxygene) for sharing this method
> used in Saint (and also
>  used in sc68).
>
>  Conversions are based on these values :
>    real MFP frequency is 2457600 Hz
>    real CPU frequency is 8021247 Hz (PAL european STF), which we round
> to 8021248.
>
>  Then :
>    8021248 = ( 2^8 * 31333 )
>    2457600 = ( 2^15 * 3 * 5^2 )
>
>  So, the ratio 8021248 / 2457600 can be expressed as 31333 / 9600
>
>
> Are these values still OK for a falcon (where the CPU is ~16 000 000 and
> not 8 021 248 ?
>
> If no, would this explain that some demos/games need to run at 32 Mhz ?
>
> Regards
>
> Laurent
>

Hello,

yes, the current MFP code is adapted to a 68000 cpu and an MFP as found in 
an STF/STE.

Some factors should be applied when the cpu freq is different from 
8021247 Hz.

Nicolas