Re: [hatari-devel] Re: 040/060 emulation issue with BadMood

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 03/03/2015 16:05, Douglas Little a écrit :
> So after poking around with the new Hatari in 060 mode, I did find a
> bunch of oversights and timing gaps in my code - so these have all been
> fixed. It now runs in Hatari in 060 mode.
>
> However based on tests with real HW, it seems Hatari is somehow
> outracing real CT60s on the CPU/bus side, leaving the DSP in the dust.
> Probably to be expected - but I had to set up the sync sites to be
> extra-pedantic in a way that didn't seem necessary, at least up to 75MHz
> on a CT60.
>
> Beyond 75MHz, maybe things start to equalize with Hatari.
>
> This isn't a bug report - just some extra context for comparison with
> CT60 timing in case anyone finds it useful..

Hi

although 68060 and 68040 share nearly common instructions set, the 68060 
has some much more advanced pipeline and others which makes it faster 
than a 68040 at the same freq.

In Hatari (and WinUAE), this speed difference is handled by assuming all 
instructions will take only 1 cycle in 68060 mode ; this is of course 
not correct and will be noticeable when you try to sync with the DSP 
where timings matter.

Nicolas