Re: [hatari-devel] IDE 32-bit data transfer

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 26/05/2016 à 18:49, Thomas Huth a écrit :

> Looking at the Falcon's schematics, only 16 out of the 32 data bus pins
> are connected at all, so on a plain Falcon, I think everything is 16
> bits only.
> For 32-bit Fast-RAM, you certainly needed an accelerator with a
> separate CPU, like the the Mighty Sonic or Afterburner040. (So in
> Hatari, I think we can assume 32-bit accesses for Falcon Fast-RAM,
> since you can't have memory above the 24-bit barrier on an unmodified
> Falcon anyway)

yes, in the case of the falcon, "fast ram" is not the correct term, 
because as you say you needed also another cpu to replace the 16 bit 
limited one of the falcon. Which means 2 cpu in the falcon in the end :)
(although the original one is in fact disabled). For those interested, 
the source of the CT60 card are available on the net, this gives lots of 
information on the changes needed.
In Hatari, we just add extra ram and mark it as 32 bit, but this also 
why we need to set address space to 32 bit, while a normal falcon 
doesn't require it.


> > So, before changing memory type, I'd like to unstack a few things I
> > have in progress :
> >   - wakeup states for STF (not related to this)
> >   - more accurate x2/x4 clock and cycle rounding (code is somewhat
> > complete but would conflict with some wakeup states changes, so can't
> > commit at the moment)
> >   - adapt memory type for each bank and measure/compare bus access
> > penalties in those cases (video access must be take into account to
> > round cpu accesses when necessary).
>
> Ok, thanks for sharing that information - and I'll keep my hands of
> that part now, so I don't interfere with your work ;-)

thanks :) In the end, it's quite likely we would come to the same 
results, but no need to duplicate work :)


Nicolas