Re: [hatari-devel] TT mono mode Timer-C problem

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

Using the CPU as the main clock is OK for me (but it means that the CPU 
must be perfectly (or nearly perfectly)  cycle accurate).

The problem with the 8Mhz frequency is for the TT.

Some instructions are taking 2 cycles to execute (when in the cache).

2 cycles/4 = 0 cycles, which may result to strange results (as the main 
clock is the cpu clock).

But let's see this later.

Regards

Laurent




One of the problems of this techn
Le 17/12/2011 18:53, Nicolas Pomarède a écrit :
> On 17/12/2011 10:35, Nicolas Pomarède wrote:
> > Hello
> >
> > yes, it's a known limitation that at the moment the interrupt events are
> > expecting the cpu clock to be 8 MHz. If you use 16 or 32 MHz, interrupts
> > won't be good.
> > This will be fixed some day, as it can also impact falcon mode, but for
> > now all the interrupts events are "locked" to the cpu freq (instead of
> > the master bus freq on a real ST/TT/Falcon)
>
> Hmm, I replied too quickly. Hatari will always emulate an 8 MHz cpu 
> clock, cpu freq is simulted by dividing cpu cycles by 2 or 4.
>
> So the MFP timers are always good when you change cpu speed (you can 
> check this with tos 1.04, your program runs fine in color or mono, 
> with 8/16/32 cpu freq).
>
> It seems emutos computes $4ba in a different way in mono mode, maybe 
> it doesn't use the same 200 Hz timer as in color ?
>
> Nicolas