Re: [hatari-devel] 2 more falcon demos running with the new core

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On Wednesday 18 January 2012 10:54, Laurent Sallafranque wrote:
> Hi,
> While testing, 2 more demos appear to run better with the latest WINUAE
> core and the latest timings.
> - dementia by Aura : it works until the end (I've verified 100 000 lines
> of traces, DSP and CPU are perfectly in sync in this demo).


I looked at the Falcon schematics because of the latest conversations.
I also took at quick look at Hatari's videl, dsp and crossbar code to
get some background on the topic.

Here are a few of my observations:

It appears that the dsp56000 communicates with the rest of the computer
(host) with handshakes, interrupts and DMA. The dsp clock is connected
to the 56000 and DMA only. Thus the 56000 is independent of the host,
and uses buffered communication (latched, fifo'd, DMA'd) for host

dsp   clock: 32 MHz  (dsp frequency is less than a multiple of the cpu)
videl clock: 25.175 MHz

Choose North American OR European Falcon:
NTSC  clock: 32.215905 MHz (ntsc cpu freq = 32.215905/2 MHz)
PAL   clock: 32.084988 MHz (pal  cpu freq = 32.084988/2 MHz) (peritel SCART)


> The sound is low (8 bit DMA stereo may be the problem to look at)
> - Fried bits #3 Thing demo by Aura and Digital Chaos : this one never
> run after the first black and white screen.
> Now it runs the 5 first effects.
> The nemaining problems :
> - Sound is OK, except during the 2nd effect (probably related to big
> cycle instructions), because just after this effect, the music becomes
> perfect again.
> - the first effect (a coloured tunnel) is displayed strangely (Videl issue)
> - the demo freezes after the 4th effect (black screen). Probably DSP/CPU
> Timings problems.
> I'll play with it to try to solve some problems.
> Regards
> Laurent

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