Re: [hatari-devel] STe DMA sound

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On 15/04/2018 at 08:33, Vincent Rivière wrote:
With proper traces in YM emulation, I guess we could understand why that
tune plays...

After having added some traces...

If I'm not mistaken, the 7 KHz artifact appears when Lethal Xcess sets the period of voice C to 0 (by writing 0 to YM registers 4 and 5), while keeping the voice enabled (register 7). This might be a Lethal Xcess bug. AFAIK, such mode should only be enabled to play samples. Maybe some leftover of ST digidrums.
I'm not sure what is supposed to happen on real ST in that case.

In sound.c, function Sound_WriteReg().
I cases 4 and 5:
As a test, I forced "ToneC_per = 0;".
In that case, the music disappears, but the high-pitched artifact remains!
So the issue is definitely somewhere near that place.

Finally, I'm not sure if there is really a problem with STe DMA...
But with the lack of YM digidrums on STe, certainly.

I'm sorry, the problems goes beyond my understanding of Hatari code, and I have no more time...
But I'm sure we are now looking to the right direction.

Vincent Rivière

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