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Subject: RE: Reading from drive?
From: Nielsen Linus (ext) (Linus.Nielsen_at_elema.siemens.se)
Date: 2002-01-09


> Well... Won't re-engineering the code offer any clues?

Of course it will. Feel free to do it... :-)

> I mean, the research notes indicates that the MPEG outport
> port pins are known. Given that, the code has to use them
> to make sounds.

Yes. Via a 1mbit/s serial interface.

> To make sounds, it has to use mp3 data. To get the mp3 data
> it has to read the disk...

True again.

> Given that the CPU has DMA, we might get some details by
> checking out how the DMA is controlled and check the code
> for DMA activity (assuming they use DMA for at least some
> parts of the above).

The IDE seems to use plain parallel I/O. The serial line is
probably using some kind of DMA, or the CPU would not keep
up with the speed of data. Or it may have a huge FIFO
which is filled by the CPU once in a while.

> Or am I out in the blue again?

As always... :-)

/Linus



Page was last modified "Jan 10 2012" The Rockbox Crew
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