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echo: os2prog
to: Richard Drapeau
from: Udo van den Heuvel
date: 1996-05-04 16:54:40
subject: DMA?

Hello Richard!

 UH>> OK, but how can I safely let the chips write to a buffer,
 UH>> somewhere below the 16 meg mark? How do I get a buffer below the 16
 UH>> meg mark? When I set up the DMA chips to write to a buffer, how does
 UH>> this work when another task is being serviced? Is the memory
 UH>> protection a problem? What other caveats are to be taken care of?
 UH>> (this is OS/2, not MS-DOS)
 RD>     I think the trick is to make a virtual device like Ray Gwinn's maked
 RD> for is SIO, for the communications ports

Yup! Just allocate a buffer of a multiple of 64K (256?) and just give the
devicedriver instructions what to do: pump data out or in at XX Khz.
When the program knows the 0:32 address of the buffer everything should be OK.

I do have source for MS-DOS but I'd like to be able to do all this in Warp.

Who can help me?

Greetz,
        Udo

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