Re: sound blaster using DMA 0

Mike A. Harris (
Thu, 30 Jul 1998 03:31:22 -0400 (EDT)

On Wed, 29 Jul 1998, Matthew D. Pitts wrote:

> Kernel Hackers,
> AFAIK the newer SoundBlaster 32/64 cards are capable of full-duplex
> operation. Of course, I don't have one, or the docs for one.

Ok everybody, I'm getting a lot of postings of people repeating
themselves about the operation of the SoundBlaster series of

I will summarize:

1) The card in question is an official Creative SB16 Basic Edition
2) This card uses IRQ 5, DMA 1,5 for digital audio.
3) DMA 1 is 8 bit DMA
4) DMA 5 is 16 bit DMA

The DMA's and IRQ's are certainly configurable in hardware and
software, but that is what the settings are currently on my card.

5) There are 2 messages printing at startup upon sound init.
6) The first message is correct, the second is not.
7) MIDI does not use DMA at all, it isn't even an option
8) The display states that SB16 MIDI (0x330) is using DMA 0.

The display of that "DMA 0" is a bug. It does not mean "no dma",
it means "the routine that sets the parameters passed to the
conf_printf() routine doesn't set the dma and dma2 struct members
of hw_config to -1 indicating no dma. This amounts to it being
an uninitialized struct, or at least an improperly initialized

This has nothing to do with half duplex/full duplex, or the DSP
at all in any way.

I will post what I find soon...

Mike A. Harris  -  Computer Consultant  -  Linux advocate

Escape from the confines of Microsoft's operating systems and push your PC to it's limits with LINUX - a real OS.

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