From alsa-devel-owner@alsa.jcu.cz  Tue Nov 17 14:56:53 1998
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	Tue, 17 Nov 1998 14:56:23 +0100
Date: Tue, 17 Nov 1998 14:56:23 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Stephane Conversy <conversy@lri.fr>
cc: alsa-devel@jcu.cz
Subject: Re: AC'97 question
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On Tue, 17 Nov 1998, Stephane Conversy wrote:

> Hello, again.
> 
> I'm trying to build a good configuration for my
> next linux machine, and browse the web for having
> the state of the art in the pc soundcards domain.
> 
> A week ago, i was wondering how to ask specs from
> manufacturers such as Aureal in order to develop
> an alsa driver.
> 
> But since those days, I have found another good
> cheap soundcard, an atrend harmony based on
> the YMF724 yamaha chip, which is ac'97 compliant.
> 
> I had a look to the available ac'97 specs, and how
> it was handled in alsa, and i saw there wasn't
> any file in the directory cards/.

OK. You probably don't understand what AC'97 stands for.
AC'97 is abbreviation for Audio Codec '97. Audio Codec
means that this chip have mixer and A/D and D/A converters
build in. AC'97 codecs doesn't communicate directly with
CPU, you need other chip which does bridge between PCI (or
some other bus). This chip also does things like sample 
transfers and conversions. You should look to specifications,
one in pdf version can be found at
	ftp://alsa.jcu.cz/pub/manuals/generic/ac97r21.pdf.

Alsa have implemented generic support for all AC'97 chips
in alsa-driver/lowlevel/generic/ac97_codec.c source file.
You need also documentation for chip which controls AC'97
codec (maybe AC'97 codec should be integrated to some
multifunctional chips).

Anyway - you need documentation for YMF724 chips. You cannot
do without this documentation driver.

					Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


