>There seem to be two kinds of Sparc Audio.  The flavor used on the sun4c
>systems is pretty simple, but the one used on sun4m's like the SS10/20 uses
>the "DBRI" to drive the audio chip.  This is an AT&T ISDN driver chip of
>some complexity that happens to be able send a bit stream to/from the audio
>chip as one of it's tricks.  Getting docs for this chip out of AT&T and
>getting it to do something useful is a considerable challenge...notice there's
>no ISDN driver floating around either...  8-)

It's my understanding that the audio on the Sparc 5 is a _completely_
different beast, and actually uses a Crystal Semiconductor 4231 chip
(and maybe others).  It is definately a special case.

(I believe the reason that there's no ISDN driver is because the really
hard part is making it work with US ISDN equipment, since there are
a billion different standards.  We aren't lucky like our European friends).

--Ken