There is one person I know of for sure who has intimate knowledge of the
inner workings of the ASC (and all variants) - Antoine Rosset, the author
of Player Pro (the $100 shareware MOD/S3M/MADF etc. player for the Mac). 
He wrote an ASC direct driver for his MOD program in asm, and let me tell
you, it increases its performance on 68k Macs fourfold over Apple's
SoundManager.  Worked well on every 68k Mac that I tried it on.  Dunno how
helpful the guy would be, but you never know, and after all he isn't
Apple... 

http://www.quadmation.com
RossetAntoine@bluewin.ch

On Thu, 8 Jan 1998, Colin Wood wrote:

> Ok, I've got a favor to ask everyone.  I'm working on "sound" support for
> NetBSD.  This is motivated by the fact that my Quadra 700 only clicks for
> it's term bell, whereas my IIci actually beeps.  I'd like to be able to   
> get all Macs to the point where they can at least beep.  I'd really like  
> to be able to fully support /dev/audio, but that might require a minor    
> miracle (or a lot more staring at ROM code ;-)
>   
> Anyway, as part of this, I'd like to figure out how many truly different  
> kinds of sound hardware are out there.  The easiest way that I know of at
> the moment is to take a look at the control registers for the sound chip.
> The program I've attached below should do this.  If you can, please
> compile this program (I use "gcc -o sndctl sndctl.c"), run it, and email
> me the output from it (it should be about 0x50 lines, give or take a few).
> 
> Also, if you happen to have any _low_ level knowledge of Mac sound
> hardware, please let me know.  It appears that there is quite a difference
> between the ASC in the II-series Mac's and the EASC in my Q700.  I'm sure
> others will be just as different, but I'd like to support it all if
> possible.
> 
> So, I await your replies.
> 
> Thanks in advance!
> 
> --
> Colin Wood                                 cwood@ichips.intel.com
> Component Design Engineer - MD6                 Intel Corporation
> -----------------------------------------------------------------
> I speak only on my own behalf, not for my employer.