ASC/EASC audio device (take 2)

Please find the attached second incarnation of asc audio.

ftp://ftp.netbsd.org/pub/NetBSD/misc/nat/ascaudio-take2.diff

Interrupt routing has been fixed.

Interrupts are always used as they are always enabled for (non enhanced) ASCs.

At present playback works fine on my Powerbook 160 but I'm unsure as to how 
this will run on Macintosh SE/30s and and early Macintosh IIs due to the lower 
clock speed of the cpus in this these machines.

At present recording does not work (at least for me with the internal 
microphone) but it may work for you -  I'm very interested in 
feedback/possible solutions for this.

Play back works well, it supports 22khz stereo but I've found only 16khz mono 
files to play relatively stutter free.

Enjoy and please provide feeback on this version as I hope to add it (along 
with a manual page) soon.

Best regards,

Nat