To hear from BASIC, just load ,8,1, sys 7168 to init, and poke 54296,15 to turn on the volume. Then poke 7193 with a number from 0 to 10 to listen to an effect.
Remember, this program was written for a specific application. In the particular application there is a tune playing, which is why fx doesn't set the volume register (and why it uses voice 3), for example.
Files:
Stephen L. Judd