see Sound

Registers

AUDC0 $15
AUDC1 $16

Stella

These addresses write data into the audio control registers which control the noise content and additional division of the audio output.

D3	D2	D1	D0	Type of noise or division
0	0	0	0	set to 1
0	0	0	1	4 bit poly
0	0	1	0	div 15 -> 4 bit poly
0	0	1	1	5 bit poly -> 4 bit poly
0	1	0	0	div 2 : pure tone
0	1	0	1	div 2 : pure tone
0	1	1	0	div 31 : pure tone
0	1	1	1	5 bit poly -> div 2
1	0	0	0	9 bit poly (white noise)
1	0	0	1	5 bit poly
1	0	1	0	div 31 : pure tone
1	0	1	1	set last 4 bits to 1
1	1	0	0	div 6 : pure tone
1	1	0	1	div 6 : pure tone
1	1	1	0	div 93 : pure tone
1	1	1	1	5 bit poly div 6