AtariWiki V3.1: AUDF4

Read/Write	ADR	HEXADR	NAME	Description	shadow	OS
Read	53766	$D206	POT6	Pot/paddle 6	630	all
Write	53766	$D206	AUDF4	Audio channel 4 frequency	none	all

Reads the value of pot (paddle) 6.

Frequency of Audio channel 4. This value can be between 0 ($00) and 255 ($FF), where 0 is the highest tone/pitch and 255 is the lowest tone/pitch.

With a base frequency of 64kHz, distortion=10 and A3=443Hz the following values define the respective notes for PAL-ATARIs

Oktave	C	#C	D	#D	E	F	#F	G	#G	A	#A	H
2	239	226	213	201	190	179	169	159	150	142	134	126
3	119	112	106	100	94	89	84	79	75	70	66	63
4	59	56	53	50	47	44	42	39	37	35	33	31
5	29	27	26	24	23	22	20	19	18	17	16	15
6	14	13	(12)	(12)	11	10		9		8		7

For NTSC-ATARIs use the following values defining the respective notes (distortion=10, A3=443Hz)

Oktave	C	#C	D	#D	E	F	#F	G	#G	A	#A	H
2	243	230	217	204	193	182	173	162	153	144	136	128
3	121	114	108	102	96	91	85	81	76	72	68	64
4	60	57	53	50	47	45	42	40	37	35	33	31
5	29	27	26	24	23	22	20	19	18	17	16	15

Use AUDC4 to set distortion and volume for channel 4.

Oktave	C	#C	D	#D	E	F	#F	G	#G	A	#A	H
2	243	230	217	204	193	182	173	162	153	144	136	128
3	121	114	108	102	96	91	85	81	76	72	68	64
4	60	57	53	50	47	45	42	40	37	35	33	31
5	29	27	26	24	23	22	20	19	18	17	16	15

Oktave	C	#C	D	#D	E	F	#F	G	#G	A	#A	H
2	243	230	217	204	193	182	173	162	153	144	136	128
3	121	114	108	102	96	91	85	81	76	72	68	64
4	60	57	53	50	47	45	42	40	37	35	33	31
5	29	27	26	24	23	22	20	19	18	17	16	15

Oktave	C	#C	D	#D	E	F	#F	G	#G	A	#A	H
2	243	230	217	204	193	182	173	162	153	144	136	128
3	121	114	108	102	96	91	85	81	76	72	68	64
4	60	57	53	50	47	45	42	40	37	35	33	31
5	29	27	26	24	23	22	20	19	18	17	16	15