Pulse Channel frequency chart

MIDI Tuning Table

Using the MIDI Tuning Standard with A=440 Hz, we can derive the equivalent period timer value for the two Pulse channels. Due to limitations on the 11-bit period’s range, the lowest standard MIDI frequency that can be reproduced with acceptable tuning is A-1 (55 Hz) on NTSC, and G#1 (51.91 Hz) on PAL. Here we show the desired frequency for each MIDI index, the closest period value, and the resulting tuning error (in cents) from the standard.

Note: The Triangle channel can make use of the same 11-bit period values. Due to its longer 32-step sequence, it will sound exactly one octave lower (half of the apparent frequency) compared to the equivalent period on Pulse.

MIDI			NTSC APU Pulse			PAL APU Pulse
Index	Note	Frequency	11bit Period	Frequency	Tuning	11bit Period	Frequency	Tuning
31	G-1	49.00	-	-	-	$7FF	50.74	+60c
32	G#1	51.91	$7FF	54.62	+88c	$7D1	51.90	+0c
33	A-1	55.00	$7F1	55.00	+0c	$760	55.01	+0c
34	A#1	58.27	$77F	58.26	+0c	$6F6	58.28	+0c
35	B-1	61.74	$713	61.73	+0c	$692	61.74	+0c
36	C-2	65.41	$6AD	65.42	+0c	$634	65.40	+0c
37	C#2	69.30	$64D	69.31	+0c	$5DB	69.28	-1c
38	D-2	73.42	$5F3	73.40	+0c	$586	73.44	+0c
39	D#2	77.78	$59D	77.79	+0c	$537	77.78	+0c
40	E-2	82.41	$54C	82.43	+1c	$4EC	82.41	+0c
41	F-2	87.31	$500	87.32	+0c	$4A5	87.32	+0c
42	F#2	92.50	$4B8	92.52	+0c	$462	92.53	+1c
43	G-2	98.00	$474	98.04	+1c	$423	98.03	+1c
44	G#2	103.83	$434	103.86	+1c	$3E8	103.81	+0c
45	A-2	110.00	$3F8	109.99	+0c	$3B0	109.96	-1c
46	A#2	116.54	$3BF	116.52	+0c	$37B	116.49	-1c
47	B-2	123.47	$389	123.47	+0c	$349	123.41	-1c
48	C-3	130.81	$356	130.83	+0c	$319	130.87	+1c
49	C#3	138.59	$326	138.61	+0c	$2ED	138.55	-1c
50	D-3	146.83	$2F9	146.80	+0c	$2C3	146.77	-1c
51	D#3	155.56	$2CE	155.58	+0c	$29B	155.56	+0c
52	E-3	164.81	$2A6	164.74	-1c	$275	164.94	+1c
53	F-3	174.61	$280	174.51	-1c	$252	174.64	+0c
54	F#3	185.00	$25C	184.89	-1c	$231	184.90	-1c
55	G-3	196.00	$23A	195.90	-1c	$211	196.06	+1c
56	G#3	207.65	$21A	207.53	-1c	$1F3	207.83	+1c
57	A-3	220.00	$1FB	220.20	+2c	$1D7	220.15	+1c
58	A#3	233.08	$1DF	233.04	+0c	$1BD	232.99	-1c
59	B-3	246.94	$1C4	246.93	+0c	$1A4	246.82	-1c
60	C-4	261.63	$1AB	261.36	-2c	$18C	261.75	+1c
61	C#4	277.18	$193	276.88	-2c	$176	277.10	-1c
62	D-4	293.66	$17C	293.60	+0c	$161	293.54	-1c
63	D#4	311.13	$167	310.72	-2c	$14D	311.12	+0c
64	E-4	329.63	$152	329.97	+2c	$13A	329.88	+1c
65	F-4	349.23	$13F	349.57	+2c	$129	348.70	-3c
66	F#4	369.99	$12D	370.40	+2c	$118	369.80	-1c
67	G-4	392.00	$11C	392.49	+2c	$108	392.12	+1c
68	G#4	415.30	$10C	415.84	+2c	$0F9	415.65	+1c
69	A-4	440.00	$0FD	440.40	+2c	$0EB	440.31	+1c
70	A#4	466.16	$0EF	466.09	+0c	$0DE	465.98	-1c
71	B-4	493.88	$0E1	494.96	+4c	$0D1	494.82	+3c
72	C-5	523.25	$0D5	522.71	-2c	$0C6	522.18	-4c
73	C#5	554.37	$0C9	553.77	-2c	$0BA	555.68	+4c
74	D-5	587.33	$0BD	588.74	+4c	$0B0	587.08	-1c
75	D#5	622.25	$0B3	621.45	-2c	$0A6	622.23	+0c
76	E-5	659.26	$0A9	658.00	-3c	$09D	657.68	-4c
77	F-5	698.46	$09F	699.13	+2c	$094	697.40	-3c
78	F#5	739.99	$096	740.80	+2c	$08B	742.24	+5c
79	G-5	783.99	$08E	782.24	-4c	$084	781.30	-6c
80	G#5	830.61	$086	828.60	-4c	$07C	831.30	+1c
81	A-5	880.00	$07E	880.79	+2c	$075	880.62	+1c
82	A#5	932.33	$077	932.17	+0c	$06E	936.15	+7c
83	B-5	987.77	$070	989.92	+4c	$068	989.65	+3c
84	C-6	1046.50	$06A	1045.43	-2c	$062	1049.63	+5c
85	C#6	1108.73	$064	1107.53	-2c	$05D	1105.46	-5c
86	D-6	1174.66	$05E	1177.48	+4c	$057	1180.83	+9c
87	D#6	1244.51	$059	1242.90	-2c	$052	1251.96	+10c
88	E-6	1318.51	$054	1316.01	-3c	$04E	1315.35	-4c
89	F-6	1396.91	$04F	1398.26	+2c	$049	1404.23	+9c
90	F#6	1479.98	$04B	1471.85	-10c	$045	1484.47	+5c
91	G-6	1567.98	$046	1575.50	+8c	$041	1574.44	+7c
92	G#6	1661.22	$042	1669.56	+9c	$03E	1649.41	-12c
93	A-6	1760.00	$03F	1747.83	-12c	$03A	1761.24	+1c
94	A#6	1864.66	$03B	1864.35	+0c	$037	1855.59	-8c
95	B-6	1975.53	$038	1962.47	-11c	$034	1960.62	-13c
96	C-7	2093.00	$034	2110.58	+14c	$031	2078.26	-12c
97	C#7	2217.46	$031	2237.22	+15c	$02E	2210.91	-5c
98	D-7	2349.32	$02F	2330.43	-14c	$02B	2361.66	+9c
99	D#7	2489.02	$02C	2485.80	-2c	$029	2474.12	-10c
100	E-7	2637.02	$029	2663.35	+17c	$026	2664.43	+18c
101	F-7	2793.83	$027	2796.52	+2c	$024	2808.46	+9c
102	F#7	2959.96	$025	2943.71	-10c	$022	2968.94	+5c
103	G-7	3135.96	$023	3107.24	-16c	$020	3148.88	+7c
104	G#7	3322.44	$021	3290.02	-17c	$01E	3352.03	+15c
105	A-7	3520.00	$01F	3495.65	-12c	$01D	3463.76	-28c
106	A#7	3729.31	$01D	3728.69	+0c	$01B	3711.18	-8c
107	B-7	3951.07	$01B	3995.03	+19c	$019	3996.65	+20c
108	C-8	4186.01	$01A	4142.99	-18c	$018	4156.52	-12c
109	C#8	4434.92	$018	4474.43	+15c	$016	4517.95	+32c
110	D-8	4698.64	$017	4660.87	-14c	$015	4723.32	+9c
111	D#8	4978.03	$015	5084.58	+37c	$014	4948.24	-10c
112	E-8	5274.04	$014	5326.71	+17c	$013	5195.65	-26c
113	F-8	5587.65	$013	5593.04	+2c	$012	5469.10	-37c
114	F#8	5919.91	$012	5887.41	-10c	$011	5772.94	-44c
115	G-8	6271.93	$011	6214.49	-16c	$010	6112.53	-45c
116	G#8	6644.88	$010	6580.05	-17c	$00F	6494.56	-40c
117	A-8	7040.00	$00F	6991.30	-12c	$00E	6927.53	-28c
118	A#8	7458.62	$00E	7457.39	+0c	$00D	7422.35	-8c
119	B-8	7902.13	$00D	7990.06	+19c	$00C	7993.30	+20c
120	C-9	8372.02	$00C	8604.68	+47c	$00B	8659.41	+58c
121	C#9	8869.84	$00C	8604.68	-53c	$00B	8659.41	-42c
122	D-9	9397.27	$00B	9321.73	-14c	$00A	9446.63	+9c
123	D#9	9956.06	$00A	10169.16	+37c	$009	10391.29	+74c
124	E-9	10548.08	$00A	10169.16	-63c	$009	10391.29	-26c
125	F-9	11175.30	$009	11186.08	+2c	$008	11545.88	+56c
126	F#9	11839.82	$008	12428.98	+84c	$008	11545.88	-44c
127	G-9	12543.85	$008	12428.98	-16c	-	-	-

Code Friendly Tables

Here are the period values from the above table in ca65 syntax, split into low/high byte halves for convenient indexing.

Note: These include every MIDI index from 0-127. This means the first ~32 entries in the table contain nonsense values, as the equivalent periods are larger than the range of the 11-bit timer. Programmers may wish to trim these early entries to save space.

NTSC Periods

ntsc_period_low:
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $f1, $7f, $13, $ad, $4d, $f3, $9d
  .byte $4c, $00, $b8, $74, $34, $f8, $bf, $89
  .byte $56, $26, $f9, $ce, $a6, $80, $5c, $3a
  .byte $1a, $fb, $df, $c4, $ab, $93, $7c, $67
  .byte $52, $3f, $2d, $1c, $0c, $fd, $ef, $e1
  .byte $d5, $c9, $bd, $b3, $a9, $9f, $96, $8e
  .byte $86, $7e, $77, $70, $6a, $64, $5e, $59
  .byte $54, $4f, $4b, $46, $42, $3f, $3b, $38
  .byte $34, $31, $2f, $2c, $29, $27, $25, $23
  .byte $21, $1f, $1d, $1b, $1a, $18, $17, $15
  .byte $14, $13, $12, $11, $10, $0f, $0e, $0d
  .byte $0c, $0c, $0b, $0a, $0a, $09, $08, $08

ntsc_period_high:
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $06, $06, $05, $05
  .byte $05, $05, $04, $04, $04, $03, $03, $03
  .byte $03, $03, $02, $02, $02, $02, $02, $02
  .byte $02, $01, $01, $01, $01, $01, $01, $01
  .byte $01, $01, $01, $01, $01, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00

PAL Periods

pal_period_low:
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $ff, $ff, $ff, $ff, $ff, $ff, $ff, $ff
  .byte $d1, $60, $f6, $92, $34, $db, $86, $37
  .byte $ec, $a5, $62, $23, $e8, $b0, $7b, $49
  .byte $19, $ed, $c3, $9b, $75, $52, $31, $11
  .byte $f3, $d7, $bd, $a4, $8c, $76, $61, $4d
  .byte $3a, $29, $18, $08, $f9, $eb, $de, $d1
  .byte $c6, $ba, $b0, $a6, $9d, $94, $8b, $84
  .byte $7c, $75, $6e, $68, $62, $5d, $57, $52
  .byte $4e, $49, $45, $41, $3e, $3a, $37, $34
  .byte $31, $2e, $2b, $29, $26, $24, $22, $20
  .byte $1e, $1d, $1b, $19, $18, $16, $15, $14
  .byte $13, $12, $11, $10, $0f, $0e, $0d, $0c
  .byte $0b, $0b, $0a, $09, $09, $08, $08, $07

pal_period_high:
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $07, $07, $07, $07, $07, $07
  .byte $07, $07, $06, $06, $06, $05, $05, $05
  .byte $04, $04, $04, $04, $03, $03, $03, $03
  .byte $03, $02, $02, $02, $02, $02, $02, $02
  .byte $01, $01, $01, $01, $01, $01, $01, $01
  .byte $01, $01, $01, $01, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00
  .byte $00, $00, $00, $00, $00, $00, $00, $00

V \| T APU
Concepts	Registers \| Basics \| Period table
Channels	Pulse 1 and Pulse 2 \| Triangle \| Noise \| DMC
Components	Envelope \| Sweep \| Frame Counter \| Length Counter \| DMA \| Mixer
Expansion audio	2C33 (Disk System) \| MMC5 \| VRC6 \| VRC7 \| Namco 163 \| Sunsoft 5B \| µPD7756

Pulse Channel frequency chart

MIDI Tuning Table

Code Friendly Tables

NTSC Periods

PAL Periods

See also