Relations Between BPM Settings
--------------------------------
Final BPM = Tempo * 6 / Speed

Seconds per frame = 1 / Engine speed

Frames per row = 2.5 * Engine speed * Speed / Tempo

Seconds per row = 2.5 * Speed / Tempo

Default engine speed is 60 in NTSC mode and 50 in PAL mode.

Volume Chart
--------------
            Volume Column

   \|0 1 2 3 4 5 6 7 8 9 A B C D E F
   -+-------------------------------
   0|0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   1|0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
   2|0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2
   3|0 1 1 1 1 1 1 1 1 1 2 2 2 2 2 3
E  4|0 1 1 1 1 1 1 1 2 2 2 2 3 3 3 4
n  5|0 1 1 1 1 1 2 2 2 3 3 3 4 4 4 5
v  6|0 1 1 1 1 2 2 2 3 3 4 4 4 5 5 6
e  7|0 1 1 1 1 2 2 3 3 4 4 5 5 6 6 7
l  8|0 1 1 1 2 2 3 3 4 4 5 5 6 6 7 8
o  9|0 1 1 1 2 3 3 4 4 5 6 6 7 7 8 9
p  A|0 1 1 2 2 3 4 4 5 6 6 7 8 8 9 A
e  B|0 1 1 2 2 3 4 5 5 6 7 8 8 9 A B
   C|0 1 1 2 3 4 4 5 6 7 8 8 9 A B C
   D|0 1 1 2 3 4 5 6 6 7 8 9 A B C D
   E|0 1 1 2 3 4 5 6 7 8 9 A B C D E
   F|0 1 2 3 4 5 6 7 8 9 A B C D E F

Note: The Sawtooth wave has some glitches when the volume is acquired from the green bar.

NSF2MIDI volume scale
-----------------------
F: 127
E: 122
D: 118
C: 113
B: 108
A: 103
9: 98
8: 92
7: 86
6: 80
5: 73
4: 65
3: 56
2: 46
1: 32
0: 0

NSF2MIDI volume scale (FDS)
-----------------------------
32: 125
31: 123
30: 121
29: 119
28: 116
27: 114
26: 112
25: 110
24: 108
23: 106
22: 103
21: 101
20: 98
19: 96
18: 93
17: 91
16: 88
15: 85
14: 82
13: 79
12: 76
11: 73
10: 69
9: 66
8: 62
7: 58
6: 54
5: 49
4: 44
3: 38
2: 31
1: 22
0: 0

A0x Volume Fades Envelopes
----------------------------
Note: Assuming both envelope volume and column volume is 15 with 7xy effect not used.
A00: 15
A01: 15 15 15 15 15 15 15 14 14 14 14 14 14 14 14 13 13 13 13 13 13 13 13 12 12 12 12 12 12 12 12 11 11 11 11 11 11 11 11 10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 9 8 8 8 8 8 8 8 8 7 7 7 7 7 7 7 7 6 6 6 6 6 6 6 6 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 0
A02: 15 15 14 14 14 14 13 13 13 13 12 12 12 12 11 11 11 11 10 10 10 10 9 9 9 9 8 8 8 8 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 3 3 3 3 2 2 2 2 1 1 1 1 0
A03: 15 15 14 14 14 13 13 12 12 11 11 11 10 10 9 9 9 9 8 8 7 7 6 6 6 6 5 5 4 4 3 3 3 3 2 2 1 1 0
A04: 15 14 14 13 13 12 12 11 11 10 10 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0
A05: 15 14 14 13 12 12 11 10 10 9 9 8 7 7 6 5 5 4 4 3 2 2 1 0
A06: 15 14 13 12 12 11 10 9 9 8 7 6 6 5 4 3 3 2 1 0
A07: 15 14 13 12 11 10 9 8 8 7 6 5 4 3 2 1 1 0
A08: 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
A09: 14 13 12 11 10 9 8 6 5 4 3 2 1 0
A0A: 14 13 12 10 9 8 7 5 4 3 2 0
A0B: 14 13 11 10 9 7 6 4 3 2 0
A0C: 14 12 11 9 8 6 5 3 2 0
A0D: 14 12 11 9 7 6 4 2 1 0
A0E: 14 12 10 8 7 5 3 1 0
A0F: 14 12 10 8 6 4 2 0

For Ax0 volume fades, reverse the whole MML string, 0 to 15, 1 to 14, 2 to 13, etc.

4xy Vibrato Range
-------------------
4x0: 1 (2^0)
4x1: 1 (2^1-1)
4x2: 2 (2^1)
4x3: 3 (2^2-1)
4x4: 4 (2^2)
4x5: 7 (2^3-1)
4x6: 8 (2^3)
4x7: F (2^4-1)
4x8: 10 (2^4)
4x9: 1F (2^5-1)
4xA: 20 (2^5)
4xB: 3F (2^6-1)
4xC: 40 (2^6)
4xD: 7F (2^7-1)
4xE: 80 (2^7)
4xF: FF (2^8-1)
The vibrato effect always makes the pitch go up first, and then go down after reaching the maximum range.
Here is an ugly ASCII diagram:
     ^
     |
P +8 +         ......
i    |        .      .           etc.
t +4 +       .        .        .
c    |      .          .      .
h +0 +......            ......
     |
     +--+--+--+--+--+--+--+--+-->
        1  2  3  4  5  6  7  8
             Time elapsed

In 0.3.5 beta, another vibrato style is also offered:
     ^
     |
P +4 +  ....          ....
i    | .    .        .    .
t +0 +.      .      .      .
c    |        .    .        .
h -4 +         ....          ... etc.
     |
     +--+--+--+--+--+--+--+--+-->
        1  2  3  4  5  6  7  8
             Time elapsed

0.3.5 Beta:
4x0: 1
4x1: 3
4x2: 5
4x3: 7
4x4: 9
4x5: D
4x6: 13
4x7: 17
4x8: 1B
4x9: 21
4xA: 2B
4xB: 3B
4xC: 57
4xD: 7F
4xE: BF
4xF: FF

Key Frequency Registers
-------------------------
Note that with the release of FT 0.3.5 beta, most of them have been slightly modified.
A-0: 7F2
A#0: 77F
B-0: 714
C-1: 6AE
C#1: 64E
D-1: 5F3
D#1: 59E
E-1: 54D
F-1: 501
F#1: 4B9
G-1: 475
G#1: 435
A-1: 3F9
A#1: 3BF
B-1: 38A
C-2: 357
C#2: 327
D-2: 2F9
D#2: 2CF
E-2: 2A6
F-2: 280
F#2: 25C
G-2: 23A
G#2: 21A
A-2: 1FC
A#2: 1DF
B-2: 1C5
C-3: 1AB
C#3: 193
D-3: 17C
D#3: 167
E-3: 153
F-3: 140
F#3: 12E
G-3: 11D
G#3: 10D
A-3: FE
A#3: EF
B-3: E2
C-4: D5
C#4: C9
D-4: BE
D#4: B3
E-4: A9
F-4: A0
F#4: 97
G-4: 8E
G#4: 86
A-4: 7F
A#4: 77
B-4: 71
C-5: 6A
C#5: 64
D-5: 5F
D#5: 59
E-5: 54
F-5: 50
F#5: 4B
G-5: 47
G#5: 43
A-5: 3F
A#5: 3B
B-5: 38
C-6: 35
C#6: 32
D-6: 2F
D#6: 2C
E-6: 2A
F-6: 28
F#6: 25
G-6: 23
G#6: 21
A-6: 1F
A#6: 1D
B-6: 1C
C-7: 1A
C#7: 19
D-7: 17
D#7: 16
E-7: 15
F-7: 14
F#7: 12
G-7: 11
G#7: 10
A-7: F
A#7: E

Key Frequency * Key Frequency Register is always 111860.
Key Frequency Register is used for pitch changes. For example, a C-3 with fine pitch effect P(80+1AB-193)=P98 will give you a C#3, any key with pitch slide down effect 205 will INCREASE the frequency register by 5 per frame.
1 in the pitch bend sequence-graph INCREASES the frequency register by 1, -1 in the pitch bend sequence-graph DECREASES the frequency register by 1.

Differences of Adjacent Keys' Frequency Registers
---------------------------------------------------
A-0
    73
A#0
    6B
B-0
    66
C-1
    60
C#1
    5C
D-1
    55
D#1
    51
E-1
    4C
F-1
    48
F#1
    44
G-1
    40
G#1
    3C
A-1
    3A
A#1
    35
B-1
    33
C-2
    30
C#2
    2E
D-2
    2A
D#2
    29
E-2
    26
F-2
    24
F#2
    22
G-2
    20
G#2
    1E
A-2
    1D
A#2
    1A
B-2
    1A
C-3
    18
C#3
    17
D-3
    15
D#3
    14
E-3
    13
F-3
    12
F#3
    11
G-3
    10
G#3
    F
A-3
    F
A#3
    D
B-3
    C
C-4
    C
C#4
    B
D-4
    B
D#4
    A
E-4
    9
F-4
    9
F#4
    9
G-4
    8
G#4
    7
A-4
    8
A#4
    6
B-4
    7
C-5
    6
C#5
    5
D-5
    6
D#5
    5
E-5
    4
F-5
    5
F#5
    4
G-5
    4
G#5
    4
A-5
    4
A#5
    3
B-5
    3
C-6
    3
C#6
    3
D-6
    3
D#6
    2
E-6
    2
F-6
    3
F#6
    2
G-6
    2
G#6
    2
A-6
    2
A#6
    1
B-6
    2
C-7
    1
C#7
    2
D-7
    1
D#7
    1
E-7
    1
F-7
    2
F#7
    1
G-7
    1
G#7
    1
A-7
    1
A#7

Key Frequency Registers (Sawtooth)
------------------------------------
Note that with the release of FT 0.3.5 beta, most of them have been slightly modified.
C-0: F45
C#0: E6A
D-0: D9A
D#0: CD7
E-0: C1E
F-0: B70
F#0: ACC
G-0: A31
G#0: 99E
A-0: 914
A#0: 892
B-0: 816
C-1: 7A2
C#1: 735
D-1: 6CD
D#1: 66B
E-1: 60F
F-1: 5B8
F#1: 566
G-1: 518
G#1: 4CF
A-1: 48A
A#1: 449
B-1: 40B
C-2: 3D1
C#2: 39A
D-2: 366
D#2: 335
E-2: 307
F-2: 2DC
F#2: 2B3
G-2: 28C
G#2: 267
A-2: 245
A#2: 224
B-2: 205
C-3: 1E8
C#3: 1CD
D-3: 1B3
D#3: 19A
E-3: 183
F-3: 16E
F#3: 159
G-3: 146
G#3: 133
A-3: 122
A#3: 112
B-3: 102
C-4: F4
C#4: E6
D-4: D9
D#4: CD
E-4: C1
F-4: B7
F#4: AC
G-4: A3
G#4: 99
A-4: 91
A#4: 89
B-4: 81
C-5: 7A
C#5: 73
D-5: 6C
D#5: 66
E-5: 60
F-5: 5B
F#5: 56
G-5: 51
G#5: 4C
A-5: 48
A#5: 44
B-5: 40
C-6: 3D
C#6: 39
D-6: 36
D#6: 33
E-6: 30
F-6: 2D
F#6: 2B
G-6: 28
G#6: 26
A-6: 24
A#6: 22
B-6: 20
C-7: 1E
C#7: 1C
D-7: 1B
D#7: 19
E-7: 18
F-7: 16
F#7: 15
G-7: 14
G#7: 13
A-7: 12
A#7: 11
B-7: 10

Differences of Adjacent Keys' Frequency Registers (Sawtooth)
--------------------------------------------------------------
C-0
    DB
C#0
    D0
D-0
    C3
D#0
    B9
E-0
    AE
F-0
    A4
F#0
    9B
G-0
    92
G#0
    8A
A-0
    82
A#0
    7C
B-0
    74
C-1
    6D
C#1
    67
D-1
    62
D#1
    5C
E-1
    57
F-1
    52
F#1
    4E
G-1
    49
G#1
    45
A-1
    41
A#1
    3E
B-1
    3A
C-2
    37
C#2
    34
D-2
    31
D#2
    2E
E-2
    2B
F-2
    29
F#2
    27
G-2
    25
G#2
    22
A-2
    21
A#2
    1F
B-2
    1D
C-3
    1B
C#3
    1A
D-3
    19
D#3
    17
E-3
    15
F-3
    15
F#3
    13
G-3
    13
G#3
    11
A-3
    10
A#3
    10
B-3
    E
C-4
    E
C#4
    D
D-4
    C
D#4
    C
E-4
    A
F-4
    A
F#4
    9
G-4
    A
G#4
    8
A-4
    8
A#4
    8
B-4
    7
C-5
    7
C#5
    7
D-5
    6
D#5
    6
E-5
    5
F-5
    5
F#5
    5
G-5
    5
G#5
    4
A-5
    4
A#5
    4
B-5
    3
C-6
    5
C#6
    3
D-6
    3
D#6
    3
E-6
    3
F-6
    3
F#6
    2
G-6
    2
G#6
    2
A-6
    2
A#6
    2
B-6
    2
C-7
    2
C#7
    1
D-7
    2
D#7
    1
E-7
    2
F-7
    1
F#7
    1
G-7
    1
G#7
    1
A-7
    1
A#7
    1
B-7

Frequency Register (VRC7)
---------------------------
C: AC
C#: B5
D: C0
D#: CC
E: D8
F: E5
F#: F2
G: 101
G#: 110
A: 120
A#: 131
B: 143
The VRC7 chip uses two registers to define a pitch: key, octave.
3xx cancels all retriggers.
Qxx and Rxx don't work.

Note: VRC7 pitch slides are not working as expected and shall be modified in the future.
While using 1xx and 2xx, xx = 1 means 1/4 frequency register unit, xx = 4 means 1 frequency register unit.
1xx slides down and 2xx slides up.
While sliding across octaves, frequency registers are multiplied by 2^(octave change).
e.g.: Freuqncy register distance of sliding from B-3 to D-4 is (C0 * 2^(4-3) - 143) * 4 = F4.

Key Frequency Registers (FDS)
-------------------------------
C-0: 4C
C#0: 51
D-0: 56
D#0: 5B
E-0: 60
F-0: 66
F#0: 6C
G-0: 72
G#0: 79
A-0: 80
A#0: 88
B-0: 90
C-1: 99
C#1: A2
D-1: AC
D#1: B6
E-1: C1
F-1: CC
F#1: D8
G-1: E5
G#1: F3
A-1: 101
A#1: 111
B-1: 121
C-2: 132
C#2: 144
D-2: 158
D#2: 16C
E-2: 182
F-2: 199
F#2: 1B1
G-2: 1CE
G#2: 1E6
A-2: 203
A#2: 222
B-2: 242
C-3: 265
C#3: 289
D-3: 2B0
D#3: 2D9
E-3: 304
F-3: 332
F#3: 363
G-3: 396
G#3: 3CD
A-3: 407
A#3: 444
B-3: 485
C-4: 4CA
C#4: 513
D-4: 560
D#4: 5B2
E-4: 608
F-4: 664
F#4: 6C6
G-4: 72D
G#4: 79A
A-4: 80E
A#4: 888
B-4: 90A
C-5: 994
C#5: A26
D-5: AC0
D#5: B64
E-5: C11
F-5: CC9
F#5: D8C
G-5: E5A
G#5: F35
As command Pxx decreases the frequency register by (xx - 80), a lower xx gives a higher pitch.