YM2612 Registers
0x22 - LFO
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | LFO Enable | LFO Frequency | |||||
| Value | LFO Frequency |
| 0 | 3.98 |
| 1 | 5.56 |
| 2 | 6.02 |
| 3 | 6.37 |
| 4 | 6.88 |
| 5 | 9.63 |
| 6 | 48.1 |
| 7 | 72.2 |
0x24/0x25 - Timer A
0x24
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Timer A (bit 10-2) | |||||||
0x25
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | Timer A (bit 1-0) | ||||||
0x26 - Timer B
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Timer B | |||||||
0x27 - Channel 3/6 and Timer control
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Channel 3 Mode
0 : Normal 1 : Special 2/3 : Illegal |
1 : Timer B Reset
0 : No effect | 1 : Timer A Reset
0 : No effect | 1 : Timer B overflow set the read register flag
0 : Timer B overflow don't set the read register flag | 1 : Timer A overflow set the read register flag
0 : Timer A overflow don't set the read register flag | 1 : Start Timer B
0 : Stop Timer B | 1 : Start Timer A
0 : Stop Timer A |
|
0x28 - Channel Operator control
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Operator | Unused | Channel | |||||
0x2A/0x2B - DAC
0x2A
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | DAC Data | |||||||
0x2B
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | 1 : DAC Enable
0 : DAC Disable |
Unused | ||||||
0x30-0x90 - Single operator control
Each channel operators is configured with 7 registers.
| Address | Part I | Part II |
| $x0 | Channel 1 Operator 1 | Channel 4 Operator 1 |
| $x1 | Channel 2 Operator 1 | Channel 5 Operator 1 |
| $x2 | Channel 3 Operator 1 | Channel 6 Operator 1 |
| $x4 | Channel 1 Operator 2 | Channel 4 Operator 2 |
| $x5 | Channel 2 Operator 2 | Channel 5 Operator 2 |
| $x6 | Channel 3 Operator 2 | Channel 6 Operator 2 |
| $x8 | Channel 1 Operator 3 | Channel 4 Operator 3 |
| $x9 | Channel 2 Operator 3 | Channel 5 Operator 3 |
| $xA | Channel 3 Operator 3 | Channel 6 Operator 3 |
| $xC | Channel 1 Operator 4 | Channel 4 Operator 4 |
| $xD | Channel 2 Operator 4 | Channel 5 Operator 4 |
| $xE | Channel 3 Operator 4 | Channel 6 Operator 4 |
0x3x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | DT1 (Detune) | MUL (Multiple) | |||||
MUL multiplies the overall frequency by it's value (except for the 0 value which multiply by 0.5)
DT1 gives small variations from the overall frequency x MUL.
| Value | Multiplicative effect |
| 0 | No change |
| 1 | x(1 + E) |
| 2 | x(1 + 2E) |
| 3 | x(1 + 3E) |
| 4 | No change |
| 5 | x(1 - E) |
| 6 | x(1 - 2E) |
| 7 | x(1 - 3E) |
0x4x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | Total level (envelope's highest amplitude) | ||||||
Value is between 0 (largest) and 127 (smallest)
A change of one unit is about 0.75dB
0x5x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | RS (Rate scaling) | Unused | AR (Attack rate) | |||||
0x6x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | AM (Amplitude modulation enable) | Unused | D1R (first decay rate) | |||||
0x7x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | D2R | ||||||
0x8x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | D1L | RR | ||||||
0x9x register
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | SSG-EG | ||||||
0xA0-0xB4 - Single channel control
Like the 0x30-0x90 range, each register is tripled.
| Address | Part I | Part II |
| $x0 | Channel 1 | Channel 4 |
| $x1 | Channel 2 | Channel 5 |
| $x2 | Channel 3 | Channel 6 |
0xAx - Frequency
The frequency is a 14-bit number, high part must be written in 0xA4 first, then lower part to 0xA0.
The three highest bit give the octave. The ten others give the position in the octave.
If channel 3 is in special mode (see register 0x27), one can control each channel 3 operators.
Operator 1 frequency is in 0xA2/0xA6. Operator 2 frequency is in 0xA8/0xAC. Operator 3 frequency is in 0xA9/0xAD. Operator 4 frequency is in 0xAA/0xAE.
0xB0 - Feedback and Algorithm
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Unused | Feedback | Algorithm | |||||
0xB4 - Stereo and LFO
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | Left | Right | AMS (Amplitude Modulation Sensitivity) | Unused | FMS (Frequency Modulation Sensitivity) | |||
| AMS Value | dB |
| 0 | 0 |
| 1 | 1.4 |
| 2 | 5.9 |
| 3 | 11.8 |
| FMS Value | % of a halftone |
| 0 | 0 |
| 1 | ~3.4 |
| 2 | ~6.7 |
| 3 | ~10 |
| 4 | ~14 |
| 5 | ~20 |
| 6 | ~40 |
| 7 | ~80 |