furnace/doc/7-systems/ym2612.md

# Yamaha YM2612

one of two chips that powered the Sega Genesis. It is a six-channel, four-operator FM synthesizer. Channel #6 can be turned into 8-bit PCM player, that via software mixing, thanks to Z80 sound CPU, can play more than one channel of straight-shot samples at once. As of Furnace 0.6pre5, Furnace offers DualPCM, which allows 2 channels of software-mixed 8-bit PCM samples at 13750 Hz.

# effects

- **`10xy`**: set LFO parameters.
  - `x` toggles the LFO.
  - `y` sets its speed.
- **`11xx`**: set feedback of channel.
- **`12xx`**: set operator 1 level.
- **`13xx`**: set operator 2 level.
- **`14xx`**: set operator 3 level.
- **`15xx`**: set operator 4 level.
- **`16xy`**: set multiplier of operator.
  - `x` is the operator (1-4).
  - `y` is the multiplier.
- **`17xx`**: enable PCM channel.
  - this only works on channel 6.
- **`18xx`**: toggle extended channel 3 mode.
  - 0 disables it and 1 enables it.
  - only in extended channel 3 chip.
- **`19xx`**: set attack of all operators.
- **`1Axx`**: set attack of operator 1.
- **`1Bxx`**: set attack of operator 2.
- **`1Cxx`**: set attack of operator 3.
- **`1Dxx`**: set attack of operator 4.
- **`30xx`**: enable envelope hard reset.
  - this works by inserting a quick release and tiny delay before a new note.
- **`50xy`**: set AM of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` determines whether AM is on.
- **`51xy`**: set SL of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` is the value.
- **`52xy`**: set RR of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` is the value.
- **`53xy`**: set DT of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` is the value:
    - 0: -3
    - 1: -2
    - 2: -1
    - 3: 0
    - 4: 1
    - 5: 2
    - 6: 3
    - 7: -0
- **`54xy`**: set RS of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` is the value.
- **`55xy`**: set SSG-EG of operator.
  - `x` is the operator (1-4). a value of 0 means "all operators".
  - `y` is the value (0-8).
    - values between 0 and 7 set SSG-EG.
    - value 8 disables it.
- **`56xx`**: set DR of all operators.
- **`57xx`**: set DR of operator 1.
- **`58xx`**: set DR of operator 2.
- **`59xx`**: set DR of operator 3.
- **`5Axx`**: set DR of operator 4.
- **`5Bxx`**: set D2R/SR of all operators.
- **`5Cxx`**: set D2R/SR of operator 1.
- **`5Dxx`**: set D2R/SR of operator 2.
- **`5Exx`**: set D2R/SR of operator 3.
- **`5Fxx`**: set D2R/SR of operator 4.