# Sega Genesis/Mega Drive

a video game console that showed itself as the first true rival to Nintendo's video game market near-monopoly in the US during the '80's.

this console is powered by two sound chips: the [Yamaha YM2612](ym2612.md) and [a derivative of the SN76489](sms.md).

# 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.
  - _this effect is here for compatibility reasons!_ it is otherwise recommended to use Sample type instruments (which automatically enable PCM mode when used).
- `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.**
- `20xy`: **set PSG noise mode.**
  - `x` controls whether to inherit frequency from PSG channel 3.
    - `0`: use one of 3 preset frequencies (C: A-2; C#: A-3; D: A-4).
    - `1`: use frequency of PSG channel 3.
  - `y` controls whether to select noise or thin pulse.
    - `0`: thin pulse.
    - `1`: noise.