furnace/doc/7-systems/genesis.md

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 and a derivative of the SN76489.

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 there 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.