furnace/papers/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.

For 0.6pre1, Furnace can now support advanced YM2612 features that Fractal sound driver adds: two software-mixed PCM channels (variable pitch, sample offsets, max 13.7 khz rate) and CSM - ch3 special mode feature that can be abused to produce rudimentary speech synthesis.

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 mutliplier.
• 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.