furnace/papers/doc/7-systems/arcade.md

1.1 KiB

Arcade (Yamaha YM2151/PCM)

this chip combination was used in the Sega OutRun, X and Y arcade boards, and perhaps a few others. the actual PCM chip had 16 channels, but the number has been cut to 5 in DefleMask for seemingly arbitrary reasons.

effects

  • 10xx: set noise frequency of channel 8 operator 4. 00 disables noise while 01 to 20 enables it.
  • 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: set LFO speed.
  • 18xx: set LFO waveform. xx may be one of the following:
    • 00: saw
    • 01: square
    • 02: triangle
    • 03: noise
  • 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.
  • 1Exx: set AM depth.
  • 1Fxx: set PM depth.
  • 20xx: set PCM frequency.
    • only works on the PCM channels.
    • xx is a 256th fraction of 31250Hz.