mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-16 09:45:06 +00:00
101 lines
3.5 KiB
Markdown
101 lines
3.5 KiB
Markdown
# Yamaha YM2203 (OPN)
|
|
|
|
a cost-reduced version of the YM2151 (OPM).
|
|
it only has 3 FM channels instead of 8 and removes stereo, the LFO and DT2 (coarse detune).
|
|
|
|
however it does contain an AY/SSG part which provides 3 channels of square wave with noise and envelope.
|
|
|
|
this chip was used in the NEC PC-88/PC-98 series of computers, the Fujitsu FM-7AV and in some arcade boards.
|
|
|
|
several variants of this chip were released as well, with more features.
|
|
|
|
# effects
|
|
|
|
- `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.
|
|
- `18xx`: toggle extended channel 3 mode.
|
|
- 0 disables it and 1 enables it.
|
|
- only in extended channel 3 system.
|
|
- `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.
|
|
- `20xx`: set SSG channel mode. `xx` may be one of the following:
|
|
- `00`: square
|
|
- `01`: noise
|
|
- `02`: square and noise
|
|
- `03`: nothing (apparently)
|
|
- `04`: envelope and square
|
|
- `05`: envelope and noise
|
|
- `06`: envelope and square and noise
|
|
- `07`: nothing
|
|
- `21xx`: set noise frequency. `xx` is a value between 00 and 1F.
|
|
- `22xy`: set envelope mode.
|
|
- `x` sets the envelope shape, which may be one of the following:
|
|
- `0: \___` decay
|
|
- `4: /___` attack once
|
|
- `8: \\\\` saw
|
|
- `9: \___` decay
|
|
- `A: \/\/` inverse obelisco
|
|
- `B: \¯¯¯` decay once
|
|
- `C: ////` inverse saw
|
|
- `D: /¯¯¯` attack
|
|
- `E: /\/\` obelisco
|
|
- `F: /___` attack once
|
|
- if `y` is 1 then the envelope will affect this channel.
|
|
- `23xx`: set envelope period low byte.
|
|
- `24xx`: set envelope period high byte.
|
|
- `25xx`: slide envelope period up.
|
|
- `26xx`: slide envelope period down.
|
|
- `29xy`: enable SSG auto-envelope mode.
|
|
- in this mode the envelope period is set to the channel's notes, multiplied by a fraction.
|
|
- `x` is the numerator.
|
|
- `y` is the denominator.
|
|
- if `x` or `y` are 0 this will disable auto-envelope mode.
|
|
- `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: +0
|
|
- 1: +1
|
|
- 2: +2
|
|
- 3: +3
|
|
- 4: -0
|
|
- 5: -3
|
|
- 6: -2
|
|
- 7: -1
|
|
- `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.
|