69 lines
2.8 KiB
Markdown
69 lines
2.8 KiB
Markdown
# Yamaha YM2612
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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, that via software mixing, thanks to Z80 sound CPU, can play more than one channel of straight-shot samples at once.
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as of Furnace 0.6pre5, Furnace offers DualPCM, Z80 driver that splits channel 6 into two individual PCM channels with variable pitch. using the console's Z80 processor, these are mixed together in software and streamed to channel 6 in PCM mode with a mix rate of 13750 Hz. because this generates a stream of data, exported VGM files will be very large.
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# effects
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- `10xy`: **set LFO parameters.**
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- `x` toggles the LFO.
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- `y` sets its speed.
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- `11xx`: **set feedback of channel.**
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- `12xx`: **set operator 1 level.**
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- `13xx`: **set operator 2 level.**
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- `14xx`: **set operator 3 level.**
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- `15xx`: **set operator 4 level.**
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- `16xy`: **set multiplier of operator.**
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- `x` is the operator (1-4).
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- `y` is the multiplier.
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- `17xx`: **enable PCM channel.**
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- this only works on channel 6.
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- `18xx`: **toggle extended channel 3 mode.**
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- 0 disables it and 1 enables it.
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- only in extended channel 3 chip.
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- `19xx`: **set attack of all operators.**
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- `1Axx`: **set attack of operator 1.**
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- `1Bxx`: **set attack of operator 2.**
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- `1Cxx`: **set attack of operator 3.**
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- `1Dxx`: **set attack of operator 4.**
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- `30xx`: **enable envelope hard reset.**
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- this works by inserting a quick release and tiny delay before a new note.
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- `50xy`: **set AM of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` determines whether AM is on.
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- `51xy`: **set SL of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` is the value.
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- `52xy`: **set RR of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` is the value.
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- `53xy`: **set DT of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` is the value:
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- `0`: -3
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- `1`: -2
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- `2`: -1
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- `3`: 0
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- `4`: 1
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- `5`: 2
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- `6`: 3
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- `7`: -0
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- `54xy`: **set RS of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` is the value.
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- `55xy`: **set SSG-EG of operator.**
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- `x` is the operator (1-4). a value of 0 means "all operators".
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- `y` is the value (0-8).
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- values between 0 and 7 set SSG-EG.
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- value 8 disables it.
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- `56xx`: **set DR of all operators.**
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- `57xx`: **set DR of operator 1.**
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- `58xx`: **set DR of operator 2.**
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- `59xx`: **set DR of operator 3.**
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- `5Axx`: **set DR of operator 4.**
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- `5Bxx`: **set D2R/SR of all operators.**
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- `5Cxx`: **set D2R/SR of operator 1.**
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- `5Dxx`: **set D2R/SR of operator 2.**
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- `5Exx`: **set D2R/SR of operator 3.**
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- `5Fxx`: **set D2R/SR of operator 4.**
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