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30 lines
1.1 KiB
Markdown
30 lines
1.1 KiB
Markdown
# Arcade (Yamaha YM2151/PCM)
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this chip combination was used in the Sega OutRun, X and Y arcade boards, and perhaps a few others.
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the actual PCM chip had 16 channels, but the number has been cut to 5 in DefleMask for seemingly arbitrary reasons. a system with all 16 channels may be coming soon.
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# effects
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- `10xx`: set noise frequency of channel 8 operator 4. 00 disables noise while 01 to 20 enables it.
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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 mutliplier.
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- `17xx`: set LFO speed.
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- `18xx`: set LFO waveform. `xx` may be one of the following:
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- `00`: saw
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- `01`: square
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- `02`: triangle
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- `03`: noise
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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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- `20xx`: set PCM frequency.
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- only works on the PCM channels.
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- `xx` is a 256th fraction of 31250Hz.
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