41 lines
2 KiB
Markdown
41 lines
2 KiB
Markdown
# OKI MSM5232
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a rather primitive (but powerful) sound generator chip used in some arcade boards and even synthesizers (like Korg Poly-800).
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it has 8 channels in 2 groups (of 4 channels each). each group can be configured with an envelope and the ability to produce 2', 4', 8' and/or 16' square/noise overtones on 8 outputs (four (2', 4', 8' and 16') per group).
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however, this chip cannot entirely produce sound alone. it has to be paired with either an external envelope generator or capacitors to assist the internal envelope generator.
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it also has no fine tune whatsoever. the frequency resolution is exactly a semitone.
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Furnace implements this chip in a way that allows the following features:
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- internal (capacitors) or external (volume macro) envelope modes per group
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- the ability to change the volume of each output (this can be used to generate saw waves if you set each part/overtone's volume to exactly half of the previous one)
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- global fine tune
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- global vibrato (some arcade boards played with the clock input to simulate vibrato)
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## effects
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- `10xy`: **set group control.**
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- `x` sets sustain mode.
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- `y` is a 4-bit mask which toggles overtones.
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- `11xx`: **set noise mode.**
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- `12xx`: **set group attack.** range is `0` to `5`.
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- only in internal (capacitor-based) envelope mode.
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- `13xx`: **set group decay.** range is `0` to `11`.
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- only in internal (capacitor-based) envelope mode.
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## info
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this chip uses the [MSM5232](../4-instrument/msm5232.md) instrument editor.
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## chip config
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the following options are available in the Chip Manager window:
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- **Detune**: sets detune in 128ths of a semitone.
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- **Capacitor values**: allows you to change the capacitance of the 8 capacitors connected to the chip. longer values increase envelope length.
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- **Initial part volume**: sets the initial volume of each "part" (octave) in a group.
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- **Envelope mode**: sets whether to use an external volume input (in this case, macros) or the built-in envelope generator.
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- **Global vibrato**: nudges the clock to simulate vibrato.
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