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63 lines
2.1 KiB
Markdown
63 lines
2.1 KiB
Markdown
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# 5E01
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a fantasy sound chip created by Euly, based on the Ricoh 2A03, with some improvements:
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- a 37.5% duty cycle,
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- 32 noise pitches instead of 16, and
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- triangle channel becomes a wave channel, with four available waveforms: triangle, saw, sine and square.
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## effects
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- `11xx`: **write to delta modulation counter.** range is `00` to `7F`.
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- this may be used to attenuate the triangle and noise channels; at `7F`, they will be at about 57% volume.
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- will not work if a sample is playing.
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- `12xx`: **set duty cycle/noise mode/waveform of channel.**
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- may be `0` to `3` for the pulse channels:
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- `0`: 12.5%
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- `1`: 25%
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- `2`: 37.5%
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- `3`: 50%
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- may be `0` or `1` for the noise channel:
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- `0`: long (15-bit LFSR, 32767-step)
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- `1`: short (9-bit LFSR, 93-step)
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- may be `0` to `3` for the wave channel:
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- `0`: triangle
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- `1`: saw
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- `2`: square
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- `3`: sine
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- `13xy`: **setup sweep up.**
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- `x` is the time.
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- `y` is the shift.
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- set to `0` to disable it.
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- `14xy`: **setup sweep down.**
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- `x` is the time.
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- `y` is the shift.
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- set to `0` to disable it.
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- `15xx`: **set envelope mode.**
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- `0`: envelope + length counter. volume represents envelope duration.
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- `1`: length counter. volume represents output volume.
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- `2`: looping envelope. volume represents envelope duration.
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- `3`: constant volume. default value. volume represents output volume.
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- pulse and noise channels only.
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- you may need to apply a phase reset (using the macro) to make the envelope effective.
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- `16xx`: **set length counter.**
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- see [NES](nes.md) for more information.
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- this will trigger phase reset.
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- `17xx`: **set frame counter mode.**
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- `0`: 4-step.
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- `1`: 5-step.
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- `18xx`: **set PCM channel mode.**
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- `00`: PCM (software).
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- `01`: DPCM (hardware).
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- when in DPCM mode, samples will sound muffled (due to its nature), availables pitches are limited, and loop point is ignored.
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- `19xx`: **set triangle linear counter.**
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- `00` to `7F` set the counter.
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- `80` and higher halt it.
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- `20xx`: **set DPCM frequency.**
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- only works in DPCM mode.
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## info
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this chip uses the [NES](../4-instrument/nes.md) instrument editor.
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