57 lines
1.7 KiB
Markdown
57 lines
1.7 KiB
Markdown
# tildearrow Sound Unit
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a fantasy sound chip, used in the specs2 fantasy computer designed by tildearrow.
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it has the following capabilities:
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- 8 channels of either waveform or sample
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- stereo sound
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- 8 waveforms (pulse, saw, sine, triangle, noise, periodic noise, XOR sine and XOR triangle)
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- 128 widths for the pulse wave
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- per-channel resonant filter
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- ring modulation
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- volume, frequency and cutoff sweep units (per-channel)
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- phase reset timer (per-channel)
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# effects
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- **`10xx`**: set waveform
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- 0: pulse wave
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- 1: sawtooth
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- 2: sine wave
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- 3: triangle wave
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- 4: noise
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- 5: periodic noise
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- 6: XOR sine
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- 7: XOR triangle
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- **`12xx`**: set pulse width (0 to 7F)
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- **`13xx`**: set resonance of filter (0 to FF)
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- despite what the internal effects list says (0 to F), you can use a resonance value from 0 to FF (255)
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- **`14xx`**: set filter mode and ringmod
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- bit 0: ring mod
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- bit 1: low pass
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- bit 2: high pass
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- bit 3: band pass
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- **`15xx`**: set frequency sweep period low byte
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- **`16xx`**: set frequency sweep period high byte
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- **`17xx`**: set volume sweep period low byte
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- **`18xx`**: set volume sweep period high byte
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- **`19xx`**: set cutoff sweep period low byte
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- **`1Axx`**: set cutoff sweep period high byte
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- **`1Bxx`**: set frequency sweep boundary
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- **`1Cxx`**: set volume sweep boundary
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- **`1Dxx`**: set cutoff sweep boundary
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- **`1Exx`**: set phase reset period low byte
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- **`1Fxx`**: set phase reset period high byte
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- **`20xx`**: toggle frequency sweep
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- bit 0-6: speed
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- bit 7: up direction
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- **`21xx`**: toggle volume sweep
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- bit 0-4: speed
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- bit 5: up direction
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- bit 6: loop
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- bit 7: alternate
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- **`22xx`**: toggle cutoff sweep
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- bit 0-6: speed
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- bit 7: up direction
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- **`4xxx`**: set cutoff (0 to FFF)
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