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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