furnace/papers/doc/7-systems/soundunit.md

TildeArrow Sound Unit

This is a fantasy sound chip, used in the specs2 fantasy console designed by tildearrow. It includes native support for sample playback, but with only 20K of sample data. Since 0.6pre1, this sound chip is no longer hidden by default and can be accessed through the module creation screen and can be added or removed.

Effects

10xx: set waveform

• 0: pulse wave
• 1: sawtooth
• 2: sine wave
• 3: triangle wave
• 4: noise
• 5: periodic noise
• 6: TODO find name for waves 6, 7
• 7: TODO find name for waves 6, 7 12xx: set waveform (0 to 7F) 13xx: set resonance of filter (0 to FF)
• despite what the internal effects list says (0 to F), you can use a resonance value from 0 to FF (255) 14xx: set filter mode and ringmod
• bit 0: ring mod
• bit 1: low pass
• bit 2: high pass
• bit 3: band pass 15xx: set frequency sweep period low byte 16xx: set frequency sweep period high byte 17xx: set volume sweep period low byte 18xx: set volume sweep period high byte 19xx: set cutoff sweep period low byte 1Axx: set cutoff sweep period low byte 1Bxx: set frequency sweep boundary 1Cxx: set volume sweep boundary 1Dxx: set cutoff sweep boundary 1Exx: set phase reset period low byte 1Fxx: set phase reset period high byte 20xx: toggle frequency sweep
• bit 0-6: speed
• bit 7: up direction 21xx: toggle volume sweep
• bit 0-4: speed
• bit 5: up direction
• bit 6: loop
• bit 7: alternate 22xx: toggle cutoff sweep
• bit 0-6: speed
• bit 7: up direction 4xxx: set cutoff (0 to FFF)