A picture plays left to right over TIME; each row from the bottom is one harmonic (1 to 256), and the brighter the pixel, the louder. A sound is analysed into the harmonics of its pitch and plays back at any note. AMOUNT mixes it with the timbre.
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Flip the power switch, then play with Z–M (lower octave) and Q–P (upper octave), sharps on the row above each, or click the keys. Hold Space as a sustain pedal. A MIDI keyboard (notes, pedal, pitch wheel) works too in Chrome and Edge once the power is on. Every sound is a sum of up to 256 sine-wave harmonics: the screen shows them, and the filter curve shaping them.