Note Frequencies

Equal-temperament pitches and the Commodore SID frequency-register values for each one. The SID columns show the 16-bit value and its hi/lo bytes; blank where the note runs past the chip's ceiling.

A4 reference

SID clock

Note	MIDI	Frequency	SID Fn	SID hex	hi	lo

SID output frequency is Fout = Fn × Fclk ÷ 16777216 (a 24-bit accumulator), so Fn = round(Fout × 16777216 ÷ Fclk) and the register takes hi = Fn >> 8, lo = Fn & 255. Fn is 16-bit, which caps the SID near 3.8 kHz (PAL); higher notes can't be played directly at this clock.