The SNES uses two master clock oscillators (21.477 MHz CPU/PPU, 24.576 MHz APU) that divide into 15 total clocks driving every chip in the console.
Key Takeaways
A 21.477 MHz ceramic oscillator plus a trimmer capacitor drives the Ricoh 5A22 CPU and PPU; the trimmer exists so technicians can compensate for oscillator drift over time.
The APU’s 24.576 MHz resonator divides down to SPC700 at 1.024 MHz, DSP sample rate at 32 kHz, and CIC clock at 3.072 MHz.
Official SNES developer documentation shows three oscillators; the “missing” third is the CIC copy-protection clock, actually derived from the APU resonator via division.
Enhancement chips like SuperFX (StarFox) tap SYS-CLK from the cartridge port; the CX4 (Megaman X2) bypasses this entirely with its own onboard 20 MHz oscillator.
Black-and-white video output on aging SNES units is often caused by a drifted oscillator; adjusting the trimmer capacitor or replacing the oscillator fixes it.
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