Every computer has at least one heart which dictates the tempo to all the other chips. The CloCK output pin is connected to a copper line which spreads to most components, into their CLK input pin. Fabien Sanglard’s website looks at the clocks used on the Super Nintendo game console:

In the X2 slot, the blue thingy is a 24.576 MHz ceramic resonator. It is located on the side where the audio chips are so it sets the pace of the Audio Processing Unit.

In the X1 slot, the yellow one is labeled D21L3. It is a 21.300 MHz oscillator. It is located near (and sets the pace of) the CPU and the Picture Processing Unit.

The circuit diagram shows not two but three oscillators (there is one feeding the CIC chip, responsible for copy-protection).

There are only two “master” clocks in the console but none of the processors use them. What happens is that these masters go into dividers to create new clocks. The Ricoh 5A22 CPU for example, runs at 1/6 of the master clock, which results in 3.579545MHz. Luckily, the SNES community has documented all these dividers.

In total there are fifteen clocks in the Super Nintendo. Hopefully this solves the mystery of the “missing” oscillator from the documentation.

Read ll the details in the post here.