The clock signal in a microprocessor allows synchronization of several components of the microprocessor. The correctness of the computation of the microprocessor depends upon efficient and balanced distribution of the clock signal. The clock generator generates the clock signal.

Those type of clock have a small antenna built into their circuitry. This picks up a constant radio signal transmitted from an atomic clock (an extremely accurate device). The signal is constantly broadcast - meaning the clock can pick up the signal at any time of day or night. The clock's circuitry simply changes the display to match the incoming signal.

It is the ratio of the on and off time or the clock signal, which is generated by the clock generator...

clock signal divider

The control signal is generated by the systems clock. The systems clock is called a crystal and runs at a constant speed. Typically measured in Mhz