In a computer, clock speed refers to the number of pulses generated by an oscillator that sets the tempo for the processor. The faster the processor can access data, the faster the computer can perform its functions, given that other parts of the system are sufficiently tuned to support the particular clock speed. Clock speed is determined by a quartz-crystal circuit, similar to that used in radio communication equipment, and is measured in megahertz (MHz)or even gigahertz (GHz.)