CompTIA A+ Certification All-in-One Exam Guide

wire (most diagrams label the clock wire CLK). A charge on the CLK wire
tells the CPU that another piece of information is waiting to be processed (see
Figure 3-9).
Figure 3-9 The CPU does nothing until activated by the clock.
For the CPU to process a command placed on the EDB, a certain
minimum voltage must be applied to the CLK wire. A single charge to the
CLK wire is called a clock cycle. Actually, the CPU requires at least two
clock cycles to act on a command, and usually more. In fact, a CPU may
require hundreds of clock cycles to process some commands (see Figure 3-
10).