How a Computer CPU Works
History
A computer central processing unit (CPU) is a electronic board inside a computer that executes computer programs. In the early days of computers they were all different, making computers unique. As demand for personal computers grew CPUs are now mass produced in factories by specific manufacturers. This not only makes them more readily available but also cheaper to produce. Anything that runs a computer program, from certain cars to electronic toys for kids, has a computer CPU somewhere inside it.
Function
The function of a computer CPU is very simple. When activated, it executes a series of computer programs. These programs are the basic instructions for whatever electronic device it happens to be in. For example, in a computer the job of the CPU is to load and maintain the operating system. In a children's toy the function of a CPU might be to make something light up, or to trigger another electronic device that makes a noise.
The Four Steps
All computer CPUs generally execute the same four programs upon being powered on. The first step is called the "fetch" step, where the CPU actually retrieves the next part of the instructions from its memory. Next comes the step called "decode," where the instructions obtained in the first step are divided up among the other parts of the CPU. Then comes the "execute" step, where the directions are actually carried out. To go back to the example of a personal computer, this is the step during which the CPU actually loads the operating system of the computer. The final step is called "writeback," and is simply where the CPU makes a note of the results of the other three steps in its physical memory in case such a record should become necessary later on.