What is a CPU?

by techtiptom

Originally posted to wibc.com on 02/21/2011

If you’re in the market for a new computer, it’s necessary to understand the function of a CPU. Also known as the Central Processing Unit or processor, the CPU is essentially the “brains” of your computer. Without the CPU, you wouldn’t be able to play games, type research papers, or surf the Internet. Your computer would basically be a very expensive paperweight.

Sometimes people mistakenly believe the case or chassis of a computer is the CPU. However, a CPU is an internal component of the computer. You can’t see it from the outside of the system; you’d have to peek inside and remove both the CPU heat sink and fan to get a good look.

The first CPUs were used in the early 1960s. They were custom designed as part of a larger computer, making them prohibitively expensive. Once engineers figured out how to mass produce the CPU, personal computers became more affordable for the average American. With the introduction of the integrated circuit in the late 1970s, it became possible for smaller CPUs to be manufactured as well. This helped transform computers from large, bulky devices that took up entire rooms to more manageable desktop and laptop models.

Today, Intel is the best-known manufacturer of computer CPUs. No matter what type of computer you have, however, your CPU works by executing a series of stored instructions known as a program. Most CPUs conform to the von Neumann architecture, which says that the CPU must fetch, decode, execute, and write back the data in a fairly rapid succession.

CPUs are sometimes called microprocessors, although these two terms are not quite interchangeable. The microprocessor, first introduced in the 1970s, reduces the word size of a CPU from 32 bits to 4 bits in an attempt to allow the transistors of the logic circuits to fit on a single part. Often, it takes more than one microprocessor to perform all of the functions of a CPU. Microprocessors are also commonly used in cell phones, automobiles, and children’s electronic toys.

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