What is a CPU?

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  • Written By: Dana Hinders
  • Edited By: O. Wallace
  • Last Modified Date: 04 October 2019
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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 heatsink 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 writeback the data in a fairly rapid succession.

Since the CPU is one of the most important parts of a computer, it should come as no surprise that it is also the most expensive. In fact, if your computer is more than three years old and your CPU has been damaged by static electricity or some other factor, you may want to consider upgrading to an entirely new computer. A newer, faster CPU will often provide enough additional computing power to make the purchase a wise investment.

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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Post 15

Microsoft does not make intel cpus, Intel corporation does. Intel also makes celerons, as celeron is an Intel product.

Post 12

As computer words get larger and larger, there is a law of diminishing returns; the speed execution of application programs does not increase. In fact, it decreases. Why is that?

Post 11

How can I tell if the CPU is bad on a dead PC?

Is that replaceable on its own or must the motherboard be replaced?

Is a shop diagnostic test enough to determine a bad motherboard?

Post 8

thanks. the information is very helpful.

Post 7

@katin – Yes, the CPU is evolving at an incredible pace. In recent times, CPU manufacturers have realized there are practical limits to how fast internal clock speeds can be driven.

When the practice of manufacturing processors with faster and faster clock speeds began to show diminishing returns, companies like AMD and Intel thought of a simple and elegant solution to dramatically increase performance: just add more processors!

As time goes on, you should expect to see the number cores in a CPU multiply. In fact, AMD just released a consumer six-core processor!

Post 3

CPUs have evolved quite a bit since first introduced. Microsoft provides intel and celeron chips, while AMD offers Athlon and Duron or Sempron. You've probably heard of intel core, core 2 Duo, core 2 quad, Athlong 64, but what does all this mean? Simply put, a single core CPU functions solo, like a human brain. The core 2 Duo is a dual processor, and no, there is only one CPU on the computer not two; but, so it will function like it had two brains, it has separate L1 cache for each core, and shares the L2 cache between the cores and therefore, no need to duplicate data. The core 2 quad, you guest it, has 4 cores on a single CPU. Each core has a L1 cache, and the L2 cache is shared by cores 3 and 4.

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