What is the CPU?

Posted By BrokenClaw on September 12, 2007

The central processing unit, almost always abbreviated and pronounced CPU, is the brains of the computer. It is a small chip, about the size of a matchbook, black in color, attached flat on the motherboard. It does all of the mind-numbing computations, and it controls the other components. It is the CPU that distinguishes the power of one computer from another.

CPU with heat sink and fanHistorically, computing power has been measured by the speed, often called clock speed, at which the CPU does computations, described in cycles per second, or Hertz (Hz). CPUs have advanced in the last 30 years from running at 4 megaHz (million cycles per second) to nearly 4 gigaHz (billion cycles per second). In other words, CPUs today are a thousand times faster than they were in the first home computers.

In years past, computers in the IBM-Intel-Microsoft line were often differentiated in terms of the CPU. The first modern CPU was the Intel 80286, which became known by the shortened name, 286. That generic nomenclature was followed by the 386 and then the 486 by Intel and its competitor, AMD. The Intel 486 line was succeeded by the PentiumĀ®.

Today’s processors have differentiated themselves in a more complicated manner, so it’s difficult to lump them into generic classes. Modern CPUs consist of more than one computing core. In other words, they use technology which allows them to behave like more than one CPU operating simultaneously. The terms dual-core or multi-core are used to describe this configuration. As a result, the clock speed of the processor is no longer the primary point of comparison between one CPU and another. However, only very high-intensive computational applications, such as video manipulation and video gaming, are currently programmed to take full advantage of the multi-core processors.

Performance of a CPU can be measured by the speed at which it does complicated mathematical computations, known as floating point operations. The unit of measure is called flops (floating point operations per second). The singular form, flop, is also used as a number, along with the usual prefixes: megaflop, gigaflop, teraflop, etc.

As an electronic device, a computer produces a tremendous amount of heat, requiring a full-time fan to keep it from overheating. In desktop computers, the CPU is always attached to an aluminum heat sink (see photo) with its own fan in order to dissipate the heat. The combination of heat sink and fan makes the CPU easily identified on the motherboard. With laptop computers, since there is virtually no open space inside the case, the heat is not so easily dissipated. That’s why having a laptop actually on your lap can become quite uncomfortable from the heat.

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