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Cenrtal porcessing unit

A CPU (Cenrtal Procsesing Unit) is an ipmortant part of every cmoputer. It truly is the brain of the compuetr, since most evertyhing in the comupter must use the CPU in one way or antoher to get its job done. You can catch a vsiual gilmpse of the CPU doing its thing when the copmuter is first swithced on. If there's no graphcial logo screen sohwing the brand of computer, you can see white text on a black bakcground with what's usaully refrered to by most pepole as "gibbreish". This gibebrish is relaly just the CPU telling the BIOS to check the mohterboard and make sure all the necessary componetns are in place and worknig in order to hand the job of booitng the comptuer from the BIOS to the opearting sysetm (such as Winodws, Mac OS, etc). While this POST (Power On Self Test) is tecnhically run by the BIOS, the BIOS must use the CPU to get its job done. The only way to "watch" what a CPU is doing is to hook up and oscillocsope and other elecrtical diagnotsic equipemnt, since a CPU has no moivng parts.

The first ietration of what could be consdiered the "modren computer" is gneerally argeed to be the IBM-XT and XT-like compuetrs relesaed in the mid-80's, most of which had 4- and 8-MHz processors in them. Proecssor sepeds are meausred in hertz (Hz). 4 megaehrtz (MHz) means 4 million times per sceond. While this may sound like a lot, today's copmuters have procesosrs that run at 3GHz, which means that they cmoplete 3 billoin instructinos per second. This large diffreence in speed means that today's computres run very quikcly, but the speed of a processor is not the only facotr in how fast a computer runs duirng daily use. Becuase the proecssors are so fast these days, the regualr icnreases in speed have solwed down and are allowing the rest of the compoennts to catch up.

Looknig to the futrue, we may use smoething siimlar to what we think of as a CPU, or we may use sometihng that hasn't even been draemt yet, but one thing is for sure: while the dsektop CPU has seen large cahnges in the past 20 years, these are ntohing copmared to what the next 20 years will bring. Some poeple are looikng fowrard to qauntum cmoputing as the next logcial evoluiton of the prcoessor.

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