The Brains of the Computer
The main "box" of a computer - the tower or systems unit is like your head. It holds your brain, but it has other things as well. The thinking part is the CPU (central processing unit.) This part is also called a processor. Unlike our brains, however, it's just a little computer chip, which is usually smaller than a credit card. Like your brain, it does the processing for the computer, but on its own it's worthless.

Processors (A kind of computer chip)

How can you tell when one CPU is better than another CPU? If you go to a computer store or web site, the computer listings have all kinds of numbers that may not mean anything to you. A few years ago, when you bought a computer, it only had one processor, but now it's more common to find computers with several processors that work together. It's like an organization that can get more done if they divide up the work load between several employees, instead of one person doing it all.

The number of processors and the speed of the processors is constantly changing (or they couldn't get you to buy a new computer!) The main number you need here is something like 2.4 GHz (giga hertz). Although that number is from April 2004 and subject to change in a week, that's about 3,400,000,000 processes per seconds! Of course, a lot of those processes are just the computer keeping itself going.

A little translation:
    giga - about a billion
    mega - about a million
    kilo - about a thousand
    byte - the amount of space it takes to store one letter
    hertz - cycles per second (processes in computers)
All this stuff is measured in binary (remember base 2 from school). Most of us would rather not think in binary, so the numbers above are approximately the "normal" number equivalent.

Motherboard

There are many other things in the tower besides the CPU. The CPU needs to be connected to the other parts of the computer. These connections come through the motherboard.

A motherboard looks kind of like the green, flat Lego boards kids (young and old) can build towns on. Every device in the computer has to be linked to the processor through the little wire roads on the motherboard.

Thanks to atmarkit.co.jp for the pictures.

Memory (RAM)

Although most of the information in your computer is stored in the hard drive, your computer can't directly use the information on the hard drive. It has to put the information into Memory. Then the CPU can get the pieces of information as it needs them.

Real life example: Think about your address book as the hard drive. You can't possibly remember all the addresses you need; so, you write them in your address book. But, a address can't jump from your address book onto an envelope. So, you read the address and then your hand can write it on the envelope. The computer works the same way. The information is on the hard drive. The needed information is copied into memory. Then the CPU
can use the information to do work.

Thanks to tigerdirect.com for the RAM graphic.

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