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by Duncan Kelly

FIRST THE SIMPLE EXPLANATION:

Random Access memory or RAM is small plug in cards that store all your computer's programs and data while the computer is running. As soon as you switch your computer off, this memory clears. So anything in RAM must be saved to the computer's hard drive if you want to keep it.

RAM is measured in Megabytes or Gigabytes. One byte is the amount of memory you need to store one character of text, like an "A" for example. So one megabyte can store about one million characters, which is roughly the amount in a best seller novel of 300 pages. Thus a gigabyte, which is 1,000 megabytes, will store around 1,000 of these books - a small library!

When you open a program on your computer, the requested program is copied from the hard drive and put into the RAM. If you open a second program, this too is loaded into the RAM. If your RAM gets full, then the computer starts a process called page swopping, where it frantically swops bits of data between the RAM and the hard drive to get the space in the RAM that it needs. This seriously slows down your computer, and so it is always best to have as much RAM as you can afford to prevent this happening.

Without RAM, your computer will not come on or display anything. Only the cooling fans will run. So it's a really important part of the computer.

NOW FOR THE TECH HEADS

RAM is a vast array of electronic switches, each one being either "on" or "off" which is equivalent to a logic 0 or a logic 1, and these switches are called bits. There are 8 bits in a byte. So one megabyte of RAM is 8,388,608 of these switches. (8 x 2 exp 20) Note that a megabyte is not a million bytes, but 2 to the power of 20, which is 1,048,576 bytes, as computers work on the binary system.

The plug in RAM cards consist of LSI ICs, that is: large scale integration Integrated circuits, this in order to squash many millions of circuits and components onto a single piece of silicone. The RAM available at the moment is normally DDR3 DRAM, which stands for Double Data Rate 3 - Dynamic Random Access memory. Quite a mouthful. Double Data Rate means that the RAM does 2 operations for every pulse of the memory bus, so it will operate twice as fast as standard RAM.

At the moment, computers need a minimum of about 512MB of RAM, and as computers advance, this figure will rise continuously.

Detailed information about RAM, the different types, how it works and what type of RAM your computer uses can be found here.

RAM is one of those things that works quietly in the background, and yet is an amazing technology and vitally important.

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