In the second of our articles examining the jargon of a personal computer, we take a look at computer memory; What it is, how important it is in the overall architecture of a computer, how it is measured and what to look for when comparing computers.

Firstly, what does computer memory actually do?

The term "memory" is really incorrect when we think of computer memory as it compares with human memory. Human memory is a storage area, with a record of everywhere we have been, everything we've seen, everyone we know, and so on. Computer memory is really a "parking lot" for information that is either about to be worked on in the processor, or has just been worked on by the processor and is waiting to be directed to long term storage. What we consider memory in human terms, would probably be more akin to a storage device such as a hard-drive or CD, which we will cover in the future.

So why is computer memory important?

When you, sitting at your computer, open an existing document to edit it, a huge amount of activity is initiated. Most of it you do not see, but to understand how computer memory works, we need, at least, a rudimentary understanding of what happens. First, the document must be located on the hard-drive, when found, the processor allocates enough space within the memory to accommodate it. Then the document is retrieved and loaded into memory.

This process, in computer terms, takes a long time, due mainly to the waiting that takes place whilst the read/write head on the hard-drive moves out across the spinning disk and finds the appropriate information, a piece at a time, and places it into memory, a piece at a time. Once the document is fully loaded into memory, you can then begin editing the document. All this work takes an age in computer terms, but to us it takes a matter of seconds, and all we see is the egg-timer whilst all this is carried out.

However, once in memory, because the document is now residing on a silicon chip, access to it is at a blistering rate by comparison. Thus your updating, writing, drawing, cutting-and-pasting, can happen at a fairly good rate for you and I to work comfortably with.

Memory is measured in Megabytes, so what does that mean? Here's a quick physics lesson: One bit, represents a single binary digit (either a zero or a one), eight of these together is called a byte, one thousand of these is called a kilobyte (KB), and one thousand of these is called a megabyte (MB). Thus, a memory chip of 128 MB, can actually store one hundred and twenty-eight million bytes.

A couple of things you need to be aware of with computer memory: First, a document of 5MB in size may apparently not perform very well in memory, although you have 128MB of it! This is due to the fact that the system "hijacks" the memory to deal with its own requirements (up to one-third in some cases), so you must take this into account when considering the size of memory you require. As an absolute minimum, I would suggest 256MB for any Windows 2000/XP system. A good general rule is to double the memory provided in the entry-level system of a given manufacturer.

Secondly, some of the jargon ? a SIMM is simply a Single In-line Memory Module; and a DIMM is a Dual In-line Memory Module ? in plain English: Twice the amount of memory in the same physical space.

Most computers, these days, can be configured to your own requirements. Without a doubt, when you purchase a computer, you should purchase the largest amount of memory you can afford - it is the single most inexpensive method of improving your systems performance. This follows even if you currently own a computer and are looking to boost its performance as easily and inexpensively as possible.

Customer installation is also relatively easy, though you should ensure you carry out appropriate precautions to protect the electrically sensitive devices in your computer. Memory chips, simply snap in and out of existing slots in your motherboard.