Computers: Power and Memory

This article was first written for It’s one that covers a nugget of information that I’ve had to explain to non-technical people regularly.


Do you understand your computer? Many don’t. Often when a computer slows down somebody will suggest that you get more memory. Will that help? Read on to find out.

There are two parts of a computer that can correctly be referred to as “memory”. The first is the RAM and the second is the hard drive. You may hear people refer a number of “gig” or “meg” regarding each of these.

Imagine for a while that you are your computer.

– The closest analogue to the RAM memory is how much that person can remember.
– The most similar thing to the hard drive is a person’s pockets.

A hard drive is used for holding information, it’s a form of storage. The information that goes there is semi-permanent. It will sit around until it is deliberately destroyed. When you put information on your computer it’s like putting a book full of notes into one of your pockets. If you have huge pockets you can store more information and when you run out there’s not much that can be done short of getting clothes with more pockets (which is what you do when you upgrade your hard drive).

RAM is short for “random access memory” and that is how much your computer can remember at once. It’s a more short term type of memory, it’s not really meant for holding things forever. It’s like a you trying to remember a sequence of numbers, or someone’s address or even what six items you need to collect from the kitchen. You may only need this information for a brief time and may not even realise that you are holding the information – it just goes in and out of your head as and when needed.

There is a third kind of memory. This is called “virtual memory” and that is when your computer writes temporary information to the hard drive. This breaks the pattern described above to some extent but the analogy holds true. Suppose you were in a bar and buying drinks for all your friends. You might be able to remember the order but there is a chance that you won’t because there is so much you have to keep in your head at once. If you find yourself in this situation you might scribble down the order and stuff the note into your pocket. Your computer does the exact same thing – it doesn’t want to keep the information forever, but if there’s simply too much to keep in the RAM it will make use of the hard drive.

Sometimes people think that because their computer is running slowly, they need to delete files. This may work if you are very short of space as it will free up extra space for the computer to put its temporary information. The truth is, though, only a small portion of your hard drive is reserved for this kind of use and if you are impinging on that space then the chances are you actually need to upgrade to a bigger hard drive where you can store more permanent information.

If you want to improve the speed of your machine buying extra RAM is often the best way to do it as it lets the computer make more calculations at the same time. Imagine if you could improve your memory so that you needed to write down only a fraction of what you might need to now. Most of what the computer holds in its memory is complicated calculations and the more it can hold at once the more work it can do. Buying RAM can be a tricky business, though, so make sure you know what kind your computer needs. It is an expensive component and if you put in the wrong type it will probably melt!

The final way of upgrading your computer and having it work faster is to purchase a new CPU. The CPU is the computer’s processing unit – that is, its entire brain, rather than just the memory section. It is the bit that takes the information from the memory and performs the calculations and throws the right bits of information back into the memory, performing commands if necessary, such as triggering other hardware or sending information to the graphics card so it can be written to the screen. While you can upgrade this component, it is probably the most expensive part of a machine and it is tricky to replace – adding memory or hard drives just involves swapping or adding parts into slots designed to hold extra bits, but removing the CPU is more like dismantling your machine. If you are finding your CPU isn’t up to the jobs you want it to do it might well be worth investing in a whole new machine instead of upgrading what you have.

A powerful machine will run a combination of a high power CPU with lots of memory. Your hard drive doesn’t directly contribute to how fast and powerful your machine is, although the bigger it is the more you can hold so a good machine will have a large drive, or perhaps more than one.

If you bear this in mind when looking for a new machine or components for your current one then you ought not to go too far wrong.