Memory 

Memory –  Everyone benefits from having a good memory. Right? You study for a maths exam and you remember facts and figures and you’re all ready for the big day. You remember what time you should be there. You even remember to take a pen. You remember all those facts and figures and you write a dazzling paper, the examiners are stunned by your dazzling maths skills and give you an A++ with distinction.

What about the kinds of memory you get in a computer system? How do they work and how do they store data?

Firstly, let’s talk about volatile memory and non-volatile memory.

Volatile memory relies on a power source to store information, rather like you needing to concentrate so that facts sink in. If you don’t pay attention in class, or you have a really bad memory, facts will go in one ear and out the other and you won’t remember a thing. It’s the same with volatile memory. As soon as you switch off, all that information is lost.

Non-volatile memory remains in place even when the power is switched off. So for instance, you could be concentrating in class and you take everything in and you remember it. When you get home you re-read what you learned in class which reinforces the knowledge you stuffed inside your head, so that even if you go to sleep or you switch off and do something else like go dancing or play football, the memory of those facts is still there and you can retrieve it.

The third type of memory is called virtual memory. A computer system might be using a set allocation of random access memory (RAM) but you need to run another programme and there isn’t enough RAM for you to do that. The computer grinds to a halt and tells you that you don’t have enough space to run that extra programme and would you kindly shut down one of the other programmes if you want to continue.

That’s a problem if you need all those programmes running. So what the system does is access extra space in another part of the computer system and copies it into the hard drive. What a concept, transferring space! But that’s what it does, and that’s what gives you the virtual memory to run that extra programme.