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What is Computer "Memory"? |
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Written by Michael Salsbury
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Wednesday, 13 July 2005 |
I've been working in the computer industry for almost 20 years now. During that time, I've heard a number of my less-technical friends and co-workers tell me that they're "running out of memory" on their computer. After I ask a few questions about what they mean, it's clear to me that they don't understand the difference between "memory" and "disk space". If they were to ask a salesperson at a computer store to sell them some "memory" for their computer, they might get some very expensive hardware that wouldn't solve the real problem. Just so that this doesn't happen to you, I thought I might give you a few different explanations of what "memory" and "disk space" really are, so that you know what to ask for and why.
An Analogy to Explain Memory and Hard Disk Space
Imagine that you work in an office, at a desk, and that your entire job revolves around doing things with pieces of paper. Imagine that you're not allowed to stack paper up on your desk in this theoretical job. That means you can only have a certain number of sheets of paper "active" at one time on your desk where you can work on them. Imagine that at quitting time, the cleaning people come through and clean up all the paper on your desk, throwing it into the trash.
In addition to the desk, let's also imagine that your office contains a filing cabinet. If you don't want the cleaning people to throw out something you have been working on, you need to lock it up in the filing cabinet before you go home for the night. Otherwise, it will be sitting on your desk and they'll assume it's trash.
In this analogy, the top of your desk (where all the "work" happens), is your computer's memory. Until you take something out of the filing cabinet and put it on the desk, it's empty. Similarly, until you create something new or load something you have previously saved, there is nothing of yours in the computer's memory. At quitting time (i.e., when you turn off the computer), everything in memory is deleted forever. If you haven't saved it to a hard disk drive for safekeeping (i.e., locked it up in the filing cabinet), you've lost it.
If you tell someone that you "need more memory", that is like asking your boss at work for a bigger desk. True, you might be able to get more done with a bigger desk. You might be able to get the same amount done more quickly if you had more room to work on. But if your filing cabinet is crammed full of paper, having a larger desk isn't going to prevent you from losing your hard work when the cleaning people arrive.
In computer terms, adding more RAM may make your computer faster (though that is not always true) or make it able to do more complex things, or both. But in the end, if there is no space in the filing cabinet (i.e., the hard drive), all that more complicated, faster work will be lost.
If you tell a computer technician that your "hard drive is full", you're telling them that you've run out of space to permanently store things on your computer. You're telling them that you either need help clearing off things you no longer need, or you're telling them you need to buy a new, perhaps larger, hard drive than you have.
That's why the difference is critical. If your problem is that your computer is giving you "out of memory" errors a lot, then you probably do need more "memory". But if you're not getting those errors, and the problem is instead that you can't save your work because the computer says it's "out of space" or "out of disk space", then adding all the memory in the world won't help you. What you need is a hard disk drive.
The Physical Difference Between Memory and Hard Disk Space
There are many kinds of computer memory out there. Most of it is provided in the form of a "chip" that looks more or less like the illustration below:
(Since there are literally dozens of kinds of memory and some look very different from the above, the memory in your computer may look radically different, or only slightly so.)
Doesn't look like much, does it? It's just a little circuit board with some integrated circuit chips attached to it. Because that's all it is, when your computer stores something in these chips, that "something" only lasts until the power goes out or the computer is "reset".
A hard disk drive, on the other hand, generally looks something like this:
As you might imagine with something this big, complicated-looking, and bulky, it has a lot more to it. It's all those extra components that allow the device to record information and store it for an extremely long period of time, even if the device isn't powered up. If you need more space to save, download, or store things on the computer, you probably need another (or a larger) one of these. It's essentially your computer's filing cabinet.
Now You Should Be In the Know
If you have followed the discussion above, you should now have a much clearer understanding of the difference between computer memory and disk storage space. This will help you the next time you need to deal with a computer technician at work or a salesperson at the local computer store. It should keep you from getting strange stares and help ensure that you take the right thing home with you when you go.
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Last Updated ( Wednesday, 13 July 2005 )
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