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All You Ever Wanted to Know About Computer Memory


The two main types of memory
One of the most confusing computer terms to non-techie types is "memory". Although the concept of computer memory can get quite complicated, at the surface level it's pretty easy. There are basically two types of memory in your computer -- random access memory (RAM) and disk "memory", which is more correctly referred to as "storage". The difference is that RAM memory is temporary storage that the computer uses while it's doing computations, displaying images, transferring data from the internet, etc. Nothing is ever saved in RAM -- it's continually be re-used for different things and when you shut down your computer everything that was stored there is gone.

Disk "memory", or more accurately disk "storage", is where the computer permanently stores data. For example when you retrieve your email the computer stores the various emails on your disk. And this data will stay there on your disk permanently, until you actually tell the computer to delete it. When you shut down your computer and then re-start it later, everything that is stored on disk will still be there.

All you need to know about disk storage
One of the more common mis-conceptions about disk storage is that how much you have of it and how much is unused will effect how fast your computer works or how fast it goes. For the most part that is totally untrue. A good analogy here is closet space. If you have a huge closet in your house for storage, and it's only a third full then there's really not much reason to go thru it and clean it out to make more room. You've already got plenty of space there to store more of your junk in, so whether it's a third full or even two-thirds full doesn't really effect anything. It's only when it gets to be 99% full and things are falling off the shelves that it becomes a "problem". And it's the same way with disk storage. As long as you have plenty of unused disk space, it really doesn't matter how much you have used and what it's used for. Your computer will function the same. It's only when you start running out that you need to worry about cleaning things up and deleting old files or perhaps uninstalling old programs.

How do you determine how much unused disk storage you have? Open up your "My Computer" icon by double-clicking on it, and then right-click on the entry there for your C drive and select "Properties" from the popup menu. You will then see summary statistics for your C drive that tell you how much is used and how much is free. A very rough rule of thumb here is that you should always have at least 250 megabytes (MB) free. If you have way more than that, you have nothing to worry about. But the closer the free space gets to 250MB, the more you need to think about doing some housecleaning.

All you need to know about RAM
As we noted, RAM is totally different than disk storage. Your computer is always using all the RAM it can get it's hands on, so there's no concept of "free" RAM versus "used" RAM. And because RAM is so critical to the performance of your computer, the more you have of it the better off you are. An analogy here is the size of your kitchen. If you live in a small apartment with a tiny kitchen, it's going to be rather difficult to prepare a gourmet 10-course meal. You can do it, but it's going to be clumsy and difficult. The bigger the kitchen, the easier it's going to be to work in. And that's the way it goes with RAM. You can get by with the bare minimum, but the more you have the faster your computer is going to work.

How do you determine how much RAM you have and how much you should have? Figuring out how much you have is easy -- right-click on the "My Computer" icon on your desktop and select "Properties". That will display a "System Properties" window, and towards the bottom of that display you will see your total RAM. If that number is expressed in KB (kilobytes), just lop off the last three digits to get your total in megabytes (MB). How much should you have? That's a hard question to answer -- as basically the more you have the better off you are. If you have anything less than 32MB you really ought to consider adding more if you can afford it. The "sweet spot" for most people is 64 to 128MB. And once you get to 256MB you are probably hitting the law of diminishing returns. And note that "your mileage may vary" here, depending on what version of Windows you have, as well as what application programs you typically use.