This is the first article in the Understanding Your Computer series from aworldofhelp.com. Our goal is to help people understand how their computer works, not simply tell them what they need to buy or use. When you know how your computer works, buying the right system or upgrade is easy. The series is designed to provide valuable information to users of all knowledge levels, so if part of it seems too complicated or too simple for you, I hope you read on and get all you can out of the articles. If you have questions or comments about this or any article, please ask in the forums!

RAM - What is it & why you need plenty

Many people picture a computer as consisting in part of a

Processor - CPU

Memory - RAM

Hard Drive

The way these three components interact is important to understanding how a computer works, and ultimately to understanding why you need enough RAM for your programs. Around the Internet and in Magazines you can find recommended RAM amounts for typical users. You also will find many places proclaiming RAM as the best performance for your dollar upgrade. I don't disagree at all, but I want you to understand what RAM actually does, and why it can be such a valuable upgrade.

I covered this subject briefly in the aworldofhelp Notebook Buyer's Guide on page 4. The information in that article is accurate, but I want to try to make things a little clearer here.

The article is divided into four sections, covering:

1. The functions of the three components we are discussing and their relative speeds

2. Why you need RAM and what takes up RAM

3. Multitasking and how RAM improves performance

4. How much RAM you need

CPU stands for Central Processing Unit. It is the brain of your computer. When you open a program, like Microsoft Word for example, the CPU reads through lines of computer code and follows the instructions so you can use your program. When you play an audio file like an MP3, the CPU has to do work to decompress it while it plays. When you edit a picture the CPU has to perform many calculations to make even the smallest changes.

One thing to note is that the CPU actually does have a very small amount of memory in it. This is the fastest memory in a computer system, but it is so small it doesn't really affect this article. Generally speaking, the CPU doesn't store the information that makes up the program, MP3, or picture, it only processes it. The data has to be located somewhere in your computer, and the CPU has to find it and then retrieve it.

That action, the problem of locating the data and how it affects your overall system performance is what this article is about.

RAM

RAM stands for Random Access Memory. This memory is very fast, and you will see it in sizes like 256 MB, 512 MB, or 1024 MB. When you turn off your computer, the contents are erased, so it is only temporary memory. This is where the CPU looks first to get data to process. So if you are editing a picture, and its data is in this RAM, because RAM is fast memory, editing the picture will happen relatively quickly.

Hard Drive

Your Hard Drive is where you store all of your programs, music, video, and everything you keep on your computer. This is the memory where you store your files that remain even after you turn your system off. You will see them in all sizes, now typically ranging from 30 GB, to hundreds of GB. Hard drives are very slow compared to your CPU and RAM because they are mechanical. Inside the disk there are actually small readers that physically move around to locate and read data.

If you are editing a picture, the CPU will first look in RAM memory to see if it is there, because RAM is fast. If it isn't, the CPU will go to the hard drive and edit the picture there. Because your hard drive is so slow, this takes a much longer time than if the picture had been in RAM.

Again, the CPU only stores a tiny bit of data, so it has to get it from somewhere to operate on. If the CPU has data to process, it will do so as fast as it can, but if it doesn't, the brain of your computer simply sits and waits doing nothing. Only after it finds and retrieves the data it needs can it process it.

So ideally, you want your CPU to find data in the fastest place possible. As you can see, if the data is in RAM you are far better off than if it is in your hard disk because RAM is so much faster. Just take a look at the graph below. It shows the time it takes to access each memory type in nanoseconds.

Clearly, your hard drive is slow, but when you look at the above graph, and you see the numbers it is based on below, you realize just how slow it is. Each is an approximate access time in nanoseconds:

CPU 1 ns
RAM 60 ns
Hard Drive 10,000,000 ns

It should be clear why the bars for your CPU and RAM do not even show up on this graph, your hard drive is simply extremely slow.

So why bother with a hard disk?

Seeing that, you might think that it would be great if you could just use huge amounts of RAM instead of a hard disk. You are right, this would be a great situation, but as you might imagine, the faster the memory in your computer, the more expensive it is. RAM prices have come down significantly in recent years, but it will still cost you much more compared to Hard Drive space.

Computers work within this constraint - that faster memory is more expensive - by looking in the fastest place for information first, then moving to slower locations only when they need to. So if you hear your hard drive making noise or you see a light telling you it is being accessed, you know the data could not be found in RAM.

Now you know that the hard drive access that's going on is very slow, and that is the reason your CPU, and in turn you, have to wait.

So now you know that you want lots of RAM, at least enough for all your programs, so you don't have to access your slow hard drive too often. But what actually uses your RAM, and how can you see whether your system has enough?

Windows itself takes up a lot of RAM. Microsoft says Windows XP will run on a machine with 64 MB of RAM, though they recommend 128 MB or 256 MB. If you have even more RAM than that, and I recommend you do, Windows will use some of it as well.

Everything that loads when you boot up your computer also uses RAM. What these programs are actually doing is putting themselves in to RAM, if enough is available, so that they can be used very quickly. The problem is when there isn't enough memory for all these programs, and your computer runs very slowly.

On my machine these programs load when I turn on my computer:

AVG Antivirus Scanner Software Digital Camera Software Gmail Notifier AOL Instant Messenger And some server software for testing

Then, everything I run after the boot up uses more RAM. Whatever Internet Browser I use, for example, takes up RAM. Microsoft Word does too, as well as all my programs. To see how much RAM you have and how much free RAM you have, you can open up Task Manager by right clicking on the start menu and selecting it, it looks like this.

On the right, in the Physical Memory section my RAM is listed. My total and available memory is listed, and as you can see, just booting my computer into Windows XP and loading all the things I do, I have less than half of my RAM available for other programs.

Your system will probably have less total RAM, but you'll be able to see how much and how much you have free. You can easily find out how much ram you have by right clicking on "My Computer" and going to properties, but it's useful to see it here so you understand what the Task Manager is showing. You can use this tool to convert the number shown in "K" to a number that you may be more comfortable with, in "MB".

K MB

On my computer, 1048040 K converts to 1023.4 MB, which is 1024 MB.

Your own system may give you a number a few megabytes lower than the actual. For example, 252 instead of 256. That is normal, and is a result of something else, like a video chip, using a portion of the RAM. The actual RAM your programs has to work with is the number listed in the Task Manager.

In my example, I have a hundreds of Megabytes of free RAM. I sometimes fill the RAM if I am video editing or photo editing, but beyond that, it is rare. This is a good thing though, remember the chart. If your RAM is full, your Hard Drive will be used more, and since it is so slow, your system will grind to near a halt.

By looking at the Task Manager, you can get a good idea of how your system is running. If you have lots of available RAM, you are in good shape. But many systems I see actually have almost no free RAM, and this is what causes the system to use the hard disk instead and run slower. Note that the available RAM will generally never hit zero, but will fluctuate around very low numbers if your system is out of memory.

Our example so far has been simplified to show how doing one thing on your computer needs memory. But a real benefit of having adequate memory is multitasking. Basically, if you are doing more than one thing at a time, you are multitasking. If you are reading this article and editing a picture at the same time, you are multitasking.

Generally, if you can switch between two open programs on your machine very quickly, they both are loaded into RAM. In this case, you can likely see plenty of available memory in Task Manager. On my machine, since I have plenty of RAM, I switch between two or three Internet browsers, Excel, PowerPoint, Instant Messenger, my audio player, and more very quickly.

On the other hand if you don't have enough RAM, even with just two programs open, when you switch between them your computer may slow down considerably. The program you are switching to is not in RAM, and the CPU is forced to get information from the hard disk. As you open more programs, the situation only gets worse. A check on task manager in this case will likely show very little free RAM, too little in fact to fit all your programs.

How Much RAM do you need?

The best answer is that you need enough RAM to run all your programs and multitask between them quickly. If your system is running well and you check Task Manager and have lots of available RAM, you are probably in good shape. If your system is slow switching between more than one program, look at the task manager and see if your available RAM is low. If it is, adding more will likely make your entire system run faster, just by fitting more programs into RAM.

You'll be amazed how fixing this problem will improve you computing experience overall. That is the reason so many people talk about RAM as being the best upgrade for older systems.

If you are buying a new computer 512 MB is a good amount of RAM for most users. If you edit a lot of pictures or video, or if you can just afford the upgrade, moving up to 1024 MB (1 GB) is not a bad idea. Memory prices are much lower than they used to be, and you'll have extra memory for more programs now. For most users, the biggest advantage to getting more RAM is that if you keep your computer for a long time, the extra RAM could save you an upgrade down the road.

But how much RAM is too much? Well you won't really slow down your system by adding RAM. Typical systems currently can accommodate up to anywhere from 512 MB - 2 GB of RAM. The problem is, after you have enough RAM, adding more really doesn't get you much, if any performance gain.

With that in mind, check back soon for an article comparing performance of common applications, including multitasking, with different amounts of RAM. We'll test from 256 MB to 1024MB, and you'll be able to see how all we've covered here has a real affect on the speed of your computer.

Steve Perlow is the founder of aworldofhelp.com, where you can find the aworldofhelp Top Picks in desktop and notebook systems.

Visit aworldofhelp.com to get answers from real people to your questions about technology, travel and more.