Many of you will already understand the concepts in this article, but I thought it worth touching on this month. As usual, the technophiles among you can offer more in depth information, but our target audience here is the average computer user who simply wants to make their computer run better without wading through a lot of geeky details. I am going to explain what computer memory is and why you need as much as you can get.

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There are basically two types of memory: RAM (random access memory) and a Hard Disk (or Hard Drive). However, when one refers simply to computer “memory”, one always refers to RAM. Hard disk memory is called "Disk Space." This article concerns RAM memory, but first, I will explain the difference between the two by way of analogy...

Think of hard disk memory as a library of books in a large room with hard to reach shelves. Now imagine RAM as a table in that library where you are doing research. If you have an open book on your table, it doesn’t take long to access the information in that book. However, if you need information from another book not on your table, you must get up from your table, go over to the card catalog file, find out where the book is on the shelves, go over to the shelf, climb up a ladder and nab the book (that is assuming you understand the dewy decimal system and no one has robbed the book). Obviously, information can be accessed much quicker from an open book on your desk (RAM) than it can from a book on some remote shelf (hard drive).

Now, if you’re at a very large table, you can have more open books on it, but if you’re at a small table, you can have a limited number of books on it, which would necessitate many long trips to the card catalog and book shelves. And you can’t keep your books on the floor or on the table next to you because the librarian is an officious little prick. So the larger your table (RAM) the more information you have at your fingertips. RAM is hundreds of times faster than a hard drive.

This is exactly how your computer works. When you open a file or application, your computer tries to load the data into available RAM. If you do not have available RAM, then your computer must reference the data from your hard drive which takes a lot more time. Therefore, more RAM = more speed.

How Much Memory Do You Need?

With today's operating systems (Windows XP, Vista and Mac OS X), you need a MINIMUM of 1 GB (gigabyte) to work efficiently, but 2 GB is HIGHLY recommended. More than this and your computer will work even faster and more stably, especially with high-end applications such as video and audio production, CAD, graphics, etc; these types of applications usually need a minimum of 4 GB of RAM. Also, the more applications you keep open at the same time, the more RAM you need. Remember, the less a computer has to access the hard drive, the better.

Every computer has limitations on how much RAM can be added. Modern low-end consumer models can often only accept 2 GB. Windows XP can only access 4 GB of total RAM, and Vista 16 GB. The Mac OS itself does not have these limitations, but individual Macs have their own limits (2 GB is minimum and high-end Macs can access up to 32 GB).

How to Find Out How Much Memory You Have

Mac Users:

1. From the "Apple" menu at the top-left corner of your screen, go to "About this Mac."
   
          

PC Users:

1. From the "Start" menu at the bottom-left corner of your screen, go to "My Computer", then right-click, then go down to "Properties." (Vista Users: "My Computer" is simply "Computer")
   
   
   

How to Buy More Memory

The cheapest place to buy memory is on the web. To find memory for your particular computer, simply do a Google search for "My computer model" +RAM. e.g: "MacBook" +RAM, or "Dell Inspiron 15" +RAM. 99% of the time, this is all you need to do to find the RAM you need.

And now, the geeky caveats... Occasionally, your particular model name may include several versions which require different types of RAM. Older MacBook Pros, for example, use 'PC2-5300' whereas the newer models which are still called 'MacBook Pro' require 'PC3-8500'. If you want to be sure of memory for your Mac, download the free 'MacTracker' which is the best Mac reference since Steve Jobs was in his nappies. PC users can use the Kingston Memory Finder or the Crucial Memory page.

The best way to determine exactly what type of memory you need and where to get the cheapest price is to determine the 'Module Name'. In modern memory chips, this designation always starts with 'PC'. e.g.: PC-3200, PC2-5300, PC3-8500. This number tends to gets larger for newer computers. If you can determine the module name you need, you can do much more comparative shopping. NOTE: Macs and PCs today use the exact same memory. If your computer requires PC-3200, you can get it anywhere, as long as you get PC-3200. Also, you also need to indicate if you have a desktop or laptop. The difference will be in the number of 'pins' (connectors). For example, PC2-5300 has 2 types: 240 pin = desktop memory, and 200 pin = laptop memory. Other module types have different pin configurations.

I have found that in general, all memory brands a more or less the same, Kingston and Newer Technology are popular and tend to be good, but the companies simply buy their stock from generic Chinese manufacturers and put their name on it.

Nice Wikipedia Article on memory (geek alert!).

How to Install Memory

Installing RAM is always easy on all modern computers, and is almost always considered a 'User installable part' by computer manufacturers (i.e.: it won't void your warranty if you do it yourself). Mac users should start with the Mac Repair guides on iFixit's web site. PC users should start with the Kingston 'Ultimate Memory Guide'. If none of these resources are helpful, google "how to install RAM" + "YOUR COMPUTER MODEL". And if all else fails, take it to your friendly local computer repair person. Never pay more than $20 to have anyone install RAM for you.

Further Reading on Types of Memory (geek alert!)

This section will explore and expound upon this fundamental concept in computers: memory. Because memory is a generic term for “storage device”, we should underscore that – in terms of modern computers – there are two main different types of memory: RAM (random access memory) and Hard Disk.

Temporary memory: RAM

When a technogeek uses the term “memory”, this is generally referring to the temporary storage space known as RAM. When a program is launched, the contents of that program must be placed into a temporary memory so the processor can interact with it. RAM is known as volatile memory: it must be continuously powered to retain information. Additionally, it is essential to the operation of a computer. The idea of RAM as an all-encompassing word for fast temporary memory is a misnomer, but nonetheless, is common vernacular.

Random-Access Memory

Semi-permanent memory

The other major type of memory is hard disk drive (HDD). More recently, a technology known as solid-state disk (SSD) is beginning to replace HDDs, however, they effectively serve the same purpose. Unlike RAM, this semi-permanent storage need not be supplied with continuous power to retain its contents. Therefore, it is known as non-volatile memory. Although included in modern computers, a hard drive is not required for the operation of a computer. One could turn on a computer without a hard drive and load data from another device to operate it as normal. In the past, other devices have acted the part of semi-permanent storage, including floppy disks, magnetic tape, and punch cards.

Hard-Disk Drive

The major difference between RAM and HDDs

The main point to emphasize is the trade-off between cost and speed in the two technologies. RAM is much faster than a HDD (by orders of hundreds), but much more costly per unit of space. The introduction of SSDs has closed the speed gap somewhat (at the cost of price), but RAM is still the reigning champion between the two. Additionally, volatility is a major condition that affects what data we store in each type of memory. Although a hard drive is not needed to operate a computer, some type of non-volatile memory is required to make the computer useful. This is even true before the operating system (such as Windows, Linux, or OS X) loads. In fact, the initial power-on instructions are stored in a permanent location called CMOS in PCs and Firmware in Macs.

Memory: Why?

The prior section contains a basic description of storage in a computer, but the real reason to review it is to understand how each technology is utilized. Because RAM is fast, but volatile, it acts much like short-term memory in humans: the thought (program) is in the forefront of your mind (loaded in RAM), and you can quickly recall information (data) that took place (was stored on disk). Also like short-term memory, if we do not memorize it (commit it to long-term storage), the information is quickly forgotten (erased). Because information is so easily lost when stored in RAM, we are compelled to store important information on a more permanent medium. This is much like having a long-term memory: although the information is stored in your brain (on a hard drive) you can’t act on it (process it) until you actively recall it (read it from disk). Once you are cognizant of that thought (it exists in RAM), you can analyze (calculate) it, supplement (add data to) it, and re-store (save) that changed thought (file).

Wrap-up

If you think of hard drives as long-term memory and RAM as short-term memory, it becomes easy to understand how it isn’t possible to be actively thinking about every single piece of information you ever knew: Most people can only process a couple things at a time, and this is mostly true of computers.