Wizard's Place

There are several types of computer memory which really includes things like floppy discs and hard drives but on this page we are going to talk about the two basic types of memory inside the computer, random access memory (RAM) and read only memory (ROM). These types of memory are often called memory chips — not the kind served with salt and vinegar; these wouldn’t test very good. Memory chips look something like this:

Individual chips (the black rectangles in the picture above) are often attached to cards with a connector edge that fits into special slots on the main circuit board, often called the mother board inside the computer box or portable case. These cards can be changed to upgrade the amount of memory your computer has.

Sometimes these memory chips are fixed permanently (soldered) to the mother board or to other circuit cards withing the computer housing. Sometimes they are located in other devices; keyboard, monitor, even the mouse.

Computer memory is a little like our own memory. Just as we store thoughts in our memory, some for short term use, some for long term, in the same way computers use memory chips to store information.

Read Only Memory (ROM) has the information permanently written to it. In many ways this is like a printed book. You can go back to the book to read it as many times as you want but you can’t move the individual letters or words around.

Random Access Memory (RAM) is more like a white board written on with erasable markers. You can write on it and what you write will stay until it is erased and then you can write again. When we talk about memory in a computer we are most often talking about RAM. Many novices think the amount of memory their computer has is the size of their hard drive. This is actually true, as we’ll see on another page, but it is not what computer professionals are usually talking about when they say memory.

The amount of memory your computer has will have a lot to do with how much work it can do, what size of programs it can run, and how fast it will be. These days most newer computers need at least two gigabytes (two billion characters) of memory storage of the type known as RAM. Four gigabytes is not uncommon even for general home and small business use and eight gigabytes or more can be needed for playing modern action games or working with extensive graphics.

If your computer regularly runs slow, locks up for short periods, or even stops working completely it is less likely you have a virus and most likely you don’t have enough RAM.

If you upgrade from an earlier version of Windows (XP for example) to a newer version (Vista or Windows 7) on the same computer without adding more RAM you may well have problems with the operation of the computer. Newer operating systems, developed for newer computers, expect to find more RAM available for them to use.

The good news is RAM has become very cheap to acquire.

When you do something with your computer you are generally using a program; a set of instructions that tells the computer what to do. The browser you are using to read this page is a program. The word process you may use to write a letter, a short story, or even a novel, is a program. When you read your email you are using a program.

When a computer uses a program it loads all or part of it into RAM so it can read it and work with it. When you enter information into the program; a URL into your browser address bar, a search term into Google, an email to your friend, etc. that information is written to RAM. It stays in RAM as long as it is being used.

If you open more than one program at a time of if your individual program opens more than one window at a time (like pop-ups when browsing on a website) then your computer uses more RAM. It all adds up pretty quickly.

If you are writing a novel, for example, you probably save it as a file on your hard drive. The novel may be too big for your computer to load it all in RAM at once. As you scroll through the pages in your word processor your computer will unload the pages you have looked at and load the next pages that are coming up.

When a program itself is too big to keep in RAM your computer will only load the parts, the immediate set of instructions, it needs.

If your computer needs to work with larger files and you don’t have enough RAM it can set aside part of your hard drive and treat it like RAM. We call this virtual ram or swap space. Your computer swaps blocks of information or program code in and out of this space, and into RAM, as needed. This is faster than loading the actual file saved on the hard drive because of the way files are stored (see the page on hard drives) but much slower than using just RAM itself.

If your computer is generally slow and pauses or locks up a lot during use, or if your hard drive is often active when you are not actually saving or opening files, you may not have enough RAM.