What Do You Know About Computer Memory?

More than any other factor, such as disk space or processor speed, it is a computer's memory that determines how efficiently and how reliably it works. Even if you have a PC with a very fast processor, your software will still run slowly if you don't have enough memory installed. But what exactly is a computer's memory?

Computer memory is actually a pretty loose term. First of all, memory can refer to several different kinds of computer chip, each with its different uses. However, there is also a distinction between physical memory and virtual memory.

Virtual memory does not consist of real computer chips at all. Instead, it is simply a way of getting the software to pretend that it is using physical memory chips when, in fact, it is using part of your hard disk as a form of temporary storage. This provides a short term way in which to increase the available memory without having to install any extra chips.

The computer's physical memory chips come with various setups, designed to be installed inside your PC and other computer equipment, such as printers. These fall into a small number of different types, of which the most important is RAM (Random Access Memory). RAM is what people are usually referring to when they ask " How much memory does your PC have? " , RAM also known as main memory, RAM comes in the form of strips of computer chips that slot into the PC's motherboard. These are distinct from the processor's very high-speed cache memory chips.

You might expect memory to be a permanent quality, in the same way that humans will always remember the answer to two plus two, once they have learnt it. However, although devices such as your hard disk provide long term storage for this type of data, RAM is continually being overwritten and re-used by new data. RAM is more like the short term memory we use to remember a phone number we have just been told, until we can write it down.

RAM is used as a temporary storage area for all the information that your PC is dealing with from second to second. Although your hard disk is used for long term storage of all the data needed by your programs, it takes a while to find and load data from the disk. It is quicker if all the data you use is placed in RAM and accessed from there.

You can both read and write to RAM. This means that, as well as calling up the information held there, you can also put data back into it. However, this form of memory is what is known as 'volatile', meaning that it will be erased when you switch off your PC or if there is a problem with the power supply. This is why it is vital to save your work periodically, thus transferring the data you have just created and placed in RAM to permanent storage on the hard disk.