Virtual Memory is used when your PC runs out of RAM. This happens more on a computer with a low amount of RAM trying to run demanding software or too many programs at once. When the RAM limit is reached, the hard disk is then used as virtual memory effectively giving you double or more the amount of RAM. However, the downside is that Virtual Memory tends to slow the PC down because it pages to the hard drive which is a lot slower then your RAM.
When was Virtual Memory introduced?
Virtual memory was first introduced in the late 1950s and early 1960s when computers were fairly new. The Windows OS has been running virtual memory since 1990 when Windows 3.0 was released. It was introduced to drop the amount of expensive RAM needed to keep the PC running.
How much Virtual Memory do I have?
As a default in Windows the amount of virtual memory is configured at 1.5x for the minimum setting going up to 3x maximum. If you need more then this you can manually adjust the settings.
How can I change the Virtual Memory setting?
If running Windows XP, you right click My Computer > Properties > Advanced > Settings (Under the performance section) > Advanced > Change (Under the virtual memory section). In this section you will see various variables you can set to specify how much virtual memory you would like. Leaving everything as default is usually ok.
Downsides of using Virtual Memory
The downside of using virtual memory is that it slows your PC down. When your RAM is full and the programs are accessing the extra RAM on the hard drive it takes a lot longer to retrieve the data it needed because hard drives are far slower then RAM.
Upgrading
If you find that your PC is running slow and can constantly hear the hard drive clicking away then the best thing to usually do is upgrade the RAM. This will allow more programs to run in RAM rather then virtual memory and should keep the PC running nicely.
How much RAM is good?
If running Windows XP then 512Mb is the minimum I would recommend and 1Gb being ideal. For Vista I would recommend looking at 1Gb as the minimum amount if you want all the special screen effects.
