Virtual Memory, built in all system versions since 7.5, is a combination of the RAM you have installed in your machine and a portion of your hard disk. The system uses this portion of your hard disk (called a partition) to store information. Your system needs to store data that it or programs that are running are using, it uses the area of your hard disk that has been set aside for that purpose. Your machine will run slower, since the computer must access the hard disk every time a program needs something that has been stored there, but it is acceptable for most Signalyze tasks. (This slow-down will be more noticeable on older machines.) Note that it also reduces the amount of your hard disk space that is available for saving files, a consideration with the smaller disks installed in older machines.

Before you turn on Virtual Memory, you should use a disk utility program to check and see if your disk is fragmented. If the disk you set up the Virtual Memory partition on is fragmented, performance could be quite slow. Click here for more information.

Open the Memory Control Panel (you should have an alias for the Control Panel Folder in your Apple Menu).

You will see something like the following inside the dialog:

1. Click on the On button (next to the arrow cursor in the figure above).
2. If you have more than one hard disk available, select the hard disk you want to use for the Virtual Memory partition using the popup menu (Select Hard Disk: in the figure above). The numbers below the popup menu will tell you how much memory is available on the hard disk that you select.
   
   If you only have one hard disk available, and the dialog tells you that there is not enough memory available to run Virtual Memory, you will need to increase the amount of disk space available on that disk before you enable Virtual Memory.
   
   
3. Set the size of the Virtual Memory to the total amount of memory you will be using (use the up and down arrow buttons, or type in a whole number). The recommended amount is twice the Available built-in memory amount--in the figure above, 64 MB.
4. Close the Memory dialog, and Restart the Mac for the changes to take effect.

When you Mac starts up, you will have the total amount of RAM available that you entered in the memory field.