
Hard disks, though cheap, are much slower than physical memory, so we hope that we are only
storing rarely used sections of the code on the disk. Figuring out which sections of code can easily be
parceled out to RAM rather than to the hard disk can be a job either for the OS designer or for the
conscientious application designer who wants her program to run very quickly.
NEED TO
KNOW…A NOTE ON TERMINOLOGY
Strictly speaking, you can have a virtual memory system without using your hard disk for
memory at all. All a virtual memory system does is map real memory addresses to artificial
memory addresses that are presented to the application. In practice, ...