A technique used by
virtual memory operating systems to help ensure that the
data you need is available as quickly as possible. The operating system
copies a certain number of
pages from your
storage device to
main memory. When a
program needs a page that is not in main memory, the operating system copies the required page into
memory and copies another page back to the
disk. One says that the operating system
pages the data. Each time a page is needed that is not currently in memory, a
page fault occurs. An
invalid page fault occurs when the address of the page being requested is invalid. In this case, the application is usually aborted.
This type of virtual memory is called paged virtual memory. Another form of virtual memory is segmented virtual memory.