page fault

In computer storage technology, a page is a fixed length block of memory that is used as a unit of transfer between physical memory and external storage like a disk, and a page fault is an interrupt (or exception) to the software raised by the hardware, when a program accesses a page that is mapped in address space, but not loaded in physical memory.
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<memory management> In a paged virtual memory system, an access to a page (block) of memory that is not currently mapped to physical memory. When a page fault occurs the operating system either fetches the page in from secondary storage (usually disk) if the access was legitimate or otherwise reports the access as illegal.
(1995-11-11)