Virtual Memory related Terminology

Physical Address

An address in main memory.

Virtual Address

An address that corresponds to a location in virtual space and is translated by address mapping to a physical address when memory is accessed.


A virtual memory block is called a page.

Page Fault

An event that occurs when an accessed page is not present in main memory.

Page Table

The table containing the virtual to physical address translations in a virtual memory system. The table, which is stored in memory, is typically indexed by the virtual page number; each entry in the table contains the physical page number for that virtual page if the page is currently in memory.


Mechanism that allows the same program to run in any location in physical memory.


A set of mechanisms for ensuring that multiple processes sharing the processor, memory, or I/O devices cannot interfere, intentionally or unintentionally, with one another by reading or writing each other’s data. These mechanisms also isolate the operating system from a user process.

Address Translation/Mapping

The process by which a virtual address is mapped to an address used to access memory.

Context Switch

A changing of the internal state of the processor to allow a different process to use the processor that includes saving the state needed to return to the currently executing process.

Supervisor/Kernel Mode

A mode indicating that a running process is an operating system process.

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