Memory management unit

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A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit that examines all references to memory, and translates the memory addresses being referenced, known as virtual memory addresses, into physical addresses in main memory. In modern systems, programs generally have addresses that access the theoretical maximum memory of the computer architecture, 32 or 64 bits. The MMU maps the addresses from each program into separate areas in physical memory, which is generally much smaller than the theoretical maximum. This is possible because programs rarely use large amounts of memory at any one time. Most modern operating systems (OS) use an MMU to provide virtual memory (VM) support. The MMU tracks memory use in fixed-size blocks known as pages. If a program refers to a location in a page that is not in physical memory, the MMU sends an interrupt to the operating system. The OS selects a lesser-used block in memory, writes it to backing...

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