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MMU

The hardware unit that translates the addresses a program uses into real physical memory locations.

Every program runs believing it has its own clean range of memory (virtual addresses); the Memory Management Unit translates those on the fly into actual physical addresses using per-process page tables. This is what keeps processes isolated from each other and lets the OS control who can touch what. When a translation is missing or forbidden, the MMU raises a page fault for the OS to handle.

See also

  • page tableThe lookup structure the CPU uses to map a program's virtual addresses to real physical memory.
  • pagingThe virtual-memory scheme that splits memory into fixed-size chunks and maps them flexibly.
  • page faultThe interrupt that fires when a program touches memory that isn't currently mapped in.

Referenced by

MMIO / memory-mapped I/O · page fault · page table · paging · PC (program counter)