MMU

What is Virtual Memory?

Virtual memory is a technique that gives each process the illusion of a large, private, contiguous address space by mapping virtual addresses to physical RAM (…

What is a Page Fault?

A page fault is a hardware trap raised by the MMU when a running program accesses a virtual memory page that is not currently mapped to a physical frame, forci…

What is the Structure of a Page Table?

A page table is a per-process data structure maintained by the operating system that maps virtual page numbers to physical frame numbers, with each entry also…

What is a Multilevel Page Table?

A multilevel page table splits a single flat page table into a hierarchy of smaller tables, where the virtual address is broken into multiple index fields that…

What is an Inverted Page Table?

An inverted page table flips the usual mapping direction by keeping one entry per physical frame instead of one entry per virtual page, storing which process a…

What is the Dirty Bit in Paging?

The dirty bit (also called the modified bit) is a single flag in each page table entry that the hardware sets whenever a process writes to that page in memory,…

What are Memory Protection Mechanisms?

Memory protection mechanisms are hardware- and OS-enforced controls -- base/limit registers, per-page permission bits, and separate virtual address spaces -- t…

What is Address Binding?

Address binding is the process of mapping the logical addresses a program uses -- its symbols, variables, and instruction references -- onto actual memory addr…

Logical vs Physical Address in Operating Systems

A logical address is the address a running program generates and sees, relative to its own address space, while a physical address is the real hardware locatio…