Page Table

Difference Between Paging and Segmentation

Paging divides memory into fixed-size blocks called pages (mapped to equal-size frames in physical memory), while segmentation divides memory into variable-siz…

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 Demand Paging?

Demand paging is a virtual memory technique where a page is loaded into physical memory only when a process actually references it, rather than loading the who…

What is a Translation Lookaside Buffer (TLB)?

A Translation Lookaside Buffer, or TLB, is a small, fast hardware cache inside the CPU that stores recent virtual-to-physical address translations, so the MMU…

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 Copy-on-Write (COW)?

Copy-on-write is an optimization where two entities share the same underlying physical memory pages read-only until one of them attempts to modify the data, at…

What is Segmentation with Paging?

Segmentation with paging is a hybrid memory management scheme where a process's address space is first divided into logically meaningful, variable-sized segmen…

What is Associative Memory (Content-Addressable Memory)?

Associative memory, also called content-addressable memory (CAM), is memory that is searched by comparing a given value against all stored entries in parallel…

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 is the Reference Bit in Paging?

The reference bit (also called the accessed bit) is a single flag in each page table entry that the hardware sets whenever a page is read or written, giving th…

What is Pure Demand Paging?

Pure demand paging is a memory management policy where absolutely no page of a process is loaded into RAM until the process actually references it, so every pr…

What are the Tradeoffs of Page Size?

Choosing a larger page size reduces page table size and TLB pressure and improves transfer efficiency for large sequential reads, while choosing a smaller page…

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…