Editing Memory segmentation (section)

{{Short description|The division of computer's primary memory into separately relocatable segments or sections}}
{{About|segmented computer memory|segments in object code|Object file}}
{{Use dmy dates|date=July 2022|cs1-dates=y}}
'''Memory segmentation''' is an [[operating system]] [[memory management (operating systems)|memory management]] technique of dividing a [[computer]]'s [[primary memory]] into '''segments''' or '''sections'''. In a [[computer architecture|computer system]] using segmentation, a reference to a memory location includes a value that identifies a segment and an [[offset (computer science)|offset]] (memory location) within that segment. Segments or sections are also used in [[object file]]s of compiled programs when they are [[linker (computing)|linked]] together into a [[program image]] and when the image is [[loader (computing)|loaded]] into memory.

Segments usually correspond to natural divisions of a program such as individual routines or data tables<ref name="holt1961"/> so segmentation is generally more visible to the programmer than [[paging]] alone.<ref name="englander"/> Segments may be created for program [[module (programming)|module]]s, or for classes of memory usage such as [[code segment]]s and [[data segment]]s.<ref name="glaser1965"/> Certain segments may be shared between programs.<ref name="holt1961"/><ref name="englander"/>

Segmentation was originally invented as a method by which [[system software]] could isolate software [[process (computing)|processes]] ([[task (computing)|tasks]]) and data they are using. It was intended to increase reliability of the systems running multiple processes simultaneously.<ref name=":0">{{cite book |url=https://www.amd.com/system/files/TechDocs/24593.pdf |title=AMD64 Technology AMD64 Architecture Programmer's Manual Volume 2: System Programming |publisher=Advanced Micro Devices |date=2018 |volume=2 |pages=5 |language=en |chapter=1.2 Memory Management}}</ref>