Operating system: Difference between revisions

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There are three main purposes that an operating system fulfills:{{sfn|Anderson|Dahlin|2014|p=7}}

*Operating systems allocate resources between different applications, deciding when they will receive [[central processing unit]] (CPU) time or space in [[computer memory|memory]].{{sfn|Anderson|Dahlin|2014|p=7}} On modern [[Personalpersonal computer|personal computers]]s, users often want to run several applications at once. In order to ensure that one program cannot monopolize the computer's limited hardware resources, the operating system gives each application a share of the resource, either in time (CPU) or space (memory).{{sfn|Anderson|Dahlin|2014|pp=9–10}}{{sfn|Tanenbaum|Bos|2023|pp=6-7}} The operating system also must isolate applications from each other to protect them from errors and security vulnerabilities in another application's code, but enable communications between different applications.{{sfn|Anderson|Dahlin|2014|p=10}}

*Operating systems provide an interface that abstracts the details of accessing [[Computer hardware|hardware]] details (such as physical memory) to make things easier for programmers.{{sfn|Anderson|Dahlin|2014|p=7}}{{sfn|Tanenbaum|Bos|2023|p=5}} [[Virtualization]] also enables the operating system to mask limited hardware resources; for example, [[virtual memory]] can provide a program with the illusion of nearly unlimited memory that exceeds the computer's actual memory.{{sfn|Anderson|Dahlin|2014|p=11}}

*Operating systems provide common services, such as an interface for accessing network and disk devices. This enables an application to be run on different hardware without needing to be rewritten.{{sfn|Anderson|Dahlin|2014|pp=7, 9, 13}} Which services to include in an operating system varies greatly, and this functionality makes up the great majority of code for most operating systems.{{sfn|Anderson|Dahlin|2014|pp=12–13}}

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If an application is written for use on a specific operating system, and is [[ported]] to another OS, the functionality required by that application may be implemented differently by that OS (the names of functions, meaning of arguments, etc.) requiring the application to be adapted, changed, or otherwise [[software maintenance|maintained]].<!--There really ought to be a discussion of ''software modules'' somewhere, such as those that are neither API's nor Plug-Ins (not sure what those are), but which are either hard (on cartridge), soft (on diskette), or otherwise installable by downloading). -->

This cost in supporting operating systems diversity can be avoided by instead writing applications againstfor [[software platform]]s such as [[Java (software platform)|Java]] or [[Qt (software)|Qt]]. These abstractions have already borne the cost of adaptation to specific operating systems and their [[system library|system libraries]].

Another approach is for operating system vendors to adopt standards. For example, [[POSIX]] and [[operating system abstraction layer|OS abstraction layers]] provide commonalities that reduce porting costs.

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* {{cite book | last = Bic| first = Lubomur F. |author2=Shaw, Alan C. | title = Operating Systems | publisher = [[Prentice Hall]] | year = 2003 | ___location = Pearson }}

* {{cite book | last = Silberschatz | first = Avi |author2=Galvin, Peter |author3=Gagne, Greg | title = Operating Systems Concepts | publisher = [[John Wiley & Sons]] | year = 2008 | isbn = 978-0-470-12872-5 }}

* {{cite book |last1=O'Brien, |first1=J. A., & |last2=Marakas, |first2=G. M.( |date=2011). ''|title=Management Information Systems''. 10e.|edition=10th |publisher=McGraw-Hill Irwin.}}

* {{cite book |last1=Leva |first1=Alberto |last2=Maggio |first2=Martina |last3=Papadopoulos |first3=Alessandro Vittorio |last4=Terraneo |first4=Federico |title=Control-based Operating System Design |publisher=[[Institution of Engineering and Technology|IET]] |year=2013 |isbn=978-1-84919-609-3}}

*{{cite journal |last1=Richet |first1=Jean-Loup |last2=Bouaynaya |first2=Wafa |title=Understanding and Managing Complex Software Vulnerabilities: An Empirical Analysis of Open-Source Operating Systems |journal=Systèmes d'information & management |date=2023 |volume=28 |issue=1 |pages=87–114 |doi=10.54695/sim.28.1.0087 |doi-broken-date=112 NovemberJuly 20242025 |url=https://www.cairn.info/revue-systemes-d-information-et-management-2023-1-page-87.htm.}}

*{{cite book |last1=Silberschatz |first1=Abraham |last2=Galvin |first2=Peter B. |last3=Gagne |first3=Greg |title=Operating System Concepts |date=2018 |publisher=Wiley |isbn=978-1-119-32091-3 |edition=10 |url=https://archive.org/details/operating-system-concepts-10th |language=en-us|ref={{sfnref|Silberschatz et al.|2018}}}}

*{{cite book |last1=Tanenbaum |first1=Andrew S. |last2=Bos |first2=Herbert |title=Modern Operating Systems, Global Edition |date=2023 |publisher=Pearson Higher Ed |isbn=978-1-292-72789-9 |language=en}}