Editing Multics (section)

{{Short description|Time-sharing operating system}}
{{Use mdy dates|date=February 2015}}
{{Infobox OS
| name = Multics
| logo = Multics-logo.svg
| logo_size = 128px
| screenshot = Multics-Login.png
| caption = Login screen for the BAN.AI public Multics server
| developer = [[Massachusetts Institute of Technology|MIT]], [[General Electric|GE]], [[Honeywell International, Inc.|Honeywell]], [[Bell Labs]]
| prog_language = 
| programmed_in = [[PL/I]], [[Assembly language]]<ref name="Mpl1" />
| family = <!-- [[Unix]] ? -->
| working_state = Mature, current, historic, emulator available
| source_model = [[Open source]]
| released = {{Start date and age|1969}}
| latest_release_version = 12.8
| latest_release_date = {{Start date and age|2023|08|10}}
| latest_test_version = 
| latest_test_date = 
| marketing_target = 
| language = [[English language|English]]
| updatemodel = 
| package_manager = 
| supported_platforms = [[GE-645]], [[Honeywell 6000 series]] machines ([[Honeywell 6180]], Series-60/Level-68, DPS-8/M mainframes)
| kernel_type = [[Monolithic kernel]]
| ui = [[Command-line interface]]
| license = Originally [[proprietary software|proprietary]],<br />Free software Multics License since 2007<ref>{{cite web|url=http://opensource.org/licenses/Multics|title=Multics License (Multics) - Open Source Initiative|website=opensource.org|date=February 5, 2008 |access-date=April 11, 2018}}</ref><ref name="myths">{{cite web|url=http://www.multicians.org/myths.html#source|title=Myths about Multics|website=www.multicians.org|access-date=April 11, 2018}}</ref>
| preceded by = [[Compatible Time-Sharing System]]
| influenced = [[Unix]], [[GEORGE (operating system)|GEORGE 3]], [[ICL VME]], [[PRIMOS]], [[Domain/OS]], [[Stratus VOS]]
| website = {{URL|multics-wiki.swenson.org}}
}}
'''Multics''' ("'''MULTiplexed Information and Computing Service'''") is an influential early [[time-sharing]] [[operating system]] based on the concept of a [[single-level store|single-level memory]].<ref name="Ritchie84">Dennis M. Ritchie, "The Evolution of the Unix Time-sharing System", Communications of the ACM, Vol. 17, 1984, pp. 365-375.</ref><ref>{{cite web|url=http://tenex.opost.com/hbook.html|title=Origins and Development of TOPS-20|author=Dan Murphy|year=1996|orig-year=1989}}</ref> It has been written that Multics "has influenced all modern operating systems since, from microcomputers to mainframes."<ref>{{cite book |last1=Gregory |first1=Nathan |title=The Tym Before |date=May 2018 |publisher=Lulu.com |isbn=9781387824755 |page=66 |url=https://books.google.com/books?id=kn9eDwAAQBAJ&q=page%2066 |access-date=Mar 29, 2020}}</ref>

Initial planning and development for Multics started in 1964, in [[Cambridge, Massachusetts]]. Originally it was a cooperative project led by [[Massachusetts Institute of Technology|MIT]] ([[Project MAC]] with [[Fernando Corbató]]) along with [[General Electric]] and [[Bell Labs]]. It was developed on the [[GE 645]] computer, which was specially designed for it; the first one was delivered to MIT in January 1967. GE offered their earlier 635 systems with the [[Dartmouth Time-Sharing System]] which they called "Mark I" and intended to offer the 645 with Multics as a larger successor. Bell withdrew from the project in 1969 as it became clear it would not deliver a working system in the short term. Shortly thereafter, GE decided to exit the computer industry entirely and sold the division to [[Honeywell]] in 1970. Honeywell offered Multics commercially, but with limited success.

Multics has numerous features intended to ensure high availability so that it would support a [[computing utility]] similar to the [[telephone]] and [[electricity]] [[public utility|utilities]]. Modular hardware structure and software architecture are used to achieve this. The system can grow in size by simply adding more of the appropriate resource, be it computing power, main memory, or disk storage. Separate [[access control list]]s on every file provide flexible information sharing, but complete privacy when needed. Multics has a number of standard mechanisms to allow engineers to analyze the performance of the system, as well as a number of adaptive performance optimization mechanisms.

Due to its many novel and valuable ideas, Multics has had a significant influence on [[computer science]] despite its faults.<ref name="Myths about Multics">{{cite web|url=http://www.multicians.org/myths.html|title=Myths about Multics|website=www.multicians.org|access-date=April 11, 2018}}</ref> Its most lasting effect on the computer industry was to  inspire the creation of [[Unix]], which carried forward many Multics features, but was able to run on less-expensive hardware. Unix was developed at Bell to allow their Multics team to continue their research using smaller machines, first a [[PDP-7]] and ultimately the [[PDP-11]].