'''Multics''' operativsystem ('''Mult'''ipleksede '''I'''nformation og '''C'''omputing '''S'''ervice) var forløberen til [[UNIX]] og andre moderne operativsystemer.<ref name="multicians">[https://multicians.org/ multicians.org: Multics] Citat: "...Multics (Multiplexed Information and Computing Service) was a mainframe time-sharing operating system begun in 1965 and used until 2000. Multics began as a research project and was an important influence on operating system development...", [https://web.archive.org/web/20211103123642/https://multicians.org/ backup]</ref>
Multics, som startede i [[1964]], var et baneførende time-sharing operativsystem som blev udviklet i et projekt med deltagelse af flere af samtidens store koncerner: [[MITMassachusetts Institute of Technology|(MitchiganMassachusetts Institute of Technology]] (MIT), [[GE|General Electric]] og [[Bell Labs]] indførte en lang række nye koncepter, f.eks. [[dynamisk linking]] og en [[hierarkiske filsystemer]]. Det var ekstremt magtfuldt, og UNIX kan (med lidt god vilje) anses for at være en "fornyet" efterfølger til Multics. (Navnet "Unix" er i sig selv en afledning af "Multics").<ref name="multiciansHistory">[https://multicians.org/history.html multicians.org: History] Citat: "...Multics ran on specialized expensive mainframe hardware whose CPU provided a segmented, paged, ring-structured virtual memory. The supervisor implemented symmetric multiprocessing with shared physical and virtual memory. Standard Honeywell mainframe peripherals and memory were used. The operating system was programmed in PL/I...While I felt that the rest of the committee was leaning towards recommending termination, I began to realize that killing off Multics was a terrible idea. My reasoning was as follows: While the Multics project might have been overly ambitious, it was the sole embodiment a great number of very important ideas. The current efforts were taking advantage of lessons learned; knowledge and experience available nowhere else on the planet. If we killed off Multics, it was likely that these ideas would become lost art and would be discredited along with the whole Multics project; all to the possible detriment of many future projects. I decided that the committee had to come to the opposite conclusion to the one that Lick expected...", [https://web.archive.org/web/20211104153041/https://multicians.org/history.html backup]</ref>
Multics havde en hård start med store krav, fra interessenterne, til funktionaliteten kombineret med krav om økonomisk gevinst. Hertil kommer at programmørerne erfarede at man rent teknisk havde slået et "for stort brød op". idet nogle funktioner var så omfattende at man måtte midlertidigt erstatte dem med mindre. Det gav problemer med opdateringen af manualerne som man var begyndt på, mens man afventede på, at compilerne skulle færdiggøres. År 1968-1969 var Multics-projektet tæt på at blive afviklet.<ref name="multiciansHistory"/>
