17 Facts About Multics


Multics is an influential early time-sharing operating system based on the concept of a single-level memory.

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Nathan Gregory writes that Multics "has influenced all modern operating systems since, from microcomputers to mainframes.

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Multics has numerous features intended to ensure high availability so that it would support a computing utility similar to the telephone and electricity utilities.

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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.

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In POSIX terminology, it is as if every file were mmaed; however, in Multics there is no concept of process memory, separate from the memory used to hold mapped-in files, as Unix has.

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Multics is the first major operating system to be designed as a secure system from the outset.

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Multics is the first operating system to provide a hierarchical file system, and file names can be of almost arbitrary length and syntax.

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Multics is the first to use the now-standard concept of per-process stacks in the kernel, with a separate stack for each security ring.

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In 1964, Multics was developed initially for the GE-645 mainframe, a 36-bit system.

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GE's computer business, including Multics, was taken over by Honeywell in 1970; around 1973, Multics is supported on the Honeywell 6180 machines, which included security improvements including hardware support for protection rings.

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At MIT in 1975, use of Multics was declining and did not recover by 1976 to prior levels.

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In 1985, Multics was issued certification as a B2 level secure operating system using the Trusted Computer System Evaluation Criteria from the National Computer Security Center a division of the NSA, the first operating system evaluated to this level.

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Multics was distributed from 1975 to 2000 by Groupe Bull in Europe, and by Bull HN Information Systems Inc in the United States.

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In 2014, Multics was successfully run on current hardware using an emulator.

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Peter H Salus, author of a book covering Unix's early years, stated one position: "With Multics they tried to have a much more versatile and flexible operating system, and it failed miserably".

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Design and features of Multics slightly influenced the Unix operating system, which was originally written by two Multics programmers, Ken Thompson and Dennis Ritchie.

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The high-reliability, availability, and security features of Multics were extended in Stratus VOS to support a new line of fault tolerant computer systems supporting secure, reliable transaction processing.

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