Multics

(operating system)/muhl'tiks/ MULTiplexed Information andComputing Service. A time-sharing operating systemco-designed by a consortium including MIT, GE and Bell Laboratories as a successor to MIT's CTSS. The systemdesign was presented in a special session of the 1965 FallJoint Computer Conference and was planned to be operational intwo years. It was finally made available in 1969, and tookseveral more years to achieve respectable performance andstability.

Multics was very innovative for its time - among other things,it was the first major OS to run on a symmetric multiprocessor; provided a hierarchical file system withaccess control on individual files; mapped files into apaged, segmented virtual memory; was written in ahigh-level language (PL/I); and provided dynamicinter-procedure linkage and memory (file) sharing as thedefault mode of operation. Multics was the onlygeneral-purpose system to be awarded a B2 security rating bythe NSA.

Bell Labs left the development effort in 1969. Honeywellcommercialised Multics in 1972 after buying out GE's computergroup, but it was never very successful: at its peak in the1980s, there were between 75 and 100 Multics sites, each amulti-million dollar mainframe.

One of the former Multics developers from Bell Labs was Ken Thompson, a circumstance which led directly to the birth ofUnix. For this and other reasons, aspects of the Multicsdesign remain a topic of occasional debate among hackers. Seealso brain-damaged and GCOS.

MIT ended its development association with Multics in 1977.Honeywell sold its computer business to Bull in the mid1980s, and development on Multics was stopped in 1988 whenBull scrapped a Boston proposal to port Multics to aplatform derived from the DPS-6.

A few Multics sites are still in use as late as 1996.

The last Multics system running, the Canadian Department ofNational Defence Multics site in Halifax, Nova Scotia, Canada,shut down on 2000-10-30 at 17:08 UTC.

The Jargon file 3.0.0 claims that on some versions ofMultics one was required to enter a password to log out butJames J. Lippard , who was a Multicsdeveloper in Phoenix, believes this to be an urban legend.He never heard of a version of Multics which required apassword to logout. Tom Van Vleck agrees. He suggests that some user may have implemented a'terminal locking' program that required a password before onecould type anything, including logout.

http://multicians.org/.

Usenet newsgroup: news:alt.os.multics.

MULTICS

(MULTiplexed Information and Computing Service) Developed at MIT and Bell Labs in the mid-1960s, MULTICS was the first timesharing operating system. It was also one of the first to implement symmetric multiprocessing. Used on GE's mainframes, which were absorbed into the Honeywell product line, MULTICS was later acquired by Bull.