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operating system /muhl'tiks/ MULTiplexed Information and
Computing Service. A time-sharing operating system
co-designed by a consortium including MIT, GE and BellLaboratories as a successor to MIT's CTSS. The system
design was presented in a special session of the 1965 Fall
Joint Computer Conference and was planned to be operational in
two years. It was finally made available in 1969, and took
several more years to achieve respectable performance and
Multics was very innovative for its time - among other things,
it was the first major OS to run on a symmetricmultiprocessor; provided a hierarchical file system with
access control on individual files; mapped files into a
paged, segmented virtual memory; was written in a
high-level language (PL/I); and provided dynamic
inter-procedure linkage and memory (file) sharing as the
default mode of operation. Multics was the only
general-purpose system to be awarded a B2 security rating by
the NSA.
Bell Labs left the development effort in 1969. Honeywell
commercialised Multics in 1972 after buying out GE's computer
group, but it was never very successful: at its peak in the
1980s, there were between 75 and 100 Multics sites, each a
multi-million dollar mainframe.
One of the former Multics developers from Bell Labs was KenThompson, a circumstance which led directly to the birth of
Unix. For this and other reasons, aspects of the Multics
design remain a topic of occasional debate among hackers. See
MIT ended its development association with Multics in 1977.
Honeywell sold its computer business to Bull in the mid
1980s, and development on Multics was stopped in 1988 when
Bull scrapped a Boston proposal to port Multics to a
platform 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 of
National 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 of
Multics one was required to enter a password to log out but
James J. Lippard [email protected], who was a Multics
developer in Phoenix, believes this to be an urban legend.
He never heard of a version of Multics which required a
password to logout. Tom Van Vleck [email protected]
agrees. He suggests that some user may have implemented a
'terminal locking' program that required a password before one
could type anything, including logout.