1. Incompatible time-sharing SystemAn influential but highly idiosyncratic operating system written for the PDP-6 and PDP-10 at MIT and long used at the MIT AI Lab.Much AI-hacker jargon derives from ITS folklore, and to have been "an ITS hacker" qualifies one instantly as an old-timer of the most venerable sort.ITS pioneered many important innovations, including transparent file sharing between machines and terminal-independent I/O. After about 1982, most actual work was shifted to newer machines, with the remaining ITS boxes run essentially as a hobby and service to the hacker community.The shutdown of the lab' s last ITS machine in May 1990 marked the end of an era and sent old-time hackers into mourning nationwide (see high moby).The Royal Institute of Technology in Sweden is maintaining one "live" ITS site at its computer museum (right next to the only TOPS-10 system still on the Internet), so ITS is still alleged to hold the record for OS in longest continuous use (however, WAITS is a credible rival for this palm).2. A mythical image of operating system perfection worshiped by a bizarre, fervent retro-cult of old-time hackers and ex-users (see troglodyte).ITS worshipers manage somehow to continue believing that an OS maintained by {assembly language} hand-hacking that supported only monocase 6-character filenames in one directory per account remains superior to today' s state of commercial art (their venom against Unix is particularly intense).See also holy wars, Weenix.[Jargon File](1994-12-15)