Editing Incompatible Timesharing System (section)

==History==
ITS development was initiated in the late 1960s by those (the majority of the MIT AI Lab staff at that time) who disagreed with the direction taken by Project MAC's [[Multics]] project (which had started in the mid-1960s), particularly such decisions as the inclusion of powerful [[computer security|system security]]. The name was chosen by [[Tom Knight (scientist)|Tom Knight]] as a joke on the name of the earliest MIT time-sharing operating system, the [[Compatible Time-Sharing System]] (CTSS), which dated from the early 1960s.<ref name=LevyWL>{{cite book|last1=Levy|first1=Steven|title=Hackers: Heroes of the Computer Revolution - 25th Anniversary Edition|url=https://archive.org/details/hackersheroescom00levy_989|url-access=limited|date=2010|publisher=[[O'Reilly Media]]|location=Sebastopol, CA|isbn=978-1449388393|pages=[https://archive.org/details/hackersheroescom00levy_989/page/n102 85]–102|edition=1st|chapter=Winners and Losers}}</ref>

By simplifying their system compared to Multics, ITS's authors{{who|date=February 2025}} were able to quickly{{Clarify|reason=vague|date=May 2016}} produce a functional operating system for their lab.<ref name="stuart">{{cite book |title=Principles of Operating Systems: Design & Applications |first=Brian L. |last=Stuart |publisher=Cengage Learning EMEA |year=2008 |page=23 |isbn=9781300668558 |oclc=221248143 }}</ref><!-- I don't have a copy of this book, but the table of contents has CTSS not ITS. I guess I could use a library. --> ITS was written in [[assembly language]], originally for the [[Digital Equipment Corporation]] [[PDP-6]] computer, but the majority of ITS development and use was on the newer, largely [[Forward compatibility|upwards-compatible]], [[PDP-10]].<ref name="LevyWL" />

Although not used as intensively after about 1986, ITS continued to operate on original hardware at MIT until 1990, and then until 1995 at {{ill |Stacken Computer Club|sv|Stacken}} in Sweden. Today, some ITS implementations continue to be remotely accessible, via [[Emulator|emulation]] of PDP-10 hardware running on modern, low-cost computers supported by interested hackers.