SITS

SITS - Small ITS - was a time-sharing operating system for a PDP-11/45, created in the mid-1970s at MIT for running Logo. Its design is vaguely reminiscent of ITS, with large influences from MIT's PDP-1X Time Sharing System. Like ITS, there is a resident kernel debugger (called RUG); SALV for managing disks; TECO for text editing, and DDT for debugging and running user programs. Processes can be PCLSR'ed just like in ITS. From the PDP-1X it inherited capability-based security and the concept of spheres. It has a hierarchical tree-structured file system inspired by Multics. SITS supported raster displays similar to those used with the AI lab Knight TV, a few vector displays, and General Turtle 2500 terminals.