SITS means "Small Incompatible Timesharing System". It was a timesharing operating system for a PDP-11/45, created in the mid-1970s at MIT for running Logo.
AI memo 356 has this blurb: During 1974-1975, our programming staff, under the direction or R. Lebel, completed the design and implementation of a general purpose multi-language timesharing system for the PDP-11/45. The SITS timesharing system was developed to provide an environment suitable for running Logo and other PDP-11/45 programs. It incorporates a Multics-like tree structured file system including (potentially) full access control. It also provides unique capabilities for running programs as multiple process systems, rather than the more common single process approach, and the ability for each user to run many jobs simultaneously. The system include provisions for using both the older refreshed displays and our new raster displays.
Type ./build.sh to install SITS from binaries in the bin directory.
The binaries were cross assembled from ITS. The automated scripts
will format disks and install a basic system using paper tapes.
The SIMH emulator is compiled from source code; it may need some dependencies installed first.
Type ./run.sh to run SITS. Several windows will be opened which
represent teletypes, vector displays, and raster displays.
Type ^Z to a teletype to log in, or Escape on a TV display. Log in as
GUEST. Type : 0; . SLOGO to run Logo.
Useful commands in DDT are :HELP to see a list of commands, :SETD
to set the current directory, :LISTF to list files, and :LOGOUT to
log out. See the DDTORD file for more information.
Useful commands in Logo include CLEARSCREEN to start turtle
graphics, and GOODBYE to log out. The 1974 AI memo 313
documents a slightly older version.
There are several different displays available:
- To use a TV display, log in on a TV and type
CS. - To use a vector display, log in on TTY 1 and type
CS. - To use the 2500, log in on the 2500 TV display and type
GTLDIS.