RT-11
Operating system
RT-11 is a discontinued small, low-end, single-user real-time operating system for the full line of Digital Equipment Corporation PDP-11 16-bit computers. RT-11 was first implemented in 1970. It was widely used for real-time computing systems,... Wikipedia
Initial release: 1973; 51 years ago
Programming languages: C, Assembly language, Fortran, and more
Default user interface: Keyboard Monitor (KMON) Command-line interface
Latest release: 5.7 / October 1998; 25 years ago
Source model: Closed source