TUNIS

TUNIS, short for Toronto University System, is a Unix-like operating system developed at the University of Toronto in the early 1980s. It was portable and compatible with Unix Version 7, so programs that ran under Unix V7 could run under TUNIS without modification, but its kernel was completely redesigned and written in the Concurrent Euclid language. TUNIS was designed for teaching: it was meant to be a model of a well-structured, highly portable and easily understood Unix-like system. It used Concurrent Euclid modules to isolate machine dependencies and give a clean internal structure through information hiding, and it relied on that language's built-in processes and synchronization features to stay easy to understand and maintain. TUNIS targeted the PDP-11, the Motorola 6809 and 68000 and the National Semiconductor 32016, and it could be distributed across several processors using those same synchronization features.