MINIX. Particularly for this reason "Years later, I was teaching a course on operating systems and using John Lions' book on UNIX Version 6. When AT&T decided

MINIX. Particularly for this reason "Years later, I was teaching a course on operating systems and using John Lions' book on UNIX Version 6. When AT&T decided to forbid the teaching of the UNIX internals, I decided to write my own version of UNIX, free of all AT&T code and restrictions, so I could teach from it." Source: http://www.cs.vu.nl/~ast/brown/ http://www.cs.vu.nl/~ast/brown/