UNIX: Unix originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Douglas McIlroy, Joe Ossanna, and Tom Blakeley. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit organizations. MINIX: 1) MINIX was written for educational purposes by Professor Andrew S. Tanenbaum of Vrije Universiteit in Amsterdam 2) MINIX is a Unix-like computer operating system based on a microkernel architecture. 3) Released under the BSD license, MINIX is free and open source software.(1987) 4) Tanenbaum originally developed MINIX for compatibility with the IBM PC and IBM PC/AT microcomputers available at the time Features MINIX features a small, microkernel-based structure. A microkernel has a much smaller size than the commonly used monolithic kernels, and it usually provides only minimal services, such as defining memory address spaces, process management and interprocess communication (i.e., communication among currently active processes).