Minix on the Net Informations area provides ...
About Minix: Minix is a small operating system that is very similar to UNIX. A small UNIX clone developed for educational purposes. It has been written from scratch, and therefore does not contain any AT&T code--not in the kernel, the compiler, the utilities, or the libraries. For this reason it can be made available with complete source code. Minix was originally developed by Andrew Tanenbaum as a tool for teaching operating systems principles. The current version of Minix is described in detail in the text Operating Systems: Design and Implementation, 2nd edition, written by Tanenbaum and Albert Woodhull.