From LXF Wiki
Minix, developed in the late 1980s by Andrew Tannenbaum, was designed as a small Unix-like operating system, used for teaching purposes. Today, some people still run Minix on machines such as Atari STs, so mad props to them.
We also have Andrew to thank for Linux. Linus Torvalds tells in his autobiography how he was frustrated by limitations in Minix, but Andrew would not let him fix the (proprietary) source code. So Linus was forced to do it the hard way and start from scratch. This experience was a strong factor in Linus' choice of the GPL when he came to unleash the end result - Linux - on the world. Nice one, Andrew!