Andrew Stuart "Andy" Tanenbaum (sometimes referred to by the handle ast) (born March 16, 1944) is an American computer scientist and professor emeritus of computer science at the Vrije Universiteit, Amsterdam in the Netherlands.He is best known as the author of MINIX, a free Unix-like operating system for teaching purposes, and for his computer science textbooks, regarded as standard texts in the field. He regards his teaching job as his most important work.