Linus Torvalds Second Lieutenant, with the role of a ballistic calculation officer. Torvalds bought computer science professor Andrew Tanenbaum's book "", in which Tanenbaum describes MINIX, an educational stripped-down version of Unix. In 1990, he resumed his university studies, and was exposed to UNIX for the first time, in the form of a DEC MicroVAX running ULTRIX. His M.Sc. thesis was titled "Linux: A Portable Operating System". His interest in computers began with a Commodore VIC-20, at the age of 11 in 1981, initially programming in BASIC, but later by directly accessing the 6502 CPU in machine code. He did not make
Linux free software. Work began in 1984. Later, in 1985, Stallman started the Free Software Foundation and wrote the GNU General Public License (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed, although low-level elements such as device drivers, daemons, and the kernel, called GNU/Hurd, were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time (1991), he would not have decided to write his own. Although not released until