FreeBSD 8.1 CD, 1 disc set.

FreeBSD is a UN*X-like operating system for the i386, IA-64, PC-98, Alpha/AXP, and UltraSPARC platforms based on U.C. Berkeley's "4.4BSD-Lite" release, with some "4.4BSD-Lite2" enhancements. It is also based indirectly on William Jolitz's port of U.C. Berkeley's "Net/2" to the i386, known as "386BSD", though very little of the 386BSD code remains. FreeBSD is used by companies, Internet Service Providers, researchers, computer professionals, students and home users all over the world in their work, education and recreation.

Link: http://www.freebsd.net