ACM Crossroads: Operating Freely Description of the 3 major, freely available, Unix-like operating systems: Linux, FreeBSD, NetBSD. Crossroads is the student magazine of the ACM. http://www.acm.org/crossroads/xrds1-3/free.html

Open Source Unix and Related Software Projects Small page of logos and links to resources, distribution channels for the most popular, freely distributable Unix, and a few other projects. FREENIX links in English, Français, Norsk. http://www.opensourceunix.com/

COTSE-Mini UNIX Distributions Links to 2 dozen mini Unix distributions: mostly Linux, also FreeBSD, SCO, Solaris MINIX, MINIX. http://www.cotse.com/miniunix.htm

PIOS: Pleasant Interactive Operating System Free Unix clone developed by PIE Software Inc., for x86 PC compatibles, to give a stable multi-user high security platform for use as a network server, programming work-horse, or desktop system; designed so even complex tasks are easy. http://www.piesoftwareinc.co.uk/

Linux and BSD, Open Source Giants Succinct, clear, non-technical introduction to Linux and BSD, focus: how they are relevant to business. http://shearer.org/en/writing/whatarelinuxbsd.html

Thix Unix kernel written in 1994-95; almost full implementation of POSIX.1 standard, IEEE Std 1003.1-1988. Goal: mainly to learn OS design, architecture, kernel algorithms, resource allocation, process scheduling, and memory management; free software has been compiled for it. [Open Source, GPL] http://www.hulubei.net/tudor/thix/

Wind River Systems, Inc. Bought all BSD assets from BSDi, Berkeley Software Design, Inc. Sells BSD/OS commercial BSD Unix, and FreeBSD open source BSD Unix; support, services, and hardware for both OSs, funds OS development. Also sells pSOSystem, OSEKWorks, Virtuoso, VxWorks RTOSs. BSDi used FreeBSD to run ftp.freesoftware.com, Earth's busiest FTP server. http://www.windriver.com/products/html/bsd_os.html