HP-UX (Hewlett-Packard Unix) is Hewlett-Packard's proprietary implementation of the Unix operating system.
Recent versions support the HP 9000 series of computer systems, based on the PA-RISC processor architecture, and HP Integrity systems, based on Intel's Itanium architecture.
Official web site: http://www.hp.com/go/hpux/
Software ports: http://hpux.connect.org.uk/
HP-UX man pages: http://www.polarhome.com/service/man/?of=HP-UX