Tru64 is Compaq's name for Digital UNIX, which is the 64-bit UNIX for the Alpha AXP platform. Tru64 is a descendant of OSF/1.
It is unique among common commercial UNIX OS's in that it is built on the Mach kernel often associated with NeXT. It is sometimes criticized for POSIX compatibility holes.
wikipedia.org dumped 2003-03-17 with terodump