It is unusual among commercial UNIX implementations, as it is built on top of the Mach kernel developed at Carnegie Mellon University.

(Other UNIX and UNIX-like implementations built on top of the Mach kernel are GNU Hurd, NeXTSTEP, MkLinux, and Darwin.)

In 1988, Digital Equipment Corporation (DEC) joined with IBM, Hewlett-Packard, and others to form the Open Software Foundation (OSF).

[5] A Chinese version of Tru64 UNIX named COSIX was jointly developed by Compaq and China National Computer Software & Technology Service Corporation (CS&S).

Each member had one or zero votes, which, combined with a possible quorum disk, implemented a cluster formation algorithm similar to that found in OpenVMS.

With their purchase of Compaq in 2002, HP announced their intention to migrate many of Tru64 UNIX's more innovative features (including its AdvFS, TruCluster, and LSM) to HP-UX.