Tru64 is a Unix variant produced originally by Digital Equipment Corporation for use on the Alpha platform which they also invented. It has several names. Version 1.0 through 3.0 used the moniker “OSF/1” but in the 4.0 versions it was called “Digital Unix” (ironically called that right after Compaq bought DEC). Then in version 5 and after it was called Tru64 to reflect it's 64-bit internals.
Tru64 runs on the DEC ALpha, later taken over by HP/HPE. This processor was discontinued in 2003 after the release of it's final instantiation: the EV7.
We document several standard procedures for Tru64 to help users through these situations.