Tru64 UNIX is a 64-bit UNIX operating system for the Alpha instruction set architecture (ISA), currently owned by Hewlett-Packard (HP). Previously, Tru64 UNIX was a product of Compaq, and before that, Digital Equipment Corporation (DEC), where it was known as Digital UNIX (formerly DEC OSF/1 AXP).As its original name suggests, Tru64 UNIX is based on the OSF/1 operating system.