In 1988, IBM, DEC, HP, and others formed the Open Software Foundation to develop a version of Unix to compete with AT&T and Sun Microsystems. This Unix version, OSF/1 (named after the Open Software Foundation), was soon refined and became known as Digital Unix. OSF/1 is probably best known as the root of the third major branch of the Unix family tree, after System V and BSD.
In 1994, the Open Software Foundation ceased funding of research and development of what had become Digital Unix. The descendant of OSF/1, Tru64, now belongs to Hewlett-Packard's collection of intellectual property and isn't used much anymore.