3DA was an alliance formed between The Santa Cruz Operation (SCO) and Hewlett Packard (HP) in September 1995. Its purpose was to unify SCO's OpenServer product, UnixWare

UnixWare

UnixWare is a Unix operating system maintained by The SCO Group . UnixWare is typically deployed as a server rather than desktop. Binary distributions of UnixWare are available for x86 architecture computers. It was originally released by Univel, a jointly owned venture of AT&T's Unix System...

 (newly acquired from Novell

Novell

Novell, Inc. is a multinational software and services company. It is a wholly owned subsidiary of The Attachmate Group. It specializes in network operating systems, such as Novell NetWare; systems management solutions, such as Novell ZENworks; and collaboration solutions, such as Novell Groupwise...

), and HP-UX

HP-UX

HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...

 from HP; the resulting product would then become the de facto Unix standard for both existing x86 systems and the upcoming IA-64 processor architecture from Intel.

In September 1996, SCO announced that they were offering a "code-level preview" of the system, codenamed Gemini.

By 1998 the alliance had ground to a halt, setting the stage for Project Monterey

Project Monterey

Project Monterey was an attempt to build a single Unix operating system that ran across a variety of 32-bit and 64-bit platforms, as well as supporting multi-processing...

.