|Developer||Open Software Foundation|
|Initial release||January 1992|
|Platforms||MIPS, DEC Alpha, PA-RISC|
OSF/1 was a variant of the Unix operating system developed by the Open Software Foundation during the late 1980s and early 1990s. OSF/1 was one of the first operating systems to use the Mach kernel developed at Carnegie Mellon University, and is probably best known as the native Unix operating system for DEC Alpha architecture systems.
In 1994, after AT&T had sold UNIX System V to Novell and the rival Unix International consortium had disbanded, the Open Software Foundation ceased funding of research and development of OSF/1. The Tru64 UNIX variant of OSF/1 was supported by HP until 2012.
In 1988, during the so-called "Unix wars", Digital Equipment Corporation (DEC) joined with IBM, Hewlett-Packard, and others to form the Open Software Foundation (OSF) to develop a version of Unix. Dubbed OSF/1, the aim was to compete with System V Release 4 from AT&T Corporation and Sun Microsystems, and it has been argued that a primary goal was for the operating system to be free of AT&T intellectual property. The fact that OSF/1 was one of the first operating systems to use the Mach kernel is cited as support of this assertion. Digital also strongly promoted OSF/1 for real-time applications, and with traditional UNIX implementations at the time providing poor real-time support at best, the real-time and multi-threading support was heavily dependent on the Mach kernel. It also incorporated a large part of the BSD kernel (based on the 4.3-Reno release) to provide UNIX API. Back at the time of its proliferation, OSF/1 was the third major flavor of UNIX together with System V and BSD.
DEC's first release of OSF/1 (OSF/1 Release 1.0) in January 1992 was for their line of MIPS-based DECstation workstations, however this was never a fully supported product. DEC ported OSF/1 to their new Alpha AXP platform as DEC OSF/1 AXP Release 1.2, released in March 1993. OSF/1 AXP was a full 64-bit operating system. After OSF/1 AXP V2.0 onwards, UNIX System V compatibility was also integrated into the system. Later releases were renamed Digital UNIX, and later, Tru64 UNIX.
HP also released a port of OSF/1 to the early HP 9000/700 workstations based on the PA-RISC 1.1 architecture. This was withdrawn soon afterwards due to lack of software and hardware support compared to competing operating systems, namely HP-UX.
The Open Software Foundation[better source needed] created OSFMK which was a commercial version of the Mach kernel for use in OSF/1, it contains applicable code from the University Of Utah Mach 4 kernel (such as the "Shuttles" modification used to speed up message passing.) and applicable code from the many Mach 3.0 variants that sprouted off from the original Carnegie Mellon University Mach 3.0 kernel,  it also consists of improvements made by the OSF such as built in collocation capability, realtime improvements, and rewriting of the IPC RPC component for better speed use among other things.
OSF/1 AD (Advanced Development) was a distributed version of OSF/1 developed for massively parallel supercomputers by Locus Computing Corporation. Variants of OSF/1 AD were used on several such systems, including the Intel Paragon XP/S and ASCI Red, Convex Exemplar SPP-1200 (as SPP-UX) and the Hitachi SR2201 (as HI-UX MPP).
- Salus, Peter H. (1994). A Quarter Century of UNIX. Reading, Mass: Addison-Wesley Pub. Co. p. 217. ISBN 0-201-54777-5.
- Ellen Minter (1992-01-28). "Press Release — OSF/1". Newsgroup: bit.listserv.esl-l. Usenet: 9201282310.AA15415@enet-gw.pa.dec.com. Retrieved 2007-08-21.
- "PA-RISC R&D Operating Systems". OpenPA.net. Retrieved 18 August 2011.
- Corcoran, Cate (4 November 1991). "Apple reveals plans for updated A/UX, PowerOpen Unix development alliance". InfoWorld. pp. 1, 115.
- "IBM announces AIX/ESA mainframe version of Unix". 1992-04-01. Archived from the original on 2006-02-24. Retrieved 2008-03-28.
- The Open Group
- Jim Magee. WWDC 2000 Session 106 - Mac OS X: Kernel. 12 minutes in.
- Douglas M. Wells. "A Trusted, Scalable, Real-Time Operating System Environment" (PDF).
- Zajcew, Roman; et al. (1993). An OSF/1 UNIX for Massively Parallel Multicomputers (PostScript). USENIX Winter 1993 Technical Conference.[permanent dead link]