PA-RISC information - since 1999


OSF/1 was the third flavor of Unix besides System V and BSD, developed by a consortium between DEC, IBM and HP under the auspices of the Open Software Foundation, OSF. OSF/1 Unix used the Mach microkernel, developed at Carnegie Mellon University (CMU), in a commercial setting. There were several experimental ports of OSF/1 to PA-RISC – from HP, OSF and probably also university groups.

HP used PA-RISC computers early in their life cycle for in-house operating system research. There is public information on at least HP Tut (early Mach) and the HP OSF/1 port of Mach 2.0 to PA-RISC of the late-1980s, both of which saw limited distribution and use. A while later in the 1990s, the OSF Open Group alliance ported its OSF/1 Unix onto PA-RISC as MK-PA research project, and used parts of that for the later Mach MkLinux port.

There apparently was a separate University of Utah OSF/1 to PA-RISC research project, with a Mach 3.0 (NMK14.4) and OSF/1 1.0.4 server used for threading research.


Around 1990 an internal HP project ported an early 1.0 version of OSF/1 to PA-RISC, being the alternative Unix operating system from an alliance of DEC, IBM, HP and others to compete with AT&T’s and Sun’s System V Unix. HP supported this undertaking early on, and planned subsequent transitions of its Unix offering towards OSF/1, when microkernel Mach operating systems were en vogue.

HP OSF/1 was developed by ex-Apollo staff, after Apollo was bought by HP, and ported an Mach 2.0 macrokernel to the early HP 9000/700 workstations, resulting in a fairly complete OSF/1 operating system, with proper hardware support and a usable desktop environment with Motif and other OSF/1 applications. The port was never distributed widely and sold commercially only for a short time before being withdrawn quickly. It was apparently used widely at the University of Utah, but HP decided against betting on it commercially, [f]inding fault with at least OSF 1.0’s memory management, [HP] has distributed only limited quantities of what it considers a technical release.

OSF/1 apparently supported the following HP 9000 PA-RISC workstations:

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The OSF Open Group Research Institute ported OSF/1 to PA-RISC in the mid-1990s as a research project, focusing on 32-bit HP 9000/700 workstations and servers. Research releases were MK6.0-PA in 1994, MK6.3-PA in July 1995 and MK7-PA and MK7.2-PA in 1996. Porting was supported by HP in some way. MK-PA was never distributed or released widely, but used for research purposes a lot, including for ARPA projects (to include radar tracking). Obtaining MK-PA from OSF RIrequired an OSF/1 source license.

Hardware support focused on PA-RISC 1.1 700s workstations, support for the 800s PA-RISC 1.0 servers was dropped from the original Mach 3/UX code base. MK-PA as research project had as its main objectives to demonstrate: PA-RISC as OSF RI reference platform, performance parity between HP-UX and MK based systems, HP-UX binary compatibility, high-speed networking capability. Performance was similar between HP-UX and MK-PA at that time. HP-UX compatibility was provided for HP-UX 9.05 on the MK-PA 7.1 release; compatibility for HP-UX 10 was apparently achieved with MK-PA 7.2. OSF MK 7.2 ran on both Intel x86 and HP PA-RISC and featured OSF/1 1.3.1 commands and libraries.

The version of Mach 3 used by the OSF porting effort contained several of the Mach 4 enhancements of the University of Utah and probably used parts of the Mach 3/UX PA-RISC codebase. Parts of the MK-PA port itself were then used in turn as the base of the OSF port of Linux onto OSF Mach, MkLinux.

MK-PA supported the following HP 9000 computers and hardware:

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