OSF/1 on PA-RISC
Overview
OSF/1 was the third flavor of the Unix operating system after System V and BSD. It was developed by a consortium of DEC, IBM and HP under the auspices of OSF, the Open Software Foundation. OSF/1 Unix used 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 university groups.
HP used PA-RISC computers early for in-house operating system research including early Mach research and a HP OSF/1 port of Mach 2.0 to PA-RISC. Both saw limited distribution and use. In the 1990s OSF, the Open Group alliance ported OSF/1 Unix to PA-RISC (MK-PA) and used parts of this for the later Mach MkLinux port.
HP OSF/1
Around 1990, an internal HP project ported early 1.0 OSF/1 to PA-RISC, the alternative Unix operating system from an alliance of Unix vendors. HP supported the OSF/1 undertaking early on and planned a transition of its Unix offering towards OSF/1 when microkernel Mach operating systems were en vogue in the 1990s.
HP OSF/1 was developed by ex-Apollo staff after Apollo was bought by HP, with Mach 2.0 macrokernel on early HP 9000/700 workstations. The result was a fairly complete OSF/1 operating system with proper hardware support and usable desktop environment with Motif and other OSF/1 applications.
Releases
HP OSF/1 on PA-RISC was never distributed widely and sold commercially only for a short time before being withdrawn.
It was apparently used a lot 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.
Hardware support
HP OSF/1 apparently supported the following HP 9000 PA-RISC workstations:
- HP 9000 720, 730 based on PA-7000 processors
Open Group MK-PA

The OSF Open Group Research Institute ported microkernel OSF/1 to PA-RISC in the mid-1990s as research project. Called MK-PA, the OSF port focused on 32-bit HP 9000/700 workstations and servers. Development was supported by HP OSSD (Open Source Software Development?) in several parts of the kernel and subsystems.
Performance was supposedly similar in HP-UX and MK-PA at the time with some advantages at higher loads for MK-PA OSF:
MK-PA is comparable to that of HP-UX for loads up to 200 simulated users and better for heavy loads.

HP-UX compatibility (HPUX-CM) with HP-UX 9.05 was provided in MK-PA 7.1, compatibility with HP-UX 10 in MK-PA 7.2. For this, Open Group had to make the OSF/1 filesystem HP-UX compatible, extend OSF/1 to support HP-UX system calls and replace the HP-UX kernel with microkernel and HP-UX server. With this, MK7.2 could boot on a HP-UX filesystem with HP-UX binaries like HP-VUE. HP-UX X11 applications like FrameMaker, Mosaic could run on MK-PA.
Releases

OSF MK-PA was never released widely and required obtaining an OSF/1 source license from Open Group, which few institutions had.
- MK6.0-PA in 1994: Performance improvements from MK6, short-circuit RPC, HP-UX compatibility
- MK6.3-PA in 1995: PA-RISC merged in mainline, better performance, robustness and HP-UX compatibility, some RT support, X support
- MK7-PA in 1996: More RT functionality, FDDI and IP multicast, Dynamic Buffer Cache
- MK7.2-PA in 1996: Myrinet, Distributed systems (DIPC, XMM, KKT), real-time functionality, high-precision clock, HP-UX 10.0 compatibility
OSF MK 7.2 ran on both Intel x86 and HP PA-RISC and featured OSF/1 1.3.1 commands and libraries. Parts of MK-PA wound up later in free Mach 4/Lites and MkLinux. There were no known public releases of MK-PA since then.
Hardware support
MK-PA supported PA-RISC 1.1 hardware in HP 9000 workstations with strong HP-UX compatibility. Support for PA-RISC 1.0 was dropped from the original Mach 3/UX code base. MK-PA supported the following HP 9000 computers and hardware:
- HP 9000 710, 720, 730 based on PA-7000 processors
- HP 9000 715, 725, 735, 755 based on PA-7100 processors
- HP 9000 712, 715, 725/100 based on PA-7100LC processors
- HP 9000 J200, J210[XC], based on PA-7200 processors
- Most onboard I/O devices
- Interphase FDDI board, EISA Ethernet boards, HP Labs GSC bus Myrinet board
- Additionally DIPC and CORDS
Usage
OSF MK-PA on PA-RISC was mostly used by research institutions in the mid-1990s and was never distributed widely as commercial operating system.
Research usage included defense-related ARPA projects, where the US Navy (NSWC) used OSF MK7.2 for real-time analysis and display of radar tracking data,
seemingly with TAC-4 support.
PA-RISC computers with MK7.2-PA ran Radar Track Data Servers
to which Pentium and SPARC systems were connected via Myrinet, processing up to 4800 radar tracks/second.
Documentation
- MK-PA: An HP-UX compatible microkernel based Operating System, The Open Group (1998) archive.org
- An HP-UX compatible microkernel based Operating System, OSF RI Grenoble (1997) archive.org
- MK-PA Project Update, James Loveluck (1996: The Open Group) archive.org
- OSF MK 7.2, OSF RI (1997: archive.org, accessed February 2018)
- MK6-PA Performance Results, Open Group RI (1998) archive.org
- HPUX-CM: an HP-UX Compatibility Module for the HP-PA OSF/1 Server, OSF RI (1997) archive.org
- HEWLETT-PACKARD PUTS OSF/1 ON HOLD AS IT MERGES DOMAIN WITH HP-UX, Computer Business Review, March 22, 1992