PA-RISC information - since 1999

PA-RISC Operating Systems History

The history of PA-RISC operating systems started in parallel to the design and development of PA-RISC and HP 9000 computers. Many Unix and research operating systems were made available in the late-1980s, first the early commercial HP-UX PA-RISC releases, followed by a plethora of research and development projects centered around the Mach microkernel and BSD Unix versions.


HP-UX: The story of HP-UX Unix started before PA-RISC, with versions for the early HP 9000 lineup — the HP FOCUS systems. From the late 1980s on, HP-UX was available on the first PA-RISC server computers (800s), with HP-UX 7.0 released in 1989. Updated and enhanced version soon followed, with the BSD-influenced HP-UX 8.0 and 9.0 from the early 1990s supporting most early HP 9000 700s and 800s.

The new HP-UX 10 was released a few years later, followed in quick sucession by 10.20 and 10.30. Due to feared Y2K issues in earlier versions the, popular HP-UX 10.20 was made available free of charge for HP 9000 owners for a while. The modernized HP-UX 11 was released from the mid-1990s on, with a true 64-bit kernel that still supported many 32-bit PA-RISC systems and hardware. The focus of HP-UX shifted soon to the newer lettered (A-Class, B-Class, ...) and rp/rx 64-bit and Itanium servers in the 11i HP-UX versions during the early 2000s. HP-UX 11i v2 integrated PA-RISC and Itanium into a single operating system stream while HP-UX was relegated more and more to specialized server roles.

NeXTSTEP: NeXTSTEP on PA-RISC was a commercial Mach-based operating system from the 1990s with an Unix userland and an extremely modern GUI, ported by NeXT Inc. to PA-RISC in 1994. Support for some 32-bit PA-RISC machines was available in Version 3.3, which was designed for the HP 9000 712 workstation. Both NeXTSTEP and its support for PA-RISC were wound down soon thereafter — with parts of NeXTSTEP ending up in the 2000s reincarnation of Mac OS.

Other operating systems: There were a few other notable operating systems that ran on PA-RISC. HP’s own MPE business mainframe operating system was ported from the HP 3000 CISC platform to PA-RISC with MPE/XL and MPE/iX, with several releases from 1988 to 2002. Another PA-RISC operating system by HP was HP-RT, a real-time operating system geared towards the HP 9000 740 series VME board workstations.

Several third-party operating systems for PA-RISC were developed by several companies for their own line of computers. This includes Convex SPP/UX, a heavily modified Mach-based operating system, which looks familiar to HP-UX but is a completely different design, for the Convex/HP Exemplar SPP1000, 1200 and 1600 line of mainframes. The fault-tolerant Continuum servers from Stratus were shipped with either Stratus FTX, a System V Unix, or Stratos VOS, a transaction-processing oriented system.

Development: There were apparently development efforts in the mid-1990s to port Microsoft Windows NT to PA-RISC. Several magazine articles (HP edges towards NT support in Computerworld 12/13/93) and USEnet posts around 1993 mentioned as much that HP was pursuing a PA-RISC port to NT and even conducted a back-room presention of a PA-7100LC workstation running Windows NT. Around the same time, a two-year effort to port the NetWare operating system to PA-RISC was mentioned.

Apparently there was a prototype port of HP-UX to x86 hardware, at a time when the future of HP-UX and the sole surving hardware platform Itanium came in doubt during the early 2010s — PA-RISC was long gone then.

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Open source

Linux: A native Linux port to PA-RISC was started in 1998 and gained momentum when HP started helping with equipment and documentation in 1999. The main Linux port quickly superseded the earlier Mach-based MkLinux. Because of HP’s assistance, the machines targeted at that time were newer than what other ports supported, like the A180, B180 and 64-bit PA 2.0 systems.

PA-RISC support was included in the mainstream kernel, and shipped with Debian and Gentoo distributions as official ports. During the 2010s however, support declined and development was scaled back, resulting in the eventual removal of PA-RISC from official distributions. PA-RISC Linux still has the broadest support for systems and hardware from the current open source efforts.

BSD: Work on an OpenBSD port to PA-RISC on HP 9000/700 systems was started by Michael Shalayeff around 1999. His porting efforts were based a lot on source code and information from the previous PA-RISC research projects Lites/HPPA and MkLinux. The first complete OpenBSD/hppa release was version 3.5, with PA-RISC having been supported since on most 32-bit workstation, some 64-bit workstations and some servers. An OpenBSD/hppa64 port to support PA-RISC 2.0 computers running natively in 64-bit mode was started in 2007, but never took off.

NetBSD/hppa is a free, open source Unix-like operating system, and supports PA-RISC computers since around 2005, called NetBSD/hp700 until the 7.0 release, as a Tier II port. The port focuses on 32-bit PA-RISC 1.1 computers and 64-bit PA-RISC 2.0 systems in 32-bit. The current effort is largely based on Michael Shalayeff’s work on the OpenBSD/hppa kernel from 2004 to 2005 and updated OpenBSD code later on.

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R&D: As soon as PA-RISC was released in the late 1980s, academic and industrial research projects started operating systems ports to PA-RISC. The premier among them was HPBSD from the University of Utah which was a port of 4.3BSD and later 4.4BSD to early 800s servers and specially the early 700s workstations. HPBSD contained commercial AT&T and HP code, and was never freely available.

Several ports of the Mach microkernel were undertaken during the early 1990s, with HP Tut using Mach 2.0 and the University of Utah trying Mach 3 and Mach 4. Porting efforts for OSF/1, the alliance Unix operating system from DEC, IBM, HP and others to compete with AT&T and Sun’s System V Unix, started around 1990. HP itself ported OSF/1 to PA-RISC, which was never widely available commercially. This port was superseded in the mid-1990s by the OSF RI Open Group Research Institute with several releases of MK-PA. All of the Mach ports were never really used widely as production systems, but formed the basis for other research projects and later the BSD and Linux ports.

Early Linux support on PA-RISC built upon the MkLinux research project from the mid-1990s by the Open Group/OSF, that ported a Linux kernel onto a Mach microkernel, which in turn built on the previous MK-PA OSF/1 port to PA-RISC.

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The approximate timeline of operating system development is as follows.

PA-RISC operating systems timeline, development, 📘 release.
Year HP-UX Linux OpenBSD NetBSD HP-BSD Mach 3 Mach 4 OSF/1 MkLinux NeXTSTEP
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Further reading