PA-RISC information - since 1999

PA-RISC Operating Systems

Many operating systems have been available over the years for PA-RISC computers. Most of them are either commercial Unix or derivates and open source projects with different designs ported to and developed specifically for PA-RISC. An article details the history of PA-RISC operating systems chronologically and more in-depth.


The main operating system for PA-RISC was HP-UX, the native Unix for HP 9000 computers sold by HP, in parallel to more niche products for transactions and real-time markets – MPE/iX and HP-RT. Next to these, a slew of other, specialized systems were commercially ported to PA-RISC.

Open source

Several open source operating systems are available for PA-RISC, having been developed in the early 2000s with proper, mostly stable hardware and software support since then.

Research and Development

PA-RISC was used for many research projects in the era of the late-80s to the mid-90s, when microkernel research was popular. Many projects were based on Mach or leaned on it, at various places lile HP, Open Group (OSF) and the University of Utah:

Of these MkLinux and Mach 4/Lites were publically available, the others required licenses for commercial or NDA source code they contained. The later Linux and BSD ports made heavy use of their codebase and developments.

Oddballs: A few corporate development projects were pursued for commercial operating systems over the years. Reportedly HP developed a prototype port of Microsoft Windows NT to PA-RISC in 1993 resulting in NT running on a 712 workstation. In the same timeframe, sources mention a two-year effort to port the Novell NetWare operating system to PA-RISC, which HP quit in 1994. And an era later, there was apparently a prototype port of HP-UX to x86 in the 2010s (!) when the future of HP-UX and Itanium was in doubt after PA-RISC was gone.

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Support overview

Approximate support matrix for various operating systems on the HP 9000 PA-RISC series’.

PA-RISC OS support, 📘 - full support, - partial support
OS 700s 740s 800s A B C D E FGHI J K L N R rp rx SD T V
HP-UX 9 📘 📘 📘 📘
HP-UX 10.20 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘
HP-UX 11.00 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘
HP-UX 11i v1 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘
HP-UX 11i v2 📘 📘 📘 📘 📘
HP-UX 11i v3 📘 📘 📘 📘
Linux 📘 📘 📘 📘 📘 📘 📘 📘 📘 📘
OpenBSD 📘 📘 📘
NetBSD 📘 📘 📘
Mach 3
Mach 4

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