PA-RISC information - since 1999

About OpenPA

OpenPA is an information resource for PA-RISC computers, technology and operating systems; a registered serial publication with ISSN 1866-2757. First published in 1999, OpenPA has been edited and updated regularly for more than 25 years as an independent, non-commercial publication.

PA-RISC is a RISC computer architecture designed by Hewlett-Packard in the 1980s, used in HP 9000 and Visualize workstations and servers until the 2000s. Some older predecessors of PA-RISC from the 1980s and successors based on HP/Intel Itanium are also covered.

OpenPA is based on public information from sources such as HP guides and handbooks as well as articles, journals and conferences. Availability of information is rather dim these days as documents keep disappearing.

Paul Weissmann is the editor of OpenPA and also publishes OpenKRITIS, a platform for critical infrastructures. He can be reached via email.

An OpenPA Book Edition of the complete project is available.

How come? was founded in December 1999 at a time when Google just started and Wikipedia did not exist yet. The idea was a central independent resource for information on PA-RISC Unix computers, which were widely available in the second-hand market of the late 1990s, early 2000s. OpenPA and contributions peaked in those early years with a lively community around PA-RISC and open source systems.


This site was started in 1999 when second-hand PA-RISC systems became affordable for hobbyists after being phased out of the industry for modern COTS Windows NT and Linux servers. Not much PA-RISC information was readily available on the web then, when other Unix and RISC platforms such as Sun were documented well.

A 715/100 from a local newspaper ad started the interest and slowly led to an archive of PA-RISC documentation from the 1990s. Edited into a simple web site with frames, it was published with hosting provided by Bill Bradford of SunHELP. The late Mickey appeared soon after, with lots of PA-RISC wisdom.

After two years in 2001, the site was renamed and moved to a Digital DECstation 5000 on 1Mb dialup. Increasing support from HP for the PA-RISC Linux project made a lot of official PA-RISC documentation available. Open source operating systems made significant progress, including OpenBSD and Linux. Most HP 9000/700 and many lettered workstations were documented on OpenPA during that time, as were most PA-RISC processors, chipsets and operating systems.


Updates became less frequent after 2005 with minor additions such as the PA-8800 and PA-8900 processors, PA-RISC architecture and operating systems. An OpenPA print edition was finally released with several hundred pages PA-RISC content.

OpenPA in 2006

A burst of activity in 2008 resulted in much new content like 64-bit PA-RISC workstations and rp Series, some mainframes such as Convex SPP, V-Class and some early HP Itanium. Information on the fringes of PA-RISC was added, including third-party processors and OEM systems from Japan and early-1980s PA-RISC computers.


Update frequency and additions stalled considerably after 2008 with mostly low-intensity maintenance and reshuffling of content for more than a decade. The overall Internet and PA-RISC information changed a lot during that time.

OpenPA in 2012

Much HP documentation disappeared during the 2010s, so many links to original sources and references had to be removed. Interest in and support for PA-RISC in open-source systems dwindled as well.

Major housecleaning was done several times from 2016 on, checking links, content and rewriting much original language. Some new additions included a PA-RISC timeline and original equipment prices, a new OpenPA print edition and some restructured sections plus various cleanups in the backend.


OpenPA was refreshed again in the 2020s. Some longer new articles were written after the 20-year anniversary and an effort was made to find new sources to properly document PA-RISC history.

OpenPA in 2021

Some new activities were started plus content was made more readable, sources consolidated and some rather unknown aspects of PA-RISC documented, like PRO, the 1980s, HP-UX and weird operating systems, Apollo and PRISM.

Many OpenPA articles were updated, bad ideas from previous years (decades) reversed and some severely outdated text rewritten with new language. There is still some old, original content scattered throughout OpenPA and many ideas still to be implemented.

The yearbook

Year Changes Content Backend
1999 Started PA-RISC overview from the 90s Frames, dark-mode
2000 7 HP 9000 700s, operating systems Hosted at sunhelp
2001 7 32-bit processors, hardware, more systems mickey@ appeared
2002 21 BSD, A/B/C/J lettered-systems, some 64-bit, X-Terms Renamed, own server
2003 30 Complete 64-bit, four-digit systems, 3rd-party, more OS
2004 14 Benchmarks, FOCUS, graphics, SCSI, architecture Complete revamp, CSS
2005 3 Small updates
2006 4 Final PA-RISCs - Mako, C8000 OpenPA book
2007 3 History, small updates Limited paperback
2008 18 Mainframe/Cell, Itanium, 1980s PA-RISC, others
2009 3 CPU and I/O architecture, much cleanup 10y anniversary
2010 2 T-Class, chipsets
2012 1 OpenPA book update
2014 1 Cleanup and housekeeping
2015 2 Handle disappearing sources and documents
2016 6 Restructure chipset content, timeline, cleanup
2018 3 PA-RISC story, OS updates, disappearing sources Cloud move
2019 20y anniversary
2020 3 Agilent PA-RISC, many systems updates
2021 2 Content mopup, OS history Backend mopup
2022 3 Research OS reorganization, Apollo/PRISM, mopup OpenPA book update
2023 5 PA-RISC history, 1980s, PRO in Japan, OpenPA and Internet
2024 5 Oddball OSs, HP-RT, HP-UX versions, Systems cleanup Frontend mopup

↑ up


Paul Weissmann has been maintainer and author of OpenPA since 1999. Many people helped OpenPA with contributions and support over the years:

Thank you all!

↑ up


The copyright of belongs to Paul Weissmann, Berlin, Bonn, Palo Alto, San Francisco, unless otherwise noted. This site © 1999-2024 Paul Weissmann. No parts of this site may be reproduced or copied without prior written permission. Commercial use of the content is prohibited.

This site does not represent the Hewlett Packard company in any way. This site is not affiliated with Hewlett Packard in any way. It is provided as an informational resource only, for owners and users of PA-RISC computer systems and software and compatible systems. See also Legal Notes.

↑ up