PA-RISC Unix History
Overview
Unix was the standard operating system choice for PA-RISC computer and the main target for PA-RISC while developing it. HP 9000 were dedicated Unix servers and then workstations. Most operating systems for PA-RISC were either Unix implementations or variants of it.
HP developed and ported HP-UX, its commercial Unix offering, to PA-RISC very early on. Closely based on BSD Unix, HP-UX later on moved towards System V. Many of the Asian HP PA-RISC OEMs and clones also used HP-UX variants or own Unix implementations.
Another commercial, Unix-like operating system was NeXTSTEP, ported to PA-RISC during the 1990s, in parallel to other developmental ports of various commercial systems.
The plethora of research projects of the 1990s also used Mach microkernel and Unix-like systems, as did the 2000s open source (OSS) projects.
HP-UX
The story of HP-UX Unix began 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 1.0 or 2.0 the first release on PA-RISC in 1986 or 1987.
Many updates soon followed, even though versioning was a bit complicated during that sparsely documented time. In the 1980s, another HP-UX was released with 3.0, followed by HP-UX 7.0 in 1990. The first HP Unix release that supported both 800 Series servers and the new 700 Series workstation was HP-UX 8.0 and then 9.0 from the early 1990s, still strongly BSD-based.
The new HP-UX 10 was released a few years later in 1995, followed in quick sucession by 10.20 and 10.30. Due to feared Y2K issues in earlier versions, HP made HP-UX 10.20 available free of charge for HP 9000 owners for a while. A server-only 10.30 released followed in 1997, as were many Additional Core Enhancements (ACEs), that added workstation hardware support to HP-UX 10.20.
The modernized HP-UX 11.0 was released soon after, starting in 1997, with a true 64-bit kernel
with full 64-bit support for 64-bit computers but still support for many 32-bit PA-RISC systems.
There was supposedly scant support for workstations in the original 11.00 release that was developed by the HP Server division – to be added later with the EP and ACE in 1998 and 1999.
The focus of HP-UX shifted with 11i to the newer lettered
(A-Class, B-Class) and rp/rx 64-bit and Itanium servers.
HP started developing the HP-UX kernel to support PA-RISC and Itanium already beginning in 1997, and apparently together with NEC and Hitachi, old PA-RISC co-conspirators.
HP-UX 11i v2 from 2003 then integrated PA-RISC and Itanium into a single operating system stream while HP-UX was focused more and more on specialized server roles – and stopped supporting most older
PA-RISC workstations and 32-bit servers too.
NeXTSTEP
NeXTSTEP on PA-RISC was a commercial Mach-based Unix
operating system from the 1990s with an Unix userland and an extremely modern GUI.
It was ported to PA-RISC in 1994 with version 3.3 developed specifically for the HP 9000 712 pizzabox workstation.
Originally introduced in 1989, NeXTSTEP supported black
(NeXT) and white
(Intel) hardware, with support for RISC platforms including Sun SPARC and HP PA-RISC added in 3.3.
Support for PA-RISC in NeXTSTEP was only brief and limited to a select set of 32-bit HP 9000 workstations.
NeXTSTEP itself, while revolutionary in aspects, did not have long commercial success. However some of its ideas and technologies lived on in Mac OS, after much M&A in the tech sector. NeXTSTEP on HP 9000 712 workstations was a rather unique and modern operating system experience for the 90s.
Mainframe
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.
Several third-party operating systems for PA-RISC mainframes were developed by companies for their own computers. This includes Convex SPP/UX, a heavily modified Mach-based operating system familiar to HP-UX but a completely different design for the Convex/HP Exemplar SPP line of mainframes. The fault-tolerant Continuum servers from Stratus were also shipped with either Stratus FTX, a System V Unix, or Stratos VOS, a transaction-processing oriented system.
PRO and East Asia
In the mid-1990s, as part of the Precision RISC Organisation, HP’s PA-RISC consortium, some Asian third-party PA-RISC OEMs started selling their own PA-RISC computers. These either made use of licensed HP-UX versions or their own custom developed operating systems – like Hitachi with HI-UX/WE2 and HI-UX/MPP or Samsung with SS-UX (?).
Other
Besides the well known commercial PA-RISC operating systems and research projects, some interesting operating systems were ported to PA-RISC. Forgotten since, Windows NT and NetWare were ported to PA-RISC in the 1990s as development projects. HP-UX was ported to x86 as a development project to hedge their bets – with mixed results.
Another PA-RISC operating system by HP was HP-RT, a real-time operating system geared towards instrumentation use cases on HP 9000 740 series VME workstations that had a short-ish lifespan between 1993 and 1997, when customers have migrated to new solutions and platforms more rapidly than anticipated.