Chorus on PA-RISC
Overview
Chorus was an early micro-kernel operating system, started as research project by the French research institute INRIA. It was commercialized in the 1980s by a spinoff, Chorus Systems. Chorus was ported to a few RISC architectures and used parts of System V Unix userland. Apparently, it was used by Unisys for a while in the 1990s, before Chorus was bought by Sun.
A development port to PA-RISC was done between 1990 and 1991 at the Oregon Graduate Institute (OGI) for the HP 9000 834 system, based on Chorus v3.3/MiX v3.2. The port was supported by HP and Chorus and done by two PhD students with some help.
For the PA-RISC port at OGI, none of the team members had performed an operating system port before, neither did they have any experience working with the PA-RISC or Chorus.
Later on, an attempt to port Chorus/MiX V.3.2 (v3.4 nucleus) to an HP 9000 720 workstation was made at OGI, the 720 being a popular target for OS/Unix porting efforts at that time.
Hardware support
Hardware support and functionality of Chorus on PA-RISC was limited, with apparently no network interfaces or disk devices supported and console I/O depending on PDC and IODC routines. Code from various earlier projects was used, including from HP-UX 2.0 and HP Tut, Mach 2.0.
Releases
Chorus on PA-RISC was never released publically, since it used HP source code from HP Tut (Mach) and HP-UX and the USL.
The following releases
were available as source from FTP mirrors.
- CHORUS v3.3: Support for HP 9000 834 (1991)
- Chorus/MiX V.3.2: Support for HP 9000 720 (1994?)
Documentation
- Porting Chorus to the PA-RISC: Project Overview Porting Chorus to the PA-RISC: Project Overview, 1992 Oregon Graduate Institute of Science & Technology (1994, J. Walpole, J. Inouye et al.) pdxscholar
- Porting Chorus to the PA-RISC: Overall Evaluation, 1992 Oregon Graduate Institute of Science & Technology (1994, J. Walpole, J. Inouye et al.) pdxscholar
- comp.os.chorus Frequently Asked Questions (FAQ), 1998, FAQS.org pdxscholar
- Chorus Ports: comp.os.chorus, Jon Inouye Nov 29, 1994, google groups
- PA-Chorus, Oregon Graduate Institute (OGI) (1999 archive) archive.org
- Modularity and Interfaces in Micro-Kernel Design and Implementation: A Case Study of Chorus on the HP PA-RISC, Proceedings of the USENIX Workshop on Micro-Kernels and Other Kernel Architectures 1992