MIPS RISC/os
| Developer | MIPS Computer Systems, Inc. |
|---|---|
| OS family | Unix-like |
| Platforms | MIPS architecture |
RISC/os was a UNIX operating system distributed by MIPS Computer Systems, Inc. during the 1980s and 1990s for use with their computer workstations and servers, such as the M/120 server or MIPS Magnum workstation. It was also sometimes referred to as UMIPS.
RISC/os was based largely on UNIX System V with additions from 4.3BSD UNIX, ported to the MIPS architecture. The RISC/os user environment could be configured for compatibility with either System V Release 3, 4.3BSD, or (in later versions) System V Release 4. MIPS OS was one of the first 32-bit operating systems for RISC-based workstation-class computers. It was also on of the first 64-bit Unix releases for RISC based microprocessors, with the first 64-bit versions appearing in 1990. MIPS OS supported full 32-bit and 64-bit applications simultaneously using the underlying hardware architecture supporting the MIPS-IV instruction set.
The MIPS OS, originally developed by MIPS Computer Systems Inc. in 1985, was originally used on the MIPS Computer Systems' own line of workstations. It was a dual-universe operating system, meaning that it had separate, switchable runtime environments to closely model both the BSD and System V flavors of Unix. It was arguably a successful concept, but it never really gained widespread acceptance, and the MIPS OS itself never ran on any platforms other than MIPS' own workstations. In spite of the failure of MIPS' to sell workstations in quantity, MIPS OS development continued steadily with product releases and upgrades including adding support for System V Release 4, R6000 processor support and later SMP support on the R4400 and R6000 processors.
During the early 1990s, several vendors including DEC, Silicon Graphics, and Ardent licensed portions of the software MIPS had written for the MIPS OS for their own Unix variants. MIPS' influence was most visible as the C compiler and development tools shared by virtually all commercial Unixes for the MIPS processor, the low memory operating system code, and the ROM code for MIPS processors.
Because of its early UNIX heritage, RISC/os was limited in comparison to modern UNIX variants — for example, even the last releases of RISC/os did not support shared libraries[citation needed].
In July 1992, Silicon Graphics purchased MIPS Computer Systems for $220M. With Ardent/Stardent/Kubota disappearing during the 1990s and DEC moving to OSF/1 and then Tru64 before being bought out by Compaq (later Hewlett-Packard), pieces of the MIPS OS legacy were incorporated into IRIX, which runs on the MIPS based SGI workstations.
