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| RISC/os | |
|---|---|
| Developer | MIPS Computer Systems, Inc. |
| OS family | Unix |
| Working state | Discontinued |
| Supported platforms | MIPS architecture |
RISC/os is a discontinuedUNIXoperating system developed byMIPS Computer Systems, Inc. from 1985 to 1992, for their computerworkstations andservers, including such models as the MIPS M/120 server andMIPS Magnum workstation.[1] It was also known asUMIPS orMIPS OS.[2]
RISC/os was mainly based onUNIX System V with additions from4.3BSD UNIX, ported to theMIPS architecture. It was a "dual-universe" operating system, meaning it had separate, switchable runtime environments that were compatible with eitherSystem V Release 3 or4.3BSD.[2] MIPS OS was one of the first32-bit operating systems forRISC-based workstation-class computers. It was also one of the first64-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. Later releases added support forSystem V Release 4 compatibility,[2]R6000 processor support and latersymmetric multiprocessing support on theR4400 and R6000 processors.
During the early 1990s, several vendors includingDEC,Silicon Graphics, andArdent licensed portions of the software MIPS had written for the RISC/os for their own Unix variants.[citation needed]Evans & Sutherland licensed RISC/os directly for its ESV series workstations. MIPS' influence was most visible as theC 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.[citation needed]
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 supportshared libraries.[citation needed]
In July 1992, Silicon Graphics purchased MIPS Computer Systems for $220M. Support for RISC/os was subsequently phased out.[2]
