PRIMOS

PRIMOS is a discontinued operating system Prime Computer built in the early 1970s for its own line of minicomputers, becoming, by the mid-1980s, a serious rival to other mainline minicomputer operating systems, and shipping its last official release, version 24.0.0.R52, on July 3, 1997. It ran only on Prime Computer hardware, including the P400 and 9950 series, used a monolithic kernel, and was unusually written in high level languages rather than assembly, starting in FORTRAN IV and later adding PL/P, Modula-2 and SPL, which let customers modify it for their own needs. It offered virtual memory, disk mirroring for fault tolerance and a networking system called PRIMENET for transparent file access across machines. Prime Computer left the market as personal computers rose and the minicomputer industry declined in the early 1990s, and both the Prime and PRIMOS trademarks had expired by 2010. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/