μnOS

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UNOS
Company / developer Charles River Data Systems
Written in C
OS family Unix-like
Working state Historic
Latest release 9.3.3+ / July 15, 1997; 16 years ago (1997-07-15)
Marketing target Real-time data acquiring and processing
Supported platforms Motorola 68k, Intel_80486
Kernel type Monolithic

UNOS was the first 32bit Unix-like real-time operating system with real-time extensions. It was developed by Jeffery Goldberg, PhD. who left Bell Labs after using UNIX and became VP of engineering for (now defunct) Charles River Data Systems (CRDS). UNOS was written to capitalize on the first 32 bit microprocessor, the Motorola 68k CPUs. CRDS sold a UNOS based 68K system, and sold porting services and licenses to other manufacturers who had embedded cpu's.

History [1][edit]

Jeff Goldberg created an experimental OS using only Eventcounts for synchronization, that allowed a preemptive kernel, running on a PDP-11 system from Charles River Data Systems (CRDS). CRDS president Rick Shapiro hired Jeff to build full Unix-like OS, UNOS, first marketed on then-new 68000 systems in 1981. CRDS enjoyed a long profitable run selling 68K family systems with Unos before eventually dwindling away. Their primary market was OEMs embedding the CRDS unit within a larger pile of hardware, often requiring better real-time response than Unix could deliver.

UNOS has a cleaner kernel interface than UNIX in 1981. There was e.g. a system call to obtain ps information instead of reading /dev/kmen.

UNOS required memory protection, with the 68000 using an MMU developed by CRDS; and only used Motorola MMUs after UNOS 7 on the 68020 (CRDS System CP20) (using the PMMU (MC68851 PMMU)).

UNOS was written in C and assembler; and supported FORTRAN, COBOL, Pascal, and Basic.

Limitations[edit]

UNOS from CRDS never supported paged VM and multiprocessor support had not been built in from the start, so the kernel remained mostly single-threaded on the few multiprocessor systems built. A UNOS variant enhanced by H. Berthold AG under the name vBertOS added demanded page loading and paged processes in 1984, but was given up in favor of SunOS because of the missing GUI and the missing networking code in Spring 1985, when Berthold imported the first Sun to Europe.

References[edit]