UNOS is a discontinued

real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix ...

(RTOS); it was the first

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

system with real-time extensions. It was developed by Jeffery Goldberg, MS. who left

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

after using

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

and became VP of engineering for Charles River Data Systems (CRDS), now defunct. UNOS was written to capitalize on the first 32-bit microprocessor, the

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...

68k

central processing unit A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions ...

(CPU). CRDS sold a UNOS based 68K system, and sold porting services and licenses to other manufacturers who had embedded CPUs.

History

Jeff Goldberg created an experimental OS using only eventcounts for synchronization, that allowed a preemptive kernel, for a Charles River Data Systems (CRDS)

PDP-11 The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...

. CRDS hired Goldberg to create UNOS and began selling it in 1981. UNOS was written for the

Motorola 68000 series The Motorola 68000 series (also known as 680x0, m68000, m68k, or 68k) is a family of 32-bit computing, 32-bit complex instruction set computer (CISC) microprocessors. During the 1980s and early 1990s, they were popular in personal computers and ...

processors. While compatible with

Version 7 Unix Version 7 Unix, also called Seventh Edition Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commerc ...

, it is also an RTOS. CRDS supported it on the company's Universe 68 computers, as did

's Versabus systems. CRDS's 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/kmem. 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 MC68851 PMMU). UNOS was written in the programming languages C and

assembly language In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence bet ...

, and supported Fortran,

COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural, and, since 2002, object-oriented language. COBOL is primarily ...

, Pascal, and Business Basic.

Limits

UNOS from CRDS never supported paged virtual memory 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 SunOS is a Unix-branded operating system developed by Sun Microsystems for their workstation and server computer systems from 1982 until the mid-1990s. The ''SunOS'' name is usually only used to refer to versions 1.0 to 4.1.4, which were based ...

because of the missing GUI and the missing networking code in Spring 1985, when Berthold imported the first Sun to Europe.

References

Discontinued operating systems Embedded operating systems Real-time operating systems Unix variants 68k architecture X86 operating systems {{Operating-system-stub