Chorus Systèmes SA
| Company type | Private |
|---|---|
| Industry | Software, Operating systems |
| Founded | 1986 |
| Founder | Hubert Zimmerman, Michel Gien |
| Defunct | 1997 |
| Fate | Acquired by Sun Microsystems |
| Headquarters | Saint-Quentin-en-Yvelines , France |
Area served | Europe, United States |
Key people | Hubert Zimmerman (President and CEO), Michel Gien (CTO and Director of Research), Will Neuhauser (President of US subsidiary) |
| Products | Chorus distributed microkernel operating system, Chorus/MiX operating system, Chorus/Fusion for SCO Open Systems Software |
Number of employees | 30 (mid-1989) (1989) |
Chorus Systèmes SA was a French software enterprise operating from 1986 until 1997, established to commercialize innovations originating from the Institut national de recherche en informatique et en automatique (INRIA). Its flagship offering was the Chorus distributed microkernel operating system, created at a time when microkernel architecture was considered pivotal for the evolution of operating systems. Prior to its acquisition by Sun Microsystems in 1997, Chorus formed strategic alliances centered on Unix and associated technologies.
Origins
The development of the Chorus distributed operating system started at INRIA in 1979 under the leadership of Hubert Zimmerman, a notable figure in networking who developed the influential OSI reference model. The French CYCLADES project played a substantial role in shaping Chorus by seeking to embed networking principles directly into operating system kernel design, enhancing traditional monolithic kernels with communication and distribution capabilities.
Between 1980 and 1986, multiple iterations of Chorus—ranging from Chorus-v0 to Chorus-v2—were produced at INRIA. Concurrently, Michel Gien directed another INRIA initiative named Sol, which aimed to create a Unix operating system tailored for French minicomputers, employing the Pascal programming language rather than C to leverage contemporary software engineering practices. In 1984, Sol merged with Chorus, prompting Chorus-v2 to adopt interfaces compatible with Unix System V instead of proprietary ones.
Early Development
With microkernel technology promising significant progress in operating systems and distributed computing, Chorus Systèmes SA was founded in 1986 to bring INRIA’s research to market. Co-founded by Zimmerman and Gien, the company transitioned from publicly funded research towards a startup model inspired by innovators like Robert Metcalfe of 3Com. Several engineers from INRIA joined this new venture. Zimmerman took on the role of president and CEO, while Gien served as chief technology officer and director of research.
At a time when French technology startups were uncommon, Chorus Systèmes and ILOG emerged as pioneers. Due to the absence of venture capital in France, funding was primarily sourced from European initiatives and governmental contracts, notably through INRIA and France Telecom. The company operated out of Saint-Quentin-en-Yvelines near Paris and attracted international engineering talent thanks to its founders’ research backgrounds, cutting-edge projects, and appealing location. By mid-1989, the workforce had grown to approximately 30 employees.
During its initial two years, Chorus concentrated solely on refining its core technology, postponing revenue-generating activities such as consulting services. Around 1988, the release of Chorus-v3 introduced enhancements in real-time processing and distributed system functionalities. These improvements drew upon lessons from other microkernel developments, striking a balance between advanced research and practical industrial requirements. Chorus-v3 featured MiX, a Unix variant integrated with the Chorus Nucleus; together they were marketed as the Chorus/MiX™ operating system.
Focus on Unix
Chorus Systèmes sought to influence the future trajectory of Unix technology. Founder Zimmerman argued that existing Unix implementations had reached their limitations and necessitated a novel kernel architecture. The company aimed to broaden Unix’s market presence with an objective to capture a 10% share of this expansion.
Company leaders engaged with both the Open Software Foundation and Unix International, the principal entities involved in the Unix Wars, seeking their endorsement for the Chorus microkernel while aligning with their specifications. Additionally, Chorus pursued collaborations with hardware manufacturers to encourage adoption of its technology.
In early 1990, GEC Plessey Telecommunications selected Chorus for its upcoming System X digital switching platform, representing Chorus’s largest contract at that time. Partnerships also included working with Gipsi SA, an X terminal producer. That year saw Unisys choose Chorus as the foundation for a Unix operating system, while Intel’s Scientific Computers division adopted it for the Intel iPSC supercomputer.
In 1991, the Chorus microkernel was ported to the transputer architecture developed by Inmos, as well as to the ARM3 RISC processor from Acorn Computers, targeting multimedia workstation applications. In 1992, collaboration with Tolerance Computer led to development of the first fault-tolerant Unix designed for microcomputer-class systems. Meanwhile, ICL incorporated the Chorus microkernel into its GOLDRUSH MegaSERVER—a parallel database server supporting up to 64 SPARC processors running a Chorus-based Unix System V Release 4—utilizing Chorus/MiX V.4 specifically.
Business aspects
Within the microkernel domain, the primary competitor to Chorus was the Mach system developed at Carnegie Mellon University. Concurrently, other notable projects included Amoeba from Vrije Universiteit Amsterdam and V at Stanford University. While Chorus and Mach shared numerous architectural principles, they diverged in their approaches to naming conventions, addressing schemes, and protection mechanisms. Chorus distinguished itself by providing enhanced adaptability at the boundary between kernel and user modes. Among these initiatives, Chorus uniquely delivered a market-ready commercial product.
In 1990, Chorus Systèmes expanded its operations by founding a U.S. branch, Chorus Systems Inc., based in Beaverton, Oregon. Starting with a team of seven employees led by president Will Neuhauser, the subsidiary aimed for rapid growth. Despite significant promotional efforts in the United States, initial sales predominantly occurred within Europe. By that year, Chorus Systèmes had achieved annual revenues near $6.5 million and attracted multiple investors. Ownership as of mid-1991 was primarily held by founders and staff at 63%, with Innovacom owning 16%, and smaller shares distributed among Soffinova, Credit Lyonnais, Banexi Ventures, and Banque Hervet.
In 1991, Unix System Laboratories (USL), a division spun off from AT&T, entered into a partnership with Chorus Systèmes to develop support for USL's Unix System V Release 4 on the Chorus/MiX platform. This collaboration aimed to boost scalability for parallel processing and distributed computing environments. USL contributed $1 million in funding to Chorus Systèmes as part of this effort. The initiative was integrated within the larger $14 million Ouverture project, conducted under the auspices of the European Strategic Program on Research in Information Technology (ESPRIT) managed by the European Commission.
The capacity of microkernels to operate multiple operating systems simultaneously attracted interest from Novell, which sought to merge its NetWare networking capabilities with USL’s SVR4-based UnixWare. In 1994, Novell announced its intention to develop "SuperNOS," a microkernel-driven network operating system leveraging USL-Chorus technology designed to challenge Microsoft's Windows NT. Despite considerable engineering resources and industry focus, internal conflicts and architectural disputes hindered progress. Subsequently, in late 1995, Novell divested its Unix business to The Santa Cruz Operation (SCO), effectively ending SuperNOS development.
Since 1992, SCO had been collaborating with Chorus Systèmes to integrate SCO’s OpenServer Unix variant with the Chorus microkernel targeting real-time telecommunications applications. This partnership yielded Chorus/Fusion for SCO Open Systems Software, released in 1994. SCO continued advancing this technology through the mid-1990s by creating a dedicated unit tasked with re-engineering OpenServer atop Chorus for telecom purposes under the SCO Telecommunications OS Platform initiative. In 1996, SCO and Chorus unveiled a strategic technology plan for this product—codenamed MK2—aimed at telephone switching systems and multimedia servers, securing adoption from Siemens Private Communications Systems. Nevertheless, this endeavor was ultimately discontinued before reaching full deployment.
Other projects
Object-oriented operating systems represented a significant research area, with several projects exploring their implementation on microkernel platforms. One such example is GUIDE, developed by the Universities of Grenoble; it implemented an object-oriented OS on Chorus, Mach, and Unix to facilitate comparative analysis among these systems.
Chorus Systèmes also created COOL (Chorus Object-Oriented Layer), introduced in late 1988 through collaboration with INRIA and France Telecom’s SEPT laboratory. COOL was designed to support distributed groupware applications and evolved into a two-tier architecture comprising clusters at the foundational level and objects at the upper layer. This redesign occurred alongside the ISA and Commandos projects within ESPRIT and reached completion by late 1991. The findings from this work were published in Communications of the ACM in 1993.
Additional projects investigated integrating Chorus with Mac OS, drawing inspiration from models like Mach 3.0 running DOS or Mac OS as user-space processes. Building upon previous efforts that ported the Chorus simulator to Apple's A/UX environment, these initiatives progressed toward porting Chorus onto Macintosh IIcx hardware. This enabled Chorus to operate as an application within Mac OS itself, establishing a "cohabitation" framework between the two systems.
Shift in Strategic Direction
Chorus redirected its development efforts toward real-time operating systems tailored for embedded systems. Within the framework of ESPRIT's STREAM initiative, Chorus was architected as a modular system with scalable features, spanning from a compact 10K-byte "nanokernel" providing fundamental executive and memory management functions to a comprehensive distributed operating system capable of supporting Unix.
Subsequently, the company moved away from its Unix focus, aligning with customer demand for the Java platform in real-time device applications. In February 1997, Chorus introduced the Chorus/Jazz product, which facilitated Java applications within distributed, real-time embedded environments. This involved licensing JavaOS from Sun Microsystems and substituting its hardware abstraction layer with the Chorus microkernel. At that stage, Chorus Systèmes marketed three embedded solutions: Chorus/Micro designed for small-scale, hard real-time tasks; Chorus/ClassiX targeting larger systems compliant with RT-POSIX standards; and Chorus/Jazz aimed at Java-based implementations.
By 1997, prominent clients in telecommunications included Alcatel-Alsthom, Lucent Technologies, Matra, and Motorola, with annual revenues reaching $10 million. The company was actively exploring acquisition possibilities. Although SCO had shown prior interest, it considered Chorus’s valuation excessive. Nonetheless, existing relationships with Sun co-founder Bill Joy and ongoing Java collaborations positioned Sun Microsystems as a logical acquirer.
Sun Acquisition and Subsequent Developments
In September 1997, Sun Microsystems purchased Chorus Systèmes SA for roughly $26.5 million, marking a strategic move into the expanding embedded systems sector. The acquisition brought Chorus technology under Sun’s newly established Embedded Systems Software division, rebranding it as ChorusOS. Sun integrated ChorusOS with Sun Solaris to create robust telecommunications solutions emphasizing high availability.
During the early 2000s economic downturn, Sun restructured and ultimately discontinued ChorusOS. Approximately thirty members of the original Chorus team founded Jaluna, focusing on virtualization technologies inspired by microkernel architecture. Jaluna later rebranded as VirtualLogix and was acquired by Red Bend Software in 2010.
Further reading
- Section 18.3.