Elxsi was a minicomputermanufacturing company established in the late 1970s along with a host of other competitors in Silicon Valley, USA. The Elxsi processor was an Emitter Coupled Logic design that featured a 50-nanosecond clock, a 25-nanosecond backpanel bus, IEEE floating-point arithmetic and a 64-bit architecture. It allowed multiple processors to communicate over a common bus called the Gigabus, believed to be the first company to do so. The operating system was a message based operating system called EMBOS. The Elxsi CPU was a microcoded design, allowing custom instructions to be coded into microcode.
History
Elxsi was founded in 1979 by Joe Rizzi and Thampy Thomas. It is believed that Elxsi was the first startup founded by an Indian in Silicon Valley. Much of the architecture of the Elxsi machine was designed by former Stanford University professors Len Shar and Balasubrimanian Kumar. Another key contributor to the design was Harold McFarland, who was also a key designer on the team that created the PDP-11. George Taylor provided a key design for the IEEE floating point unit. Elxsi was bought out by Gene Amdahl with money that was left over from the Trilogy venture. Venture investors in Elxsi included Tata Group and Arthur Rock. In 1989, however, Elxsi left the computer business because of the general shift away from the use of mainframes in the global computer industry and the advent of the personal computer. The Tata Group kept the name Tata Elxsi but it now belongs to the Tata group of companies. The original Elxsi Corporation, however, remained in business as a going concern. In 1989, the company sold its computer maintenance business to National Computer Systems. In 1991, the company entered two entirely different lines of business: restaurants and sewer inspection equipment. ELXSI is still engaged in these businesses, as well as its CUES unit, which makes video pipeline inspection equipment. Before its withdrawal from the computer industry, the large range of hardware expansion gave the machine some success in departmental technical computing environments. The 64-bit registers and ability to do parallel adds within them gave it an unanticipated advantage in COBOL benchmarks, where it outperformed some mainframes. And the extreme independence of the CPUs, coupled with the ability to lock processes into register sets and later, the ability to partition the caches, gave it some success in real time applications.
Hardware
The machine was a mini-supercomputer: a category of computers that was larger than a VAX 11/780 and smaller than a mainframe. This market segment disappeared as high-end microprocessor-based systems became more powerful. The architecture was unusual, especially for its day. The system bus connected as many as 12 CPUs and I/O processors. Each CPU was built from three large boards of ECL gate arrays. Key elements of its instruction set architecture were:
Small set of instruction lengths, length determinable from first few nibbles of instruction
No hardware cache coherence among processors
Microcoded message system to communicate among software processes and with I/O controllers and CPU microcode
No supervisor mode—equivalent restrictions applied by controlling which processes held special message system communication links and which virtual address space had the memory management tables mapped into it
Multiple hardware CPU interrupts that supported real-time computing applications
Two generations of CPU were sold and a third developed but never sold. All plugged into the same backplane and could be intermixed in a single system.
Software
The EMBOS OS was written entirely from scratch in a slightly extended Pascal. It was a multi-server architecture. The UI was Unix-like, especially at the shell level, with similar concepts but different commands, syntax, etc.. Later, a Unix kernel was hosted on top of the lower-level servers so that EMBOS and Unix processes and users could co-exist. VMS compatibility software running on top of EMBOS was also added to ease porting of VAX applications.
Famous employees
Although Elxsi was not a financial success, many of its employees did go on to fame and fortune.
Joe Rizzi co-founded Liquid Robotics, now a subsidiary of the Boeing Company; Rizzi and William Stutz are among the cofounders of the related, oceanographic Jupiter Research Foundation, a 501 organization "dedicated to developing and applying new technologies for monitoring and understanding the natural world, and sharing them with the public and the academic community." Roger Dellor serves as a vice-president of the organization; Thampy Thomas serves on its Board.
Ralph Merkle later became a noted nanotechnologist.
Thampy Thomas became a founder of NexGen, which was later acquired by AMD. The NexGen design became the design for the AMD K6 processor.
Mac McFarland was also an early NexGen employee. Mac's role in the design of the PDP-11 is given in Gordon Bell's history of DEC
B. V. Jagadeesh became a founder of Exodus Communications took it public in 1998 and became CEO of NetScaler in Aug 2000 and successfully sold to Citrix for $325M in 2005
Bob Rau and Arun Kumar became founders of Cydrome. Bob then worked at HP Labs and was one of the developers of the IA-64 architecture.
Allen Roberts and Harlan Lau became early employees of Rambus
John Sanguinetti founded Chronologic and wrote the VCS Verilog Compiler
Robert Olson became the founder of Virtual Vineyards, and later served as an engineering executive with several Internet-focused startups, such as PostX.
Mike Farmwald founded several Silicon Valley high tech companies.
