Elxsi

Elxsi Corporation
Company type	Private
Industry	Computer hardware, Minicomputers
Founded	1979
Founder	Joe Rizzi, Thampy Thomas
Defunct	1989
Fate	Withdrew from computer manufacturing; brand acquired by Tata Group
Successor	Tata Elxsi (brand)
Headquarters	Silicon Valley, United States
Area served	Worldwide
Key people	Joe Rizzi, Thampy Thomas, Gene Amdahl (owner from 1985)
Products	64-bit ECL processors, EMBOS operating system, minicomputers
Owner	Tata Group (after acquisition)
Parent	Trilogy venture fund (after 1985 acquisition)

Elxsi Corporation was an American minicomputer manufacturer established in 1979 in Silicon Valley by Joe Rizzi and Thampy Thomas. It is acknowledged as one of the earliest Silicon Valley startups helmed by an Indian entrepreneur. The company engineered a 64-bit Emitter Coupled Logic (ECL) processor operating with a 50-nanosecond clock cycle and a 25-nanosecond backplane bus. This processor incorporated IEEE floating-point arithmetic and introduced an innovative multiprocessor communication bus known as the Gigabus. Its CPU utilized a microcoded design that supported customizable instruction sets, running on the message-oriented EMBOS operating system.

History

The design of Elxsi’s architecture was influenced by former Stanford faculty members Len Shar and Balasubrimanian Kumar, alongside industry experts such as Harold McFarland, noted for his involvement with the PDP-11, and George Taylor, who contributed to the IEEE floating-point standard committee. In 1985, Gene Amdahl acquired the company using capital from the Trilogy venture fund. Prominent investors included the Tata Group and Arthur Rock.

As the computing industry increasingly shifted focus from mainframes to personal computers, Elxsi withdrew from the computer manufacturing sector in 1989. The Tata Group maintained ownership of the Elxsi brand through Tata Elxsi, which is now integrated into its global enterprise. Following this exit, Elxsi divested its computer maintenance operations to National Computer Systems and expanded into other markets such as restaurant management systems and sewer inspection technology via its CUES division.

Elxsi’s hardware growth strategy initially found success within technical computing fields. Its 64-bit registers combined with parallel processing capabilities provided notable performance benefits on COBOL benchmarks, surpassing some mainframe systems. The CPU architecture—characterized by independent processors lacking cache snooping and featuring cache partitioning support—was well-suited for real-time applications, strengthening its position before ceasing hardware production.

Hardware

The system was classified as a mini-supercomputer, positioned size-wise between a VAX 11/780 and a mainframe. This particular segment diminished as advanced microprocessor-based high-end systems emerged.

Its architecture was unique, utilizing a system bus that linked up to 12 CPUs and I/O processors. Each CPU consisted of three substantial ECL gate array boards. Important architectural aspects included:

Sixteen registers (64-bit)
32-bit linear address space (supporting 64-bit integers and 32-bit pointers)
Multiple register sets per CPU with process switching managed by microcode
Restricted basic addressing modes and fixed instruction lengths
Lack of hardware cache coherence between processors
Microcoded messaging mechanisms for inter-processor and I/O communication
No traditional supervisor mode, substituted by regulated message link access and memory mapping
Several hardware CPU interrupts designed for real-time uses such as flight simulators and industrial control systems
Two generations of CPUs were marketed; a third generation was developed but never sold, all compatible with the same backplane

Software

The EMBOS operating system was created entirely from the ground up using an extended dialect of Pascal. It featured a multi-server design that anticipated later projects like GNU Hurd. Its user interface resembled Unix at the shell level but employed different commands (for example, "files" instead of "ls"). Subsequently, a Unix kernel was implemented above lower-level servers, allowing EMBOS and Unix processes to run concurrently (referred to as ENIX). Additionally, software compatibility with VMS enabled easier porting of applications originally developed for the VAX platform.

Noteworthy Personnel

Loren Kohnfelder, the pioneer behind the concept of the digital certificate, subsequently played a key role in enhancing security features for Microsoft Internet Explorer.
Ralph Merkle, who developed the Elxsi Fortran compiler, later gained recognition as a leading figure in nanotechnology.
Bob Rau, a co-founder of Cydrome, made significant contributions at HP Labs and was instrumental in the creation of the IA-64 processor architecture.

References

Notes

John Sanguinetti and B. Kumar, "Performance of a Message-Based Multi-Processor," Proceedings of the 12th International Symposium on Computer Architecture (12th ISCA'85), IEEE, Boston, MA, June 1985, pp. 424–425.
Gary R. Montry and Robert E. Benner, "Parallel Processing on an ELXSI 6400," Second International Conference on Supercomputing, Supercomputing '87, vol. II, International Supercomputing Institute, 1987, pp. 64–71.
Robert Olson, "Parallel processing in a message-based operating system," IEEE Software, vol. 2, 4, July 1985, pp. 39–49.
George S. Taylor, "Arithmetic on the Elxsi System 6400," Proceedings of the IEEE Sixth Symposium on Computer Arithmetic (1983), IEEE Computer Society, pp. 110–115.

External links