Seymour Cray

Seymour Cray

There are very few people in this ever-changing world of computers who have consistently achieved success, more than once, who created and shaped a whole new industry, and inspired many people. Seymour Cray was one of them. He tragically passed away on October 6, 1996, due to massive head injuries suffered in a car accident. He was considered one of the greatest computer designers and innovators in the world.

Seymour was involved in building computers since 1950 when he worked with ERA, which built UNIVAC, the first commercial computer. Later he co-founded CDC and developed the world's first vector processing computer CDC-650 in 1960, which was a huge commercial success. CDC-1604 was developed in the mid-1960s and it utilized transistors for the very first time. Then came CDC-6600 and CDC-7700; all of these were designed by Seymour. In 1972 Cray co-founded Cray Research and built the Cray-1, the world’s first supercomputer, which created a whole new industry, and the United States enjoyed dominance in high-performance computing for the next two decades. In later years, Cray-1 evolved into several different types of high-performance computers such as Cray-2, Cray X-MP, Cray Y-MP, Cray-3, Cray-C90, Cray-T90, Cray-T3D, and so on, using Seymour’s basic vector processing architecture.

Seymour Cray believed in two principles in building computers–simplicity and balance. The idea alone led to the inherently simple computer design, now called RISCs–Reduced Instruction Set Computers. CDC-650 was the world's first RISC computer, having only 80 instructions as compared to IBM-360’s which carried more than 300 instructions. Seymour was driven by a fascination to build the best and the fastest computers in the world. Although it sounds rather odd, he believed in individual effort in designing the key ideas of computer architecture; and he said “...Designing by committee is not appropriate for computers. You pretty much need one person to say, ‘this is the way it’s going to be for this machine...’. He admitted that he did need a lot of support from people to implement the design ideas. Another point of his good design was his ability to listen to the user. He improved his next machines after feedback from the customers, listening to their complaints, what they wanted in future machines, and then structuring the computer architecture based on their needs.

He always designed his computers from scratch, called the blank paper approach, using the latest technology available or even creating new ones. For example, he used transistors in place of vacuum tubes in CDC-1604; used Gallium Arsenide (GaAs) instead of traditional silicon for Cray-3, even though Gallium Arsenide was not available commercially at that time. Early in the 60s, it was discovered that a lot of mathematical puzzles such as differential equations and finite-element analysis can be solved using an iterative process and the accuracy of the result can be increased by increasing the number of iterations; that is where scientific computing starts evolving. Cray computers revolve around scientific computing in general, but in fact, they were the fastest scalar computers at that time! He believed in balance in the architecture–no part of the computer system slows down the entire computing process. Slow memories were a problem in designing computers as they are today. He designed what is considered textbook techniques. These techniques are still taught in computer architecture courses in colleges today.

Cray-1 came out in ‘75 using integrated circuits instead of discrete components as compared to Seymour’s previous designs. It was his first computer design using ICs. Cray-1 was a single processor computer with 1MW of memory, capable of sustaining 138 MFLOPS of computational rate. The vector unit designed by Seymour was so elegant that Cray Research applied for a patent, although he did not believe in patenting any of his designs. Apart from his technical innovations, he believed in the aesthetics of his machines which is carried on even today by Cray Research Inc. He believed the machine's appearance enhances its marketing opportunities. Most of the computers are air-cooled to keep the parts from overheating or even melting. Cray-1 was Freon cooled, like a refrigerator. Cray-2 and others go even further–they are liquid-cooled. These computers use fluorocarbon, also used as artificial blood in humans during surgical procedures, which is a non-conducting and breathable compound, as coolant.

Seymour Cray’s contribution to this country was to design the best computer that he could, to the best of his abilities, and he did exactly that. These computers are the most powerful ones in the world at that time and they all proudly bear his name. He took risks in designing new ideas and working with young people to build them. He won numerous awards, but never accepted any. His name will certainly hold a special place in the history of computers.

Sohail Shaikh

NVCC, Summer, 1997

Cray 1

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Cray 2

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Cray YM-P EL90

See the paper here