The invention: A computer that had the greatest computational power that then existed.
The person behind the invention:
Seymour R. Cray (1928-1996), American computer architect and designer
The Need for Computing Power
Although modern computers have roots in concepts first proposed in the early nineteenth century, it was only around 1950 that they became practical. Early computers enabled their users to calculate equations quickly and precisely, but it soon became clear that even more powerful computers—machines capable of receiving, computing, and sending out data with great precision and at the highest speeds— would enable researchers to use computer “models,” which are programs that simulate the conditions of complex experiments.
Few computer manufacturers gave much thought to building the fastest machine possible, because such an undertaking is expensive and because the business use of computers rarely demands the greatest processing power. The first company to build computers specifically to meet scientific and governmental research needs was Control Data Corporation (CDC). The company had been founded in 1957 by William Norris, and its young vice president for engineering was the highly respected computer engineer Seymour R. Cray. When CDC decided to limit high-performance computer design, Cray struck out on his own, starting Cray Research in 1972. His goal was to design the most powerful computer possible. To that end, he needed to choose the principles by which his machine would operate; that is, he needed to determine its architecture.
The Fastest Computer
All computers rely upon certain basic elements to process data. Chief among these elements are the central processing unit, or CPU (which handles data), memory (where data are stored temporarily before and after processing), and the bus (the interconnection between memory and the processor, and the means by which data are transmitted to or from other devices, such as a disk drive or a monitor). The structure of early computers was based on ideas developed by the mathematician John von Neumann, who, in the 1940′s, conceived a computer architecture in which the CPU controls all events in a sequence: It fetches data from memory, performs calculations on those data, and then stores the results in memory. Because it functions in sequential fashion, the speed of this “scalar processor” is limited by the rate at which the processor is able to complete each cycle of tasks.
Before Cray produced his first supercomputer, other designers tried different approaches. One alternative was to link a vector processor to a scalar unit. A vector processor achieves its speed by performing computations on a large series of numbers (called a vector) at one time rather than in sequential fashion, though specialized and complex programs were necessary to make use of this feature. In fact, vector processing computers spent most of their time operating as traditional scalar processors and were not always efficient at switching back and forth between the two processing types.
Another option chosen by Cray’s competitors was the notion of “pipelining” the processor’s tasks. A scalar processor often must wait while data are retrieved or stored in memory. Pipelining techniques allow the processor to make use of idle time for calculations in other parts of the program being run, thus increasing the effective speed. A variation on this technique is “parallel processing,” in which multiple processors are linked. If each of, for example, eight central processors is given a portion of a computing task to perform, the task will be completed more quickly than the traditional von Neumann architecture, with its single processor, would allow.
Ever the pragmatist, however, Cray decided to employ proved technology rather than use advanced techniques in his first supercomputer, the Cray 1, which was introduced in 1976. Although the Cray 1 did incorporate vector processing, Cray used a simple form of vector calculation that made the technique practical and easy to use. Most striking about this computer was its shape, which was far more modern than its internal design. The Cray 1 was shaped like a
Seymour R. Cray
Seymour R. Cray was born in 1928 in Chippewa Falls, Wisconsin. The son of a civil engineer, he became interested in radio and electronics as a boy. After graduating from high school in 1943, he joined the U.S. Army, was posted to Europe in an infantry communications platoon, and fought in the Battle of the Bulge. Back from the war, he pursued his interest in electronics in college while majoring in mathematics at the University of Minnesota. Upon graduation in 1950, he took a job at Engineering Research Associates. It was there that he first learned about computers. In fact, he helped design the first digital computer, UNIVAC.
Cray co-founded Control Data Corporation in 1957. Based on his ideas, the company built large-scale, high-speed computers. In 1972 he founded his own company, Cray Research Incorporated, with the intention of employing new processing methods and simplifying architecture and software to build the world’s fastest computers. He succeeded, and the series of computers that the company marketed made possible computer modeling as a central part of scientific research in areas as diverse as meteorology, oil exploration, and nuclear weapons design. Through the 1970′s and 1980′s Cray Research was at the forefront of supercomputer technology, which became one of the symbols of American technological leadership.
In 1989 Cray left Cray Research to form still another company, Cray Computer Corporation. He planned to build the next generation supercomputer, the Cray 5, but advances in microprocessor technology undercut the demand for supercomputers. Cray Computer entered bankruptcy in 1995. Ayear later he died from injuries sustained in an automobile accident near Colorado Springs, Colorado.
cylinder with a small section missing and a hollow center, with what appeared to be a bench surrounding it. The shape of the machine was designed to minimize the length of the interconnecting wires that ran between circuit boards to allow electricity to move the shortest possible distance. The bench concealed an important part of the cooling system that kept the system at an appropriate operating temperature.
The measurements that describe the performance of supercomputers are called MIPS (millions of instructions per second) for scalar processors and megaflops (millions of floating-point operations per second) for vector processors. (Floating-point numbers are numbers expressed in scientific notation; for example, 1027.) Whereas the fastest computer before the Cray 1 was capable of some 35 MIPS, the Cray 1 was capable of 80 MIPS. Moreover, the Cray 1 was theoretically capable of vector processing at the rate of 160 megaflops, a rate unheard of at the time.
Consequences
Seymour Cray first estimated that there would be few buyers for a machine as advanced as the Cray 1, but his estimate turned out to be incorrect. There were many scientists who wanted to perform computer modeling (in which scientific ideas are expressed in such a way that computer-based experiments can be conducted) and who needed raw processing power.
When dealing with natural phenomena such as the weather or geological structures, or in rocket design, researchers need to make calculations involving large amounts of data. Before computers, advanced experimental modeling was simply not possible, since even the modest calculations for the development of atomic energy, for example, consumed days and weeks of scientists’ time. With the advent of supercomputers, however, large-scale computation of vast amounts of information became possible. Weather researchers can design a detailed program that allows them to analyze complex and seemingly unpredictable weather events such as hurricanes; geologists searching for oil fields can gather data about successful finds to help identify new ones; and spacecraft designers can “describe” in computer terms experimental ideas that are too costly or too dangerous to carry out. As supercomputer performance evolves, there is little doubt that scientists will make ever greater use of its power.
See also Apple II computer; BINAC computer; Colossus computer; ENIAC computer; IBM Model 1401 computer; Personal computer; UNIVAC computer.
