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Cray-2 supercomputer proves to be powerful tool, but is under-utilized

By Joan Abbott

MIT users have had access to a Cray-2 supercomputer facility since July, but not as many have utilized it as had been expected. "It can handle many more clients than it currently does," said Edward M. Andrews, the facility's administrative officer.

Cray Research Inc. provides a substantial amount of funding for the program in the form of yearly research grants for work done on supercomputers.

With four central processors and 256 million 64-bit words of random access memory, the Cray-2 provides high speed computations at relatively low cost. The supercomputer clock period, the time needed for one computational cycle, is 4.1 nanoseconds -- one of the fastest periods available.

The cost to users is $140 per central-processing unit hour. There is no minimum amount of computer time that users may purchase -- one hour can be bought just as easily as 100 hours, allowing beginners to gain access to the Cray-2 without a huge initial financial investment.

The cost of using the Cray-2 is relatively low because it is being used simply as a computational server, dependent on the existing system, rather than as a full-functioning supercomputer. The Cray-2 is integrated into the existing MIT system, allowing users to perform supercomputer calculations from their workstations while using Athena printers and plotters.

UNICOS, the Cray-2 operating system, may be familiar to Athena users since it is a Cray version of UNIX. Pascal, Fortran, and C compilers are available on the system along with CAL, the Cray assembler. In addition, members of the MIT community may request that additional software be purchased for the Cray-2 by submitting requests to the MIT supercomputing facility.

Tetsu Hara, a graduate student in civil engineering, recently incorporated the Cray-2 into his research project. He is developing a model of wind and wave motion in bodies of water. Trials of his model, which took seven hours or longer on a Microvax II, now takes two or three minutes on the Cray-2, he said.

While the Cray-2 is intended primarily for research, it can also be used for coursework. Cray Research donated 2000 hours of computing time during the first year to be used for course-related activities. At this time, the Cray-2 is not being used widely in undergraduate coursework.

Michael B. Giles, assistant professor of aeronautics and astronautics, plans to use the Cray-2 next term in a graduate course in advanced computational fluid mechanics. "I plan to use the Cray-2 as more than a number cruncher," he said. "The students can learn to program algorithms necessary to run on this type of computer."

Getting an account on the Cray-2 is relatively simple. Research projects can obtain a Cray-2 account in about 24 hours by submitting a request form, a brief description of the project, and a requisition for the cost of the computer time. Course projects require a short proposal, an assessment of the number of hours that the course will require, and administrative work for individual students who will be using the machines.