by Lynda Lester
Editor's note: This is one of a series of articles
covering talks given at the Ninth SCD User Conference,
held in June 1993 at the NCAR Mesa Laboratory in Boulder.
In May, a four-processor CRAY-3 joined the rosterof NCAR supercomputers.
Photo copyright (c) 1993 Stephen O. Gombosi, used with permission.
It's sleek, it's gray, it's a four-foot-tall postmodern cabinet. Through a clear acrylic case on top, interconnect wires can be seen waving like kelp in a sea current. The current is made of liquid coolant, which dissipates integrated-circuit heat; the computer is the world's first CRAY-3, designed by Seymour Cray and installed at NCAR in May.
In his talk "Introduction to the CRAY-3," Ron Larson of Cray Computer Corporation (CCC) used slides to show the manufacturing process for the electronic modules that make up the core of the CRAY-3.
Unlike conventional supercomputers, the CRAY-3 uses gallium arsenide (GaAs) for its logic circuits. CCC fabrication plants in Colorado Springs produce these logic circuits, as well as the printed circuit boards that go into the machine. During the production process, ultrasonic die bonders attach gold leads (tiny wire legs) to GaAs integrated circuit die. The leads of the die are then inserted through tiny holes in a one-inch-square printed circuit board and crushed, in a process that joins together die and boards. Sixteen die go on a board. Sixty-four boards, arranged in 16 stacks that are sandwiched around a set of four-inch-square plates, form a module; this packaging produces a logic density of 100 gates per cubic inch. Four modules comprise a processor. There are four processors in the CRAY-3 at NCAR.
Old and new computational tools: pencil and CRAY-3 module.
Photo copyright (c) 1993 Stephen O. Gombosi, used with permission.In addition to its processor modules, NCAR's CRAY-3 has 64 memory modules and 4 input/output modules. All these modules have a combined volume of 405 cubic inches and burn 88 kilowatts of power. "Eighty-eight kilowatts is a lot of energy to dissipate," Ron said, noting that the machine is filled with cooled Fluorinert that is pumped right through the component modules. "Now you know why Seymour is as good at refrigeration design as he is at computer logic."
The computer's two-nanosecond clock represents a tremendous advance in miniaturization and speed since the CRAY-1 hit the market in 1976--but it's only a preview of things to come. "I saw a quote from Seymour last week," Ron said, quoting the legendary inventor: "'As long as we can make them smaller, we can make them faster.'"
Bill Buzbee, left (SCD director and Seymour Cray, right (chairman and executive officer of Cray Computer Corporation) discuss the CRAY-3 supercomputer installed at NCAR in May. In recent months, NCAR has also installed a Connection Machine-5 from Thinking Machines Corporation and an IBM SP-1 cluster. (Photo by Bob Bumpas.)
This photo shows the processors and memory in the CRAY-3. When the machine is running, the entire assembly is immersed in liquid coolant. Photo copyright (c) 1993 Stephen O. Gombosi, used with permission.
Lynda Lester is a writer/editor in the Documentation Group within the SCD User Services Section.
