The Cray-1: Not your ordinary supercomputer

NCAR’s Mesa Laboratory saw thousands of comings and goings in its first few years, but only one arrival needed a new room to accommodate it. Workers gently lowered the first production model of the Cray-1 supercomputer—which tipped the scales at 10,500 pounds (4.76 metric tons)—into an underground expansion of NCAR’s computing facility on 11 July 1977. In the understated words of Cray engineer Bill King, one of several self-dubbed “Crayons” on hand to smooth the way, “We plugged it in and turned it on and it worked.”

Photo of men installing a supercomputer

Seymour Cray had designed NCAR’s first two supercomputers, the Control Data 6600 and 7600, before launching his own firm. NCAR was the first center to purchase his company’s debut machine, the Cray-1. With the help of newly designed integrated silicon chips, the Cray-1 boasted more memory (one megabyte) and more speed (80 million computations per second) than any other computer in the world.

The Cray’s bold look also set the machine apart. Its orange-and-black tower, curved to maximize cooling, was surrounded by a semicircle of padded seats—dubbed an “inverse conversation pit” by one observer—that hid the computer’s power supplies.

Scientists wasted no time putting the Cray to work. Within a year, NCAR’s Peter Gilman had carried out pioneering simulations of the solar dynamo, including the Sun’s rotation, its magnetic fields, and the zone of convection beneath its surface. Albert Semtner and William Holland explored the large-scale circulation of ocean basins. Newly detailed models of thunderstorms were produced by scientists from the University of Illinois at Urbana-Champaign (see page 26), Colorado State University, and the University of Hawaii. And from Pennsylvania State University, Richard Anthes (later the director of NCAR and president of UCAR) worked on the pioneering and widely used Penn State¬–NCAR Mesoscale Model series.

Photo of a woman working with magnetic tapes for a computer
Output from the Cray-1 was stored on magnetic tapes, each of which weighed about 6.4 kilograms (14 pounds) and held about 5 billion bytes of data (5 gigabytes).

During NCAR’s first decade, only a few university faculty could afford trips to Boulder for the tedious task of running and rerunning code in person on NCAR machines. Things changed in the 1970s as a remote job-entry system—now standard practice, but revolutionary for its day—allowed researchers to submit code and get results over fledgling computer networks. By the time the Cray-1 was installed, scientists at more than 40 universities were using the remote system. Today, users at more than 110 U.S. universities access NCAR’s computers each year.

All the number-crunching would have been for naught without someplace to put the results. A few months before the Cray-1 arrived, NCAR acquired a new videotape-based Ampex data storage system. With hundreds of tapes, each holding 5 gigabytes (5 billion bytes), the system allowed data to be brought online as needed and to be stored safely at other times.

Subsequent NCAR supercomputers have long eclipsed the Cray-1. In 2008, NCAR accepted delivery of the world’s first operational IBM Power 575, which packed more than a million times more computing power. Yet the Cray, with its unprecedented prowess, served its many users well.

“Everything was done with card decks that you had to submit,” recalled Robert Street (Stanford University), a UCAR trustee in the 1980s and 1990s. As a postdoctoral researcher at NCAR in 1978–79, Street discovered that most staff used the Cray during the daytime: “I could go up there about 11 at night, stay till 4 in the morning, and get all the computer runs I ever wanted.”


Today — A new home for NCAR computing

Photo of Krista Laursen

"Our goal is to set the standard for supercomputing center energy efficiency."

—Krista Laursen, NWSC project director

Southeast Wyoming will host some of the most powerful computers in atmospheric research when the NCAR-Wyoming Supercomputing Center (NWSC) opens in Cheyenne. The $70 million center, funded by NSF with the state of Wyoming and the University of Wyoming, is being developed through a partnership with several state and local organizations. The NWSC stands to raise Wyoming’s high-tech profile while providing a major boost to NCAR and university science. Groundbreaking took place on 15 June 2010.

After some 40 years at the Mesa Lab, NCAR’s computing facility began to face inherent limits to its location. Not only was space tight on the mesa, but the site’s electrical supply was inadequate to operate and cool the high-powered supercomputers expected to arrive in coming years. After considering a range of options, NSF and NCAR settled on a Wyoming site that could stimulate local science and technology while allowing for the most computing power per taxpayer dollar—a win-win solution.

Given NCAR’s legacy of environmental research and stewardship, NWSC planners are striving to make it a leader in energy efficiency. Wyoming’s cool climate is a helpful starting point. The building’s planned architecture, designed for sustainability, means that as little as 10% or less of total power supply will be needed for heating, cooling, and lighting, with the rest going to computer operations. If achieved, this could make the NWSC one of the most efficient large computing centers in the world.

Along with supercomputers, the center will host NCAR’s data storage and access facilities, with ample room for growth. Staff in Cheyenne will remain in close contact with their Boulder-based colleagues through high-bandwidth videoconferencing as well as phone and e-mail links. For the hundreds of university scientists who access NCAR supercomputers, a brief transition period will give way to enhanced capabilities for years to come.

Artist's portrayal of a building
The future NCAR-Wyoming Supercomputing Center is being built in the North Range Business Park in Cheyenne, Wyoming. (Photo courtesy NCAR-Wyoming Supercomputing Center.)