CRI Cray-1A S/N 3

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Cray Supercomputer

Cray Research, Inc.
In use: July 11, 1977 - February 1, 1989
Experimental and production use
Peak teraflops: 0.00
Processors: 1.00
Clock speed: 0.08GHz
Memory: 0.00TB
Electrical power consumption: 115.00 kW
Predecessor: CDC 7600
Paired with: CDC 7600
Successor: CRI Cray-1A S/N 14

In 1974, the outlook for computational capability beyond NCAR's Control Data Corporation (CDC) 7600 was dismal. The CDC STAR, the Texas Instruments ASC, and the ILLIAC IV all seemed unsuitable in the NCAR environment. Thus, wondering what had become of Seymour Cray after his departure from CDC, two SCD staff members made a trip to the Cray Research, Inc. Halley Laboratory in Chippewa Falls, Wisconsin, to "see what Seymour was up to."

Cray Research, Inc. (CRI) had been founded two years earlier by Seymour Cray after he left Control Data Corporation.  As CRI's architect, Seymour provided the technical vision of a Cray-1 computer with a clock speed that was twice at least as fast as the CDC 7600 and demonstrated balanced scalar and vector performance. The computer was also innovative in its use of reciprocal approximation for division. Although the Cray-1 was still only partially built at the time of the visit, it was apparent that the design reflected a simplicity not found in the other computers. The CF team felt that although many technical and financial objections had to be overcome, the CRAY-1 would be a viable upgrade to the CDC 7600.

By 1975, NCAR's 7600 was straining under a severe workload, it was oversubscribed and turnaround time had become intolerable. A request for proposal (RFP) was issued later that year for the acquisition of a "fifth-generation computer".  The RFP and subsequent negotiations resulted in UCAR's order for a Cray-1 system from CRI. While serial number 1 of the Cray-1 computer system had been shipped to the Los Alamos National Laboratory in 1976 for a six-month trial period, NCAR was Cray Research's first official customer.  While the Cray Research computer was, at the time, called the Cray-1, it later became known as the Cray-1A, to differentiate it from the follow-on Cray-1S computer which had an integrated I/O subsystem.

On July 11, 1977, the Cray-1A, serial number 3, was delivered to NCAR. The system cost was $8.86 million ($7.9 million for the system, plus $1 million for the disks).

The supercomputer weighed 5-1/2 tons, arrived in two refrigerated electronic vans, and needed more than 30 construction workers, engineers, and helpers to move it into the computer room. NCAR accepted the Cray-1A in December. It was the first Cray-1A to go into production, and upon its acceptance, Cray Research became a revenue-generating company.

The Cray-1A was very stable compared to the CDC 7600, representing a significant improvement in mean-time-to-failure rates. In good times, the 7600 hardware or software had failed at least once a day, often four to five or more times, wheras the CRAY would run for several days and most often failed only because of disk problems.

The CDC 7600 was used as a front end to the Cray-1A. Incoming work flowed through the 7600, which also retrieved necessary archival files for use on the Cray from NCAR's TeraBit Memory (TBM) tape-based mass storage system. Users migrated their jobs to the Cray rather slowly at first, and continued to use the 7600 for data handling chores.

NCAR's Cray-1A, S/N 3, had a 12.5-nanosecond clock, eight 64-element vector registers, 1 million 64-bit words (8 megabytes) of high-speed memory and sixteen DD-19 "high-speed" disk drives, each with a capacity of three-hundred megabytes and a transfer rate of 4.5 megabytes per second. The Cray-1A could chain floating-point vector add and mutliply instructions together to produce two floating point operations (FLOPs) per clock; thus the Cray-1A had a peak speed of 160 megaflops.  Overall, the throughput of NCAR's Cray-1A was estimated to be about 4.5 times that of its CDC 7600.

When NCAR's first Cray-1A was delivered, CRI was still working on its operating system, Fortran compiler and other software.  Staff members of Cray's software development organization spent the latter half of 1977 on site at NCAR doing development work, and in 1978, Cray's first standard software package consisting of the Cray Operating System (COS), the first automatically vectorizing Fortran compiler, the Cray Fortran Translator (CFT), and the Cray Assembler Language (CAL) were introduced.

The Cray-1A's design, and vector processing capability, was particularly adapted to the needs of the scientific community, and permitted significant advances in the modeling of climate and severe storms.

In 1980, during the Cray-1A's time at NCAR, the NCAR Computing Facility (CF), formerly a part of NCAR's Atmospheric Technology Division (ATD), was reorganized as the Scientific Computing Division (SCD) of NCAR.

NCAR's Cray-1A, S/N 3, was removed from user production on January 27, 1989 and powered off on February 1, after nearly 12 years of service - the longest production lifetime of any of NCAR's supercomputers.

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