The Cray - 2 was a vector supercomputer, which was offered by Cray Research in 1985. She was the further development of the Cray -1 and its release of the world's fastest computer.


The Cray -2 was reduced in comparison with the Cray -1 to 135 cm maximum height and 115 cm in diameter, and shortens the cycle time to 4.1 nanoseconds. The cooling was done by means of Fluorinert, 3M developed a mixture of fluorocarbons. The coolant weighed a third of the 2.5 tonnes of computer.

Each processor had a maximum output of 488 MFLOPS, thus increasing the power totaled 1,951 GFLOPS at maximum configuration of four processors at 244 MHz.

The Cray - 2 has a foreground processor for I / O handling, synchronization of said background processors and to perform system tasks. The processors consist of silicon. Although Seymour Cray tried to create processors of gallium arsenide, but these processors were not yet ready for use as the Cray - 2 was developed.

The address registers were extended to 32 bits, and had a Cray -2 in the basic version 4 gigabytes of DRAM memory with 56 ns access time. In this case, interleaving was used in the memory modules 64 or 128 have been polled in turn. Later versions of the extended address space, so that a total of 32 gigabytes could be addressed.

Loading and saving of 64 vector data per processor took 63 cycles, while a calculation required only 22-23 cycles. To limit this problem, each processor with 128 KB of additional memory was associated with only four bars access time. However, this was not a real cache because of memory instead of merely registers have been cached.

Several Cray -2 could be connected together via a special 1.6 - Gbit / s network. The Cray -2 had in-house competition from the X -MP and Y - MP series, which reached the same computing power with more processors.


The Cray -2 was primarily used by the Defense Department and the Department of Energy of the United States. However, they also found more customers worldwide. Among other things, was acquired in 1986 by the German state of Baden- Württemberg, a Cray -2 for the University of Stuttgart, where it was up to April 1994 in use. These were the first Cray -2 in Europe.

System Information