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Inside view of a Cray-2

The Cray-2 was a vector supercomputer offered by Cray Research in 1985. It was the further development of the Cray-1 and when it appeared it was the world's fastest computer.


Compared to the Cray-1, the Cray-2 has been reduced to a maximum height of 135 cm and a diameter of 115 cm, and the cycle time has been shortened to 4.1 nanoseconds . The cooling was done using Fluorinert , a mixture of fluorocarbons developed by 3M . The coolant weighed a third of the 2.5 ton machine.

Each processor had a maximum output of 488 MFLOPS at 244 MHz , which means that with a maximum expansion of four processors, the output totaled 1.951 GFLOPS. For comparison: the Apple Watch from 2015 has almost twice the computing power of the Cray-2.

The Cray-2 has a foreground processor for I / O handling, synchronization of the background processors mentioned and for performing system tasks. The processors are made of silicon . Seymour Cray tried to make processors from gallium arsenide , but these processors were not ready for use when the Cray-2 was developed.

The address registers were expanded to 32 bits, and the basic version of a Cray-2 had 4 gigabytes of DRAM memory with an access time of 56  ns . It was interleaving used in which 64 or 128 memory modules have been scanned sequentially. Later versions expanded the address space so that a total of 32 gigabytes could be addressed.

Loading and saving 64 vector data per processor took 63 cycles, while a calculation only required 22 to 23 cycles. To limit this problem, each processor was connected to an additional 128 Kbytes of memory with only four clocks access time. However, this was not a real cache , as only registers were cached instead of main memory .

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


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

System information

Parameter Data
Machine type Shared memory multi- vector processor
operating system Unicos ( Unix variant from Cray Computer Corporation)
Compiler Fortran , C.
Cycle time 4.1 ns
Processor memory 128 KB
Theoretical maximum performance per processor 488 MFLOPS
Maximum theoretical performance (four processors) 1,951 GFLOPS
Main memory 4-32 GB
Memory bandwidth of each processor 1.95 GB / s
Number of processors 1-4

Web links

Commons : Cray-2  - collection of images, videos and audio files

Individual evidence

  1. ^ A Supercomputer on Your Wrist: Infographic Series Shows Moore's Law in Action. (No longer available online.) In: Archived from the original on March 29, 2016 ; accessed on March 29, 2016 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  2. a b Land buys the best computer in the world . In: Badische Zeitung . July 19, 1985. Quoted from: Newspaper Yearbook Germany . tape 3, 1985/86 . Kastell Verlag, 1986, ISBN 3-924592-06-3 , ISSN  0177-7831 , p. 161 .
  3. Daily mix September 28th . Retrieved on January 1, 2013.  ( Page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Dead Link /