# Cray-1
The **Cray-1** was a vector supercomputer designed by [Seymour Cray](https://www.edgepedia.org/seymour-cray) and sold by [Cray Research](https://www.edgepedia.org/cray-research), Inc. from 1976; it was the first commercially successful vector processor and the fastest computer of its day, with a peak rate of 160 million floating-point operations per second (MFLOPS)[1](https://cray-history.net/wp-content/uploads/2021/08/Y-MP8D_red_redux.pdf) • [2](https://museum.ipsj.or.jp/en/computer/super/history.html). The first machine was shipped to the [Los Alamos National Laboratory](https://www.edgepedia.org/los-alamos-national-laboratory) on March 4, 1976 for a free six-month trial, and the National Center for Atmospheric Research (NCAR) became the company's first official customer[3](https://www.ebsco.com/research-starters/history/first-cray-1-supercomputer-shipped-los-alamos-national-laboratory/) • [4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1).
| Key fact | Detail |
|---|---|
| Introduction | Announced in 1976 by Cray Research (founded 1972); first unit shipped to Los Alamos National Laboratory on March 4, 1976 for a six-month trial[2](https://museum.ipsj.or.jp/en/computer/super/history.html) • [3](https://www.ebsco.com/research-starters/history/first-cray-1-supercomputer-shipped-los-alamos-national-laboratory/) |
| Clock and peak speed | 12.5-nanosecond clock period (80 MHz); chaining of vector add and multiply produced two FLOPs per clock, a peak of 160 MFLOPS[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) |
| Memory and registers | 1 million 64-bit words (8 megabytes) of semiconductor memory; eight 64-element 64-bit vector registers[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) |
| Physical design | C-shaped 270-degree arc of 12 wedge-shaped columns, 10,500 pounds (4.76 metric tons) at maximum memory; no wire longer than 4 feet; Freon cooling through stainless steel tubing[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf) • [6](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer) • [7](https://www.computerhistory.org/internethistory/1970s/) |
| Price and sales | Originally priced between $5 million and $8 million; about 80 units sold[8](https://www.hpcwire.com/off-the-wire/two-cray-supercomputers-join-living-computers/) |
| NCAR installation | Cray-1A serial number 3 arrived July 11, 1977 at a cost of $8.86 million; served nearly 12 years, until January 1989[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) • [6](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer) |
| Software | Cray Operating System, the first automatically vectorizing Fortran compiler (CFT), and Cray Assembly Language, introduced as a standard package in 1978[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) |
| Successors | Cray-1S added an integrated I/O subsystem; the Cray X-MP (1982) extended the architecture to multiple processors[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) • [9](https://www.cisl.ucar.edu/ncar-supercomputing-history/cx) |
## Architecture
The Cray-1 was the logical successor to the CDC 7600, the [Control Data Corporation](https://www.edgepedia.org/control-data-corporation) machine Seymour Cray had designed before founding his own company. The 7600's instruction-issue bottleneck limited it to one floating-point operation per clock; the Cray-1 overcame this with vector instructions, each of which caused a stream of up to 64 data elements to be processed from a single instruction issue[10](https://www.icsa.inf.ed.ac.uk/research/groups/hase/models/cray1/cray1.html). Its success rested on three advancements: a 12.5-nanosecond processor clock that doubled scalar processing over the CDC 7600, a vector implementation that improved performance over scalar processing by a factor of five to ten, and a large 1-Mword memory that freed programmers from explicitly allocating arrays in secondary fast memory[11](https://www.sciencedirect.com/science/article/pii/S0927545206800109).
**Registers and functional units.** The machine had five sets of operating registers. The eight V registers, each holding 64 elements of 64 bits, were the major computational registers; a typical vector instruction took operands from two V registers and returned results to a third, one element per clock period. Alongside them were eight 64-bit S (scalar) registers, eight 24-bit A (address) registers, and two buffer sets, 64 B registers backing the A registers and 64 T registers backing the S registers[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1) • [10](https://www.icsa.inf.ed.ac.uk/research/groups/hase/models/cray1/cray1.html). Twelve functional units operated concurrently, and each vector register had its own input multiplexer so that results could enter registers without colliding[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf) • [10](https://www.icsa.inf.ed.ac.uk/research/groups/hase/models/cray1/cray1.html).
**Chaining.** A result leaving a functional unit could re-enter as an operand of another vector operation in the same clock period, a mechanism the hardware detected automatically. Chaining let the Cray-1 produce more than one result per clock period; a floating-point add and a multiply chained together yielded two FLOPs per clock, or 160 MFLOPS at the 12.5-nanosecond clock period[12](https://ed-thelen.org/comp-hist/CRAY-1-HardRefMan/CRAY-1-HRM.html) • [10](https://www.icsa.inf.ed.ac.uk/research/groups/hase/models/cray1/cray1.html). Independent benchmark studies cited in Richard M. Russell's 1978 *Communications of the ACM* paper showed sustained rates of 138 MFLOPS, with short bursts of 250 MFLOPS[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf).
**Circuit technology.** The logic was built almost entirely from [emitter-coupled logic](https://www.edgepedia.org/emitter-coupled-logic) (ECL), using only a few chip types: 16-by-4-bit bipolar register chips with a 6-nanosecond cycle, 1024-by-1-bit bipolar memory chips with a 50-nanosecond cycle, and simple 5/4 [NAND gate](https://www.edgepedia.org/nand-gate) logic chips. Memory was organized in 16 banks and carried error detection and correction (SECDED) logic[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf).
## Physical design and cooling
The Cray-1's distinctive shape served its speed. A cylindrical form was chosen to keep wiring distances small: the mainframe consisted of 12 wedge-shaped columns arranged in a 270-degree arc, no wire was longer than 4 feet, and the short signal paths supported the 12.5-nanosecond clock[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf) • [7](https://www.computerhistory.org/internethistory/1970s/). The machine drew about 115 kW at maximum memory size and was cooled by Freon circulating through stainless steel tubing bonded within vertical aluminum wedges between the circuit boards, a bonding process Cray patented[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf) • [7](https://www.computerhistory.org/internethistory/1970s/). The padded bench that circled the base, nicknamed the "world's most expensive love-seat," hid the power supplies and cooling plumbing[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf) • [6](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer).
At maximum memory configuration the machine weighed 10,500 pounds (4.76 metric tons). NCAR's first production model was lowered into an underground expansion of its computing facility on July 11, 1977[6](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer).
## Software
When NCAR's machine was delivered, Cray Research was still completing its software; the company's development staff spent the latter half of 1977 working on site at NCAR. In 1978 Cray introduced its first standard software package: the Cray Operating System, the Cray Fortran Translator (CFT), and Cray Assembly Language[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1). CFT was an optimizing compiler that automatically vectorized innermost DO loops without source modifications or nonstandard statements, protecting users' existing Fortran investments[5](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf).
## Users and applications
The leading customers were the Los Alamos and Lawrence Livermore National Laboratories and NCAR[3](https://www.ebsco.com/research-starters/history/first-cray-1-supercomputer-shipped-los-alamos-national-laboratory/). The first major production code at Los Alamos became operational in May 1977[13](https://digital.library.unt.edu/ark%3A/67531/metadc1412349/).
At NCAR the machine's vector capability suited atmospheric science. Within a year, NCAR's Peter Gilman had run pioneering simulations of the solar dynamo, covering the Sun's rotation, magnetic fields, and subsurface convection zone; Albert Semtner and William Holland modeled large-scale ocean circulation; and researchers at several universities produced newly detailed thunderstorm models[6](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer). NCAR's Cray-1A throughput was estimated at about 4.5 times that of the CDC 7600 it joined, and the 7600 served as its front end for data handling[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1).
## Commercial impact and successors
About 80 Cray-1 systems were sold, at original prices between $5 million and $8 million, making it one of the most commercially successful supercomputers of its era[8](https://www.hpcwire.com/off-the-wire/two-cray-supercomputers-join-living-computers/) • [14](https://www.christies.com/en/lot/lot-6495044). It established vector processing as the standard for large-scale scientific computing, and vectorization techniques spread across scientific and engineering disciplines[1](https://cray-history.net/wp-content/uploads/2021/08/Y-MP8D_red_redux.pdf).
The product line evolved quickly. The original machine became known as the Cray-1A after the Cray-1S appeared with an integrated I/O subsystem[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1). The [Cray X-MP](https://www.edgepedia.org/cray-x-mp), whose two-processor prototype became operational early in 1982, kept Cray-1 source code upward compatible while adding shared central memory among processors and interprocessor communication hardware; its four-processor X-MP/48 reached a peak of 941 MFLOPS[9](https://www.cisl.ucar.edu/ncar-supercomputing-history/cx) • [15](https://homepages.inf.ed.ac.uk/rni/comp-arch/Vect/cray-xmp.html). The Cray Y-MP followed in 1988[16](https://www2.seas.gwu.edu/~mlancast/cs211al/Appendices/appendix_l.pdf). NCAR's first Cray-1A ran until January 27, 1989, nearly 12 years of service, the longest production lifetime of any of that center's supercomputers[4](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1).
## References
1. [The CRAY-MP Series of Computer Systems, Cray-History.net](https://cray-history.net/wp-content/uploads/2021/08/Y-MP8D_red_redux.pdf)
2. [Brief History of Supercomputers, Information Processing Society of Japan Computer Museum](https://museum.ipsj.or.jp/en/computer/super/history.html)
3. [First Cray-1 Supercomputer Is Shipped to the Los Alamos National Laboratory, EBSCO Research Starters](https://www.ebsco.com/research-starters/history/first-cray-1-supercomputer-shipped-los-alamos-national-laboratory/)
4. [CRI Cray-1A S/N 3, NCAR Computational and Information Systems Lab](https://www.cisl.ucar.edu/ncar-supercomputing-history/c1)
5. [Richard M. Russell, The CRAY-1 Computer System, Communications of the ACM 21(1), 1978 (Computer History Museum copy)](https://tcm.computerhistory.org/ComputerTimeline/Chap44_cray1_CS2.pdf)
6. [The Cray-1: Not your ordinary supercomputer, NCAR & UCAR News](https://news.ucar.edu/3266/cray-1-not-your-ordinary-supercomputer)
7. [Internet History, 1970s, Computer History Museum](https://www.computerhistory.org/internethistory/1970s/)
8. [Two Cray Supercomputers Join Living Computers, HPCwire](https://www.hpcwire.com/off-the-wire/two-cray-supercomputers-join-living-computers/)
9. [CRI Cray X-MP, NCAR Computational and Information Systems Lab](https://www.cisl.ucar.edu/ncar-supercomputing-history/cx)
10. [HASE Cray-1 Simulation Model, University of Edinburgh](https://www.icsa.inf.ed.ac.uk/research/groups/hase/models/cray1/cray1.html)
11. [The Balance of Power: A Brief History of Cray Research Hardware Architectures, ScienceDirect](https://www.sciencedirect.com/science/article/pii/S0927545206800109)
12. [CRAY-1 Hardware Reference Manual, Cray Research](https://ed-thelen.org/comp-hist/CRAY-1-HardRefMan/CRAY-1-HRM.html)
13. [Experience with the CRAY-1 Computer at the Los Alamos Scientific Laboratory, UNT Digital Library](https://digital.library.unt.edu/ark%3A/67531/metadc1412349/)
14. [A CRAY-1 Supercomputer, Cray Research, Inc., 1976-8, Christie's](https://www.christies.com/en/lot/lot-6495044)
15. [The CRAY X-MP, University of Edinburgh computer architecture notes](https://homepages.inf.ed.ac.uk/rni/comp-arch/Vect/cray-xmp.html)
16. [Cray X-MP and Y-MP overview, George Washington University course appendix](https://www2.seas.gwu.edu/~mlancast/cs211al/Appendices/appendix_l.pdf)
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*Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Computer hardware › Processors & processor engineering › Microprocessor families*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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