Editing Cray-2 (section)

{{Short description|1985 supercomputer model}}
{{Refimprove|date=September 2016}}
{{Infobox computer
| Photo         = [[File:CRAY-2 IMG 8915-8913-8912a.jpg|250px]]
| caption       = Cray-2 central unit (foreground) and [[Fluorinert]]-cooling "waterfall" (background), on display at the [[École Polytechnique Fédérale de Lausanne|EPFL]].
| Name          = Cray-2
| logo          = [[File:CRAY-2 IMG 8971.CR2-logo.jpg|250px]]
| manufacturer  = [[Cray Research]]
| Type          = [[Supercomputer]]
| Released      = {{Start date|1985}}
| Discontinued  = 1990
| units sold    = 25
| Processor     = Custom Vector Processors
| Memory        = 
| OS            = 
| predecessor   = [[Cray X-MP]]
}}
[[Image:Cray2.jpg|thumb|A Cray-2 and its [[Fluorinert]]-cooling "waterfall", formerly serial number 2101, the only 8-processor system ever made, for [[NERSC]]]]
[[Image:Cray2.jpeg|thumb|A Cray-2 operated by [[NASA]]]]
[[File:Cray-2-1985.jpg|thumb|Front view of 1985 [[Supercomputer]] Cray-2, [[Musée des Arts et Métiers]], [[Paris]]]]
[[File:1985-Cray-2-side-view.jpg|thumb|Side view of 1985 [[Supercomputer]] Cray-2, [[Musée des Arts et Métiers]], [[Paris]]]]
[[Image:EPFL CRAY-II 1.jpg|thumb|Detail of the upper part of the Cray-2]]
[[Image:EPFL CRAY-II 2.jpg|thumb|Inside of the Cray-2]]

The '''Cray-2''' is a [[supercomputer]] with four [[vector processor]]s made by [[Cray Research]] starting in 1985. At 1.9 [[FLOPS|GFLOPS]] peak performance, it was the fastest machine in the world when it was released, replacing the [[Cray X-MP]] in that spot. It was, in turn, replaced in that spot by the [[Cray Y-MP]] in 1988.

The Cray-2 was the first of [[Seymour Cray]]'s designs to successfully use multiple CPUs. This had been attempted in the [[CDC 8600]] in the early 1970s, but the [[emitter-coupled logic]] (ECL) [[transistor]]s of the era were too difficult to package into a working machine. The Cray-2 addressed this through the use of ECL [[integrated circuit]]s, packing them in a novel 3D wiring that greatly increased circuit density.

The dense packaging and resulting heat loads were a major problem for the Cray-2. This was solved in a unique fashion by forcing the electrically inert [[Fluorinert]] liquid through the circuitry under pressure and then cooling it outside the processor box. The unique "waterfall" cooler system came to represent high-performance computing in the public eye and was found in many informational films and as a movie prop for some time.

Unlike the original Cray-1, the Cray-2 had difficulties delivering peak performance. Other machines from the company, like the X-MP and Y-MP, outsold the Cray-2 by a wide margin. When Cray began development of the [[Cray-3]], the company chose to develop the [[Cray C90]] series instead. This is the same sequence of events that occurred when the 8600 was being developed, and as in that case, Cray left the company.