Cray-2
Encyclopedia
The Cray-2 was a four-processor ECL vector
Vector processor
A vector processor, or array processor, is a central processing unit that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors. This is in contrast to a scalar processor, whose instructions operate on single data items...
supercomputer
Supercomputer
A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...
made by Cray Research
Cray
Cray Inc. is an American supercomputer manufacturer based in Seattle, Washington. The company's predecessor, Cray Research, Inc. , was founded in 1972 by computer designer Seymour Cray. Seymour Cray went on to form the spin-off Cray Computer Corporation , in 1989, which went bankrupt in 1995,...
starting in 1985. It was the fastest machine in the world when it was released, replacing the Cray Research
Cray
Cray Inc. is an American supercomputer manufacturer based in Seattle, Washington. The company's predecessor, Cray Research, Inc. , was founded in 1972 by computer designer Seymour Cray. Seymour Cray went on to form the spin-off Cray Computer Corporation , in 1989, which went bankrupt in 1995,...
X-MP
Cray X-MP
The Cray X-MP was a supercomputer designed, built and sold by Cray Research. It was announced in 1982 as the "cleaned up" successor to the 1975 Cray-1, and was the world's fastest computer from 1983 to 1985...
designed by Steve Chen in that spot. The Cray-2 was capable of 1.9 GFLOPS
FLOPS
In computing, FLOPS is a measure of a computer's performance, especially in fields of scientific calculations that make heavy use of floating-point calculations, similar to the older, simpler, instructions per second...
peak performance and was only bumped off of the top spot by the ETA-10G
ETA10
The ETA10 was a line of vector supercomputers designed, manufactured, and marketed by ETA Systems, a spin-off division of Control Data Corporation . The ETA10 was announced in 1986, with the first deliveries made in early 1987...
in 1990.
Initial design
With the successful launch of his famed Cray-1Cray-1
The Cray-1 was a supercomputer designed, manufactured, and marketed by Cray Research. The first Cray-1 system was installed at Los Alamos National Laboratory in 1976, and it went on to become one of the best known and most successful supercomputers in history...
, Seymour Cray
Seymour Cray
Seymour Roger Cray was an American electrical engineer and supercomputer architect who designed a series of computers that were the fastest in the world for decades, and founded Cray Research which would build many of these machines. Called "the father of supercomputing," Cray has been credited...
turned to the design of its successor. By 1979 he had become fed up with management interruptions in what was now a large company, and as he had done in the past, decided to resign his management post and move to form a new lab. As with his original move to Chippewa Falls, Wisconsin
Chippewa Falls, Wisconsin
Chippewa Falls is a city located on the Chippewa River in Chippewa County in the U.S. state of Wisconsin. The population was 13,661 at the 2010 census. Incorporated as a city in 1869, it is the county seat of Chippewa County....
from Control Data HQ in Minneapolis, MN, Cray management understood his needs and supported his move to a new lab in Boulder, Colorado
Boulder, Colorado
Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of...
. Working as an independent consultant at these new Cray Labs, he put together a team and started on a completely new design. This Lab would later close, and a decade later a new facility in Colorado Springs would open.
Cray had previously attacked the problem of increased speed with three simultaneous advances: more functional units to give the system higher parallelism, tighter packaging to decrease signal delays, and faster components to allow for a higher clock speed. The classic example of this design is the CDC 8600
CDC 8600
The CDC 8600 was the last of Seymour Cray's supercomputer designs while working for the Control Data Corporation. The "natural successor" to the CDC 6600 and CDC 7600, the 8600 was intended to be about 10 times as fast as the 7600, already the fastest computer on the market.Development started in...
, which packed four CDC 7600
CDC 7600
The CDC 7600 was the Seymour Cray-designed successor to the CDC 6600, extending Control Data's dominance of the supercomputer field into the 1970s. The 7600 ran at 36.4 MHz and had a 65 Kword primary memory using core and variable-size secondary memory...
-like machines based on ECL logic
Emitter coupled logic
In electronics, emitter-coupled logic , is a logic family that achieves high speed by using an overdriven BJT differential amplifier with single-ended input, whose emitter current is limited to avoid the slow saturation region of transistor operation....
into a 1 x 1 meter cylinder and ran them at an 8 ns
Orders of magnitude (time)
-Seconds:- See also :* Heat Death* Second law of thermodynamics* Big Rip* Big Crunch* Big Bounce* Big Bang* Cyclic model* Dyson's eternal intelligence* Final anthropic principle* Ultimate fate of the Universe* Timeline of the Big Bang...
cycle speed (125 MHz). Unfortunately the density needed to achieve this cycle time led to the machine's downfall. The circuit boards inside were densely packed, and since even a single malfunctioning transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
would cause an entire module to fail, packing more of them onto the cards greatly increased the chance of failure.
One solution to this problem, one that most computer vendors had already moved to, was to use integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s (ICs) instead of individual components. Each IC included a selection of components from a module pre-wired into a circuit by the automated construction process. If an IC did not work, another one would be tried. At the time the 8600 was being designed the simple MOSFET
MOSFET
The metal–oxide–semiconductor field-effect transistor is a transistor used for amplifying or switching electronic signals. The basic principle of this kind of transistor was first patented by Julius Edgar Lilienfeld in 1925...
-based technology did not offer the speed Cray needed. Relentless improvements changed things by the mid-1970s, however, and the Cray-1
Cray-1
The Cray-1 was a supercomputer designed, manufactured, and marketed by Cray Research. The first Cray-1 system was installed at Los Alamos National Laboratory in 1976, and it went on to become one of the best known and most successful supercomputers in history...
had been able to use newer ICs and still run at a respectable 12.5 ns (80 MHz). In fact, the Cray-1 was actually somewhat faster than the 8600 because it packed considerably more logic into the system due to the IC's small size.
Although IC design continued to improve, the physical size of the ICs was constrained largely by mechanical limits; the resulting component had to be large enough to solder into a system. Dramatic improvements in density were possible, as the rapid improvement in microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
design was showing, but for the type of ICs used by Cray, ones representing a very small part of a complete circuit, the design had plateaued. In order to gain another 10-fold increase in performance over the Cray-1, the goal Cray aimed for, the machine would have to grow more complex. So once again he turned to an 8600-like solution, doubling the clock speed through increased density, adding more of these smaller processors into the basic system, and then attempting to deal with the problem of getting heat out of the machine.
Another design problem was the increasing performance gap between the processor and main memory. In the era of the CDC 6600
CDC 6600
The CDC 6600 was a mainframe computer from Control Data Corporation, first delivered in 1964. It is generally considered to be the first successful supercomputer, outperforming its fastest predecessor, IBM 7030 Stretch, by about three times...
memory ran at the same speed as the processor, and the main problem was feeding data into it. Cray solved this by adding ten smaller computers to the system, allowing them to deal with the slower external storage (disks and tapes) and "squirt" data into memory when the main processor was busy. This solution no longer offered any advantages; memory was large enough that entire data sets could be read into it, but the processors ran so much faster than memory that they would often spend long times waiting for data to arrive. Adding four processors simply made this problem worse.
To avoid this problem the new design banked memory and two sets of registers (the B- and T-registers) were replaced with a 16 KWord block of the very fastest memory possible called a Local Memory, not a cache, attaching the four background processors to it with separate high-speed pipes. This Local Memory was fed data by a dedicated foreground processor which was in turn attached to the main memory through a Gbit/s channel per CPU; X-MPs by contrast had 3, for 2 simultaneous loads and a store and Y-MP/C-90s had 5 channels to avoid the von Neumann bottleneck. It was the foreground processor's task to "run" the computer, handling storage and making efficient use of the multiple channels into main memory. It drove the background processors by passing in the instructions they should run via eight 16 word buffers, instead of tying up the existing cache pipes to the background processors. Modern CPUs use a variety of this design as well, although the foreground processor is now referred to as the load/store unit and is not a complete machine unto its own.
Main memory banks were arranged in quadrants to be accessed at the same time, allowing programmers to scatter their data across memory to gain higher parallelism. The downside to this approach is that the cost of setting up the scatter/gather unit in the foreground processor was fairly high. Stride conflicts corresponding to the number of memory banks suffered a performance penalty (latency) as occasionally happened in power-of-2 FFT-based algorithms. As the Cray 2 had a much larger memory than Cray 1's or X-MPs, this problem was easily rectified by adding an extra unused element to an array to spread the work out.
Packed circuit boards and new design ideas
Cray-2 models soon settled on a design using large circuit boards packed with ICs. This made them extremely difficult to solder together, and the density was still not enough to reach their performance goals. Teams worked on the design for about two years before even Cray himself "gave up" and decided it would be best if they simply canceled the project and fired everyone working on it. Les Davis, Cray's former design collaborator who had remained at Cray headquarters, decided it should be continued at low priority. After some minor personnel movements the team continued on much as before.
Eureka (word)
"Eureka" is an interjection used to celebrate a discovery, a transliteration of a word attributed to Archimedes.-Etymology:The word comes from ancient Greek εὕρηκα heúrēka "I have found ", which is the 1st person singular perfect indicative active of the verb heuriskō "I find"...
" moment. He called the main engineers together for a meeting and presented a new solution to the problem. Instead of making one larger circuit board, each "card" would instead consist of a 3-D stack of eight, connected together in the middle of the boards using pins sticking up from the surface (known as "pogos" or "z-pins"). The cards were packed right on top of each other, so the resulting stack was only about 3 inches high. With this sort of density there was no way any conventional air-cooled system would work; there was too little room for air to flow between the ICs. Instead the system would be immersed in a tank of a new inert liquid from 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
, Fluorinert
Fluorinert
Fluorinert is the trademarked brand name for the line of electronics coolant liquids sold commercially by 3M. It is an electrically insulating, stable fluorocarbon-based fluid which is used in various cooling applications. It is mainly used for cooling electronics...
. The cooling liquid was forced sideways through the modules under pressure, and the flow rate was roughly one inch per second. The heated liquid was cooled using chilled water heat exchangers and returned to the main tank. Work on the new design started in earnest in 1982, several years after the original start date.
While this was going on the Cray X-MP
Cray X-MP
The Cray X-MP was a supercomputer designed, built and sold by Cray Research. It was announced in 1982 as the "cleaned up" successor to the 1975 Cray-1, and was the world's fastest computer from 1983 to 1985...
was being developed under the direction of Steve Chen at Cray headquarters, and looked like it would give the Cray-2 a serious run for its money. In order to address this internal threat, as well as a series of newer Japanese Cray-1-like machines, the Cray-2 memory system was dramatically improved, both in size as well as the number of "pipes" into the processors. When the machine was eventually delivered in 1985 the delays had been so long that much of its performance benefits were due to the faster memory. Purchasing the machine really made sense only for users with huge data sets to process.
The first Cray-2 delivered possessed more physical memory (256 MWord) than all previously delivered Cray machines combined. Simulation moved from a 2-D realm or coarse 3-D to a finer 3-D realm because computation did not have to rely on slow virtual memory.
Uses and successors
The Cray-2 was predominantly developed for the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Departments of Defense
United States Department of Defense
The United States Department of Defense is the U.S...
and Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
. Uses tended to be for nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
s research or oceanographic (sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
) development. However, the Cray-2 also found its way into civil agencies (such as NASA Ames Research Center
NASA Ames Research Center
The Ames Research Center , is one of the United States of America's National Aeronautics and Space Administration 10 major field centers.The centre is located in Moffett Field in California's Silicon Valley, near the high-tech companies, entrepreneurial ventures, universities, and other...
), universities, and corporations worldwide.
The Cray-2 would have been superseded by the Cray-3
Cray-3
The Cray-3 was a vector supercomputer intended to be Cray Research's successor to the Cray-2. The system was to be the first major application of gallium arsenide semiconductors in computing. The project was not considered a success, and the parent company in Minneapolis decided to end work on the...
, but due to development problems only a single Cray-3 was built and it was never paid for. The spiritual descendant of the Cray-2 is the Cray X1
Cray X1
The Cray X1 is a non-uniform memory access, vector processor supercomputer manufactured and sold by Cray Inc. since 2003. The X1 is often described as the unification of the Cray T90, Cray SV1, and Cray T3E architectures into a single machine...
, offered by Cray
Cray
Cray Inc. is an American supercomputer manufacturer based in Seattle, Washington. The company's predecessor, Cray Research, Inc. , was founded in 1972 by computer designer Seymour Cray. Seymour Cray went on to form the spin-off Cray Computer Corporation , in 1989, which went bankrupt in 1995,...
.
History
Due to the use of liquid cooling, the Cray-2 was given the nickname "Bubbles", and common jokes around the computer made reference to this unique system. Gags included "No Fishing" signs, cardboard depictions of the Loch Ness MonsterLoch Ness Monster
The Loch Ness Monster is a cryptid that is reputed to inhabit Loch Ness in the Scottish Highlands. It is similar to other supposed lake monsters in Scotland and elsewhere, though its description varies from one account to the next....
rising out of the heat exchanger tank, plastic fish inside the exchanger, etc. The power of the Cray-2 was 150 - 200 kW. Each vertical stack of logic modules sat above a stack of power modules which powered 5 volt bus bars, each of which delivered about 2200 amps. The Cray-2 was powered by two motor-generators, which took in 480 V three-phase
Three-phase electric power
Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by grids worldwide to transfer power. It is also used to power large motors and other heavy loads...
.