The
CDC 8600 was the last of
Seymour CraySeymour Roger Cray was a U.S. electrical engineer and supercomputer architect who designed a series of computers that were the fastest in the world for decades, and founded the company Cray Research which would build many of these machines...
's
supercomputerA supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation , and led the market into the 1970s until Cray left to form...
designs while working for the
Control Data CorporationControl Data Corporation was a supercomputer firm. For most of the 1960s, it built the fastest computers in the world by far, only losing that crown in the 1970s after Seymour Cray left the company to found Cray Research, Inc....
. The "natural successor" to the
CDC 6600The 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...
and
CDC 7600The 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 had a 27.5 ns clock cycle and a 65 Kword primary memory using core and variable-size secondary memory . It was generally about ten times as...
, the 8600 was intended to be about 10 times as fast as the 7600, already the fastest computer on the market.
Development started in 1968, shortly after the release of the 7600, but the project soon started to bog down. By 1971 CDC was having cash flow problems and the design was still not coming together, prompting Cray to leave the company in 1972.
The
CDC 8600 was the last of
Seymour CraySeymour Roger Cray was a U.S. electrical engineer and supercomputer architect who designed a series of computers that were the fastest in the world for decades, and founded the company Cray Research which would build many of these machines...
's
supercomputerA supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation , and led the market into the 1970s until Cray left to form...
designs while working for the
Control Data CorporationControl Data Corporation was a supercomputer firm. For most of the 1960s, it built the fastest computers in the world by far, only losing that crown in the 1970s after Seymour Cray left the company to found Cray Research, Inc....
. The "natural successor" to the
CDC 6600The 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...
and
CDC 7600The 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 had a 27.5 ns clock cycle and a 65 Kword primary memory using core and variable-size secondary memory . It was generally about ten times as...
, the 8600 was intended to be about 10 times as fast as the 7600, already the fastest computer on the market.
Development started in 1968, shortly after the release of the 7600, but the project soon started to bog down. By 1971 CDC was having cash flow problems and the design was still not coming together, prompting Cray to leave the company in 1972. The 8600 design effort was eventually cancelled in 1974, and Control Data moved on to the
CDC STAR-100The STAR-100 was a supercomputer from Control Data Corporation , one of the first machines to use a vector processor for improved math performance....
series instead.
Design
In the 1960s computer design was based on mounting electronic components (
transistorA transistor is a semiconductor device commonly used to amplify or switch electronic signals. A transistor is made of a solid piece 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...
s,
resistor|- align = "center"||width = "25"|| |- align = "center"||| Potentiometer|- align = "center"| || |- align = "top"| Resistor|| Variable
resistor|- align = "center"||width = "25"|| |- align = "center"||| Potentiometer|- align = "center"...
s, etc.) on circuit boards. Several boards would be use to make a discrete logic element of the machine, known as a "module". As computer power increased the complexity of the modules did too, and even a single faulty part or solder joint would render the entire module inoperative. Cray was well known in the industry for making seemingly impossibly complex modules work.
Overall machine "cycle speed" is strongly related to the signal path – the length of the wiring – forcing high speed computers to make their modules as small as possible. This was at odds with the need to make the modules themselves more complex to increase computing power. By the late 1960s individual components had stopped getting much smaller, and although integrated circuits addressed the size issue, their simple
MOSFETThe metal–oxide–semiconductor field-effect transistor is a device used to amplify or switch electronic signals. The basic principle of the device was first proposed by Julius Edgar Lilienfeld in 1925...
-based technology didn't have the performance needed for high-speed applications. So in order to increase the complexity of the machines, the modules would have to grow.
Cray aimed to solve these contradictory problems by doing both; making each module larger and crammed with many more components, while at the same time making the computer as a whole smaller by packing the modules closer together inside the machine. In the case of the 8600, this led to modules containing eight four-layer circuit boards about 8" by 6", resulting in a stack the size of a large textbook and using up about 3 kilowatts of power.
Cooling the modules proved to be a major problem. Cray's refrigeration engineer, Dean Roush, formerly of
AmanaThe Amana Corporation was founded by George Foerstner as Amana Refrigeration in 1934 in Middle Amana, Iowa to manufacture commercial walk-in coolers. The business was owned by the Amana Society. In 1947, it manufactured the first upright freezer for the home, and in 1949 added a side-by-side...
, placed a sheet of copper inside each of the circuit boards, removing the heat to a copper block on one end where it was cooled by a
freonFreon is DuPont's trade name for chlorofluorocarbon and hydrochlorofluorocarbons. In other countries the same family of chemical compounds are called Isceon, Ledon, Frigen, Kaltron, Flugene, Forane, Fridohna, Frigedohn, Algofrene, Asahiflon, Daiflon, Flon, Genetron, Kaiser, Isotron, Racon, Ucon,...
system. This further increased the weight and complexity of the modules, to the point where each one weighed about 15 pounds. The modules were then packed into a mainframe chassis that was comparatively tiny, a 16-sided cylinder about one meter across and high, sitting on top of a ring of power supplies. The external cooling system was considerably larger than the machine itself. Perhaps unsurprisingly, the 8600 bears a strong resemblance to the later
Cray-2The Cray-2 was a vector supercomputer made by Cray Research starting in 1985. It was the fastest machine in the world when it was released, replacing Cray's own X-MP in that spot...
.
The components themselves were likewise improved over previous designs. The main
CPUThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
circuits moved to
ECLIn electronics, emitter-coupled logic, or ECL, is a logic family in which current is steered through bipolar transistors to prevent saturation...
-based logic, allowing the clock speed to be increased to 8 ns (125 MHz) from the 7600's 27.5 ns – an increase of about four times. Main memory was also moved to an ECL implementation and the machine was equipped with a whopping 256k-words (2 megabytes) standard. The memory was spread across 64 banks storing one bit of a word each, thereby allowing fast access at about 8 ns/word even though the cycle time of any one bank was about 250 ns. A high-speed core memory with a 20 ns access (overall) was also designed as a backup to the semiconductor version.
Cray decided that the 8600 would include four complete CPUs sharing the main memory. In order to improve overall throughput, the machine could be operated in a special mode in which a single instruction was sent to all four processors with different data. This technique, today known as
SIMDIn computing, SIMD is a technique employed to achieve data level parallelism.- History :...
, reduced the total number of memory accesses because the instruction was only read once, instead of four times. Each processor was about 2.5 times as fast as a 7600, so with all four running the machine as a whole would be about 10 times as fast, at about 100 MFLOPS.
The 8600 was the first CDC design to move to
ASCIIThe American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
-based processing, and therefore used a
64-bit64-bit CPUs have existed in supercomputers since the 1960s and in RISC-based workstations and servers since the early 1990s. In 2003 they were introduced to the mainstream personal computer arena, in the form of the x86-64 and 64-bit PowerPC processor architectures.Without further qualification, a...
word (eight bytes) instead of the earlier 60-bit word (ten 6-bit characters) used on the 6600 and 7600. As in prior designs, instructions were "stuffed" into words, with each instruction taking up either 16 or 32 bits (up from 15/30). The 8600 no longer used the A or B registers as in previous designs, and included a set of 16 general-purpose X registers instead. A 6600/7600 Peripheral Processor system was used for
I/OI/O may refer to:* Input/output, a system of communication for information processing systems* The input-output model, an economic model of flow prediction between sectors...
, largely unchanged.
Company problems
In 1971 Control Data was undergoing a "belt tightening" due to the cost of an ongoing lawsuit against
IBMInternational Business Machines Corporation, abbreviated IBM, is a multinational computer technology and IT consulting corporation headquartered in Armonk, Town of North Castle, New York, United States. The company is one of the few information technology companies with a continuous history dating...
, and all divisions were asked to reduce their payroll by 10%. Cray begged to be exempted in order to get the 8600 shipping, and when this request was refused he instead had his own pay cut to
minimum wageA minimum wage is the lowest hourly, daily or monthly wage that employers may legally pay to employees or workers. Equivalently, it is the lowest wage at which workers may sell their labor. Although minimum wage laws are in effect in a great many jurisdictions, there are differences of opinion...
to solve the problem.
By 1972 it appeared that even Cray's legendary module design abilities were failing him in the case of the 8600. Reliability was so poor that it was appeared impossible to get a whole machine working. This was not the first time this had happened, on the 6600 project Cray had to start over from scratch, and the 7600 was in production for some time before it started working reliably. In this case Cray decided the current design was a dead-end, and told
William NorrisWilliam Charles Norris was the pioneering CEO of Control Data Corporation, at one time one of the most powerful and respected computer companies in the world...
(CDC's CEO) that the only way forward was to redesign the machine from scratch. The finances of the company were dangerous, and Norris decided that he couldn't take the risk; Cray would have to continue with the current design.
In 1972 Cray decided that he couldn't work under such conditions, and left CDC to form Cray Research. For his new work he abandoned the multiprocessor concept, concerned that software of the era would be unable to take full advantage of the CPUs. He may have come to this conclusion after the
ILLIAC IVThe ILLIAC IV was one of the most infamous supercomputers ever. Last in a series of research machines, the ILLIACs from the University of Illinois, the ILLIAC IV design featured fairly high parallelism with up to 256 processors, used to allow the machine to work on large data sets in what would...
finally entered operation at about the same time, and proved to have disappointing performance.
Team members convinced Norris that the 8600 could be completed even without Cray, and work continued at the Chippewa Lab. By 1974 the machine still didn't work correctly. Jim Thornton's competing
STARThe STAR-100 was a supercomputer from Control Data Corporation , one of the first machines to use a vector processor for improved math performance....
design had reached production quality at this point, and the 8600 project was then cancelled. In service STAR proved to have poor real-world performance, and when the
Cray-1The Cray-1 was a supercomputer designed by a team including Seymour Cray for 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.-History:In the years 1968 to...
entered the market in 1976, CDC was quickly pushed from the supercomputer market. An effort was made to re-enter the market in the 1980s with the ETA-10, but this ended poorly.