CDC 8600
Encyclopedia
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 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-100
series instead.
s, resistor
s, etc.) on circuit boards. Several boards would be use to make a discrete logic element of the machine, known as a "module
." Overall machine "cycle speed" is strongly related to the signal path – the length of the wiring – requiring 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 in order to increase functionality. By the late 1960s individual components had stopped getting much smaller, and although integrated circuits addressed the size issue, their simple MOSFET
-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. In theory, this could slow the machine down due to signalling delays. 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 Amana
, 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 freon 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-2
.
The components themselves were likewise improved over previous designs. The main CPU
circuits moved to ECL
-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, 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 SIMD
, 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 ASCII
-based processing, and therefore used a 64-bit
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/O
, largely unchanged.
, 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 wage
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 Norris
(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 IV
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 STAR
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-1
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.
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...
's 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...
designs while working for the Control Data Corporation
Control Data Corporation
Control 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 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...
and 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...
, 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-100
CDC STAR-100
The STAR-100 was a vector supercomputer designed, manufactured, and marketed by Control Data Corporation . It was one of the first machines to use a vector processor to improve performance on appropriate scientific applications....
series instead.
Design
In the 1960s computer design was based on mounting electronic components (transistorTransistor
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...
s, resistor
Resistor
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...
s, etc.) on circuit boards. Several boards would be use to make a discrete logic element of the machine, known as a "module
Computer module
A computer module is a selection of independent electronic circuits packaged onto a circuit board to provide a basic function within a computer. An example might be an inverter or flip-flop, which would require two or more transistors and a small number of additional supporting devices...
." Overall machine "cycle speed" is strongly related to the signal path – the length of the wiring – requiring 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 in order to increase functionality. By the late 1960s individual components had stopped getting much smaller, and although integrated circuits addressed the size issue, their 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 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. In theory, this could slow the machine down due to signalling delays. 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 Amana
Amana Corporation
The Amana Corporation is an American brand of household appliances. It was founded in 1934 by George Foerstner as The Electrical Equipment Co. in Middle Amana, Iowa to manufacture commercial walk-in coolers. The business was later owned by the Amana Society and became known as Amana Refrigeration,...
, 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 freon 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-2
Cray-2
The Cray-2 was a four-processor ECL vector supercomputer made by Cray Research starting in 1985. It was the fastest machine in the world when it was released, replacing the Cray Research X-MP designed by Steve Chen in that spot...
.
The components themselves were likewise improved over previous designs. The main CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
circuits moved to ECL
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....
-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, 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 SIMD
SIMD
Single instruction, multiple data , is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data simultaneously...
, 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 ASCII
ASCII
The 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-bit
64-bit
64-bit is a word size that defines certain classes of computer architecture, buses, memory and CPUs, and by extension the software that runs on them. 64-bit CPUs have existed in supercomputers since the 1970s and in RISC-based workstations and servers since the early 1990s...
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/O
I/O
I/O may refer to:* Input/output, a system of communication for information processing systems* 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 IBMIBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
, 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 wage
Minimum wage
A minimum wage is the lowest hourly, daily or monthly remuneration that employers may legally pay to workers. Equivalently, it is the lowest wage at which workers may sell their labour. Although minimum wage laws are in effect in a great many jurisdictions, there are differences of opinion about...
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 Norris
William Norris
William 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 IV
ILLIAC IV
The ILLIAC IV was one of the most infamous supercomputers ever built. One of 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...
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 STAR
CDC STAR-100
The STAR-100 was a vector supercomputer designed, manufactured, and marketed by Control Data Corporation . It was one of the first machines to use a vector processor to improve performance on appropriate scientific applications....
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-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...
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.
External links
- Neil R. Lincoln with 18 Control Data Corporation (CDC) engineers on computer architecture and design, Charles Babbage InstituteCharles Babbage InstituteThe Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....
, University of Minnesota. Engineers include Robert Moe, Wayne Specker, Dennis Grinna, Tom Rowan, Maurice Hutson, Curt Alexander, Don Pagelkopf, Maris Bergmanis, Dolan Toth, Chuck Hawley, Larry Krueger, Mike Pavlov, Dave Resnick, Howard Krohn, Bill Bhend, Kent Steiner, Raymon Kort, and Neil R. Lincoln. Discussion topics include CDC 1604CDC 1604The CDC 1604 was a 48-bit computer designed and manufactured by Seymour Cray and his team at the Control Data Corporation. The 1604 is known as the first commercially successful transistorized computer. Legend has it that the 1604 designation was chosen by adding CDC's first street address to...
, CDC 6600CDC 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...
, CDC 7600CDC 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 ran at 36.4 MHz and had a 65 Kword primary memory using core and variable-size secondary memory...
, CDC 8600, CDC STAR-100CDC STAR-100The STAR-100 was a vector supercomputer designed, manufactured, and marketed by Control Data Corporation . It was one of the first machines to use a vector processor to improve performance on appropriate scientific applications....
and Seymour CraySeymour CraySeymour 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...
.