Connection Machine

Thinking Machines CM-2 at the Computer History Museum in Mountain View, California. One of the face plates has been partially removed to show the circuit boards inside.

The Connection Machines were a series of supercomputers that grew out of Danny Hillis's doctoral research at MIT in the early 1980s on alternatives to the traditional von Neumann architecture of computation. The Connection Machines (CMs), beginning with CM-1, were originally intended for applications in artificial intelligence and symbolic processing, but later versions found greater success in the field of computational science.

Origin of idea

Danny Hillis and Sheryl Handler founded Thinking Machines (TMC) in Waltham, Massachusetts in 1983, later moving it to Cambridge, MA. At TMC, Hillis assembled a team to develop what would become the CM-1 Connection Machine, a design for a "massively parallel" hypercubic arrangement of thousands of microprocessors, springing from this PhD thesis work at MIT in Electrical Engineering and Computer Science (1985). The dissertation won the ACM Distinguished Dissertation prize in 1985, and was presented as a monograph that overviewed the philosophy, architecture, and software for the first Connection Machine, including information on its data routing between CPU nodes, its memory handling, and the Lisp programming language applied in the parallel machine.

CM designs

Each CM-1 microprocessor had its own 4 kbits of RAM, and the hypercubic array of them was designed to performed the same operation on multiple data points simultaneously, i.e., to execute tasks in single instruction, multiple data (SIMD) fashion. The CM-1, depending on the configuration, had as many as 65,536 individual processors, each extremely simple, processing one bit at a time. CM-1 and its successor CM-2 took the form of a cube 1.5 meters on a side, divided equally into eight smaller cubes. Each sub-cube contained 16 printed circuit boards and a main processor called a sequencer. Each printed circuit board contained 32 chips. Each chip contained a communication channel called a router, 16 processors, 16 RAMs. The CM-1 as a whole had a hypercubic routing network, a main RAM, and an input/output processor. It was connected to a switching device called a nexus.

In order to improve its commercial viability, TMC launched the CM-2 in 1987, adding Weitek 3132 floating-point numeric co-processors and more RAM to the system. 32 of the original one-bit processors shared each numeric processor. The CM-2 could be configured with up to 512 MB of RAM, and a RAID hard disk array, called a DataVault, of up to 25 GB. Two later variants of the CM-2 were also produced, the smaller CM-2a with either 4096 or 8192 single-bit processors, and the faster CM-200.

The light panels of FROSTBURG, a CM-5, on display at the National Cryptologic Museum. The panels were used to check the usage of the processing nodes, and to run diagnostics.

Due to its origins in AI research, the software for the CM-1/2/200 single-bit processor was influenced by the Lisp programming language and a version of Common Lisp, *Lisp (spoken: "Star-Lisp"), was implemented on the CM-1. Other early languages included Karl Sims' IK and Cliff Lasser's URDU. Much system utility software for the CM-1/2 was written in *Lisp. Many applications for the CM-2, however, were written in C*, a data-parallel superset of ANSI C.

With the CM-5, announced in 1991, TMC switched from the CM-2's hypercubic architecture of simple processors to an entirely new MIMD architecture based on a fat tree network of SPARC RISC processors. The later CM-5E replaced the SPARC processors with faster SuperSPARCs. The CM-5 was the second fastest system in the November 1993 TOP500 list, running 1024 cores with Rpeak of 131.0 GFlop/s.

Visual design

Connection Machines were noted for their (intentionally) striking visual design. The CM-1 and CM-2 design teams were led by Tamiko Thiel. The physical form of the CM-1, CM-2, and CM-200 chassis was a cube-of-cubes, referencing the machine's internal 12-dimensional hypercube network, with the red LEDs, by default indicating the processor status, visible through the doors of each cube.

By default, when a processor was executing an instruction, its LED was on. In a SIMD program, the goal is to have as many processors as possible working the program at the same time – indicated by having all LEDs being steady on. Those unfamiliar with the use of the LEDs wanted to see the LEDs blink – or even spell out messages to visitors. The result was that finished programs often had superfluous operations to blink the LEDs.

The CM-5, in plan view, had a "staircase"-like shape, and also had large panels of red blinking LEDs. Perhaps because of its industrial design, a CM-5 was featured in the movie Jurassic Park in the control room for the island (instead of a Cray X-MP supercomputer as in the novel). Prominent sculptor/architect Maya Lin contributed to the CM-5 design.

See also

• ICL DAP
• Goodyear MPP
• Parallel computing
• FROSTBURG — a CM-5 used by the NSA
• David E. Shaw's NON-VON machine, which preceded the Connection machine slightly.
• MasPar
• Brewster Kahle - Lead engineer on the Connection Machine projects.

Further reading

• Hillis, D. 1982 "New Computer Architectures and Their Relationship to Physics or Why CS is No Good", Int J. Theoretical Physics 21 (3/4) 255-262.
• Lewis W. Tucker, George G. Robertson, "Architecture and Applications of the Connection Machine," Computer, vol. 21, no. 8, pp. 26–38, August, 1988.
• Arthur Trew and Greg Wilson (eds.) (1991). Past, Present, Parallel: A Survey of Available Parallel Computing Systems. New York: Springer-Verlag. ISBN 0-387-19664-1
• Charles E. Leiserson, Zahi S. Abuhamdeh, David C. Douglas, Carl R. Feynman, Mahesh N. Ganmukhi, Jeffrey V. Hill, W. Daniel Hillis, Bradley C. Kuszmaul, Margaret A. St. Pierre, David S. Wells, Monica C. Wong, Shaw-Wen Yang, and Robert Zak. "The Network Architecture of the Connection Machine CM-5". Proceedings of the fourth annual ACM Symposium on Parallel Algorithms and Architectures. 1992.
• W. Daniel Hillis and Lewis W. Tucker. The CM-5 Connection Machine: A Scalable Supercomputer. In Communications of the ACM, Vol. 36, No. 11 (November 1993).

External links

• Gallery of CM-5 images
• CM-5 Manuals
• Tamiko Thiel on the visual design of the CM-1/2/200
• Feynman and the Connection Machine
• Liquid Selves, an animated short film rendered on a CM-2
• A preserved CM-2a at the Corestore Computer Museum

Records
Preceded by NEC SX-3/44 20.0 gigaflops	World's most powerful supercomputer Thinking Machines CM-5/1024 June 1993	Succeeded by Numerical Wind Tunnel 124.0 gigaflops