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World’s Fastest One-Chip CPU

There is no fixed definition of what qualifies as a “supercomputer.” Essentially, the fastest computers in any given era get the title. NEC first became involved in the business of building supercomputers in the early 1980s. At the time, the company provided large, general-purpose computers in quantity to organizations such as universities and research institutions, but when such users increasingly said they wanted to use supercomputers, the company went to work. NEC has now shipped over 400 of its mainstay SX series line of supercomputers. Nearly half of those were shipped overseas, mainly to Europe. There are only five or six supercomputer makers, all in Japan or the US, and NEC has a track record that puts it in the top class. Despite NEC’s strong position in the industry, it was by no means an easy matter to develop a supercomputer with such advanced specifications. We discussed the development challenges with the first name in Japanese supercomputer development, Tadashi Watanabe, Vice President of NEC’s High Performance Computing: “The CPUs in most supercomputers have a multi-chip architecture, but for the Earth Simulator, we developed a one-chip vector processor. The point of this was to reduce the overall size of the system, and this was the most difficult stage of the development process. Creating a one-chip architecture comes at a cost. But if we were to lose total capabilities or functions as a result, it would be counterproductive. We had to figure out a way to make up for every bit of speed or functionality we had to sacrifice to create a one-chip design with speed improvements elsewhere. The design stage lasted three to four years and was much like solving a giant jigsaw puzzle.” The one-chip vector processor NEC developed for the Earth Simulator is 2 cm square. It is almost completely packed with 0.15-micron copper wiring, which is of a thickness roughly 1/1,500th that of a human hair. Imagine the playing surface of a baseball field intricately and accurately packed with 1.5 mm wiring with minimal space between wires. It is also unusual to use copper to wire a semiconductor. Aluminum is typically used because it is easier to process and prepare than copper, and is highly resistant to thermal expansion and changes in temperature and humidity. Chemically, aluminum is highly compatible with the silicon used as the chip substrate. Copper, however, is a better electrical conductor, which makes chips that use it that much faster. The developers of the Earth Simulator, tasked with achieving extremely high performance, chose to work to overcome the drawbacks of copper while making the most of its benefits. As a result of such effort and ingenuity, the team developed a one-chip vector processor for the Earth Simulator that achieved a speed of 8 gigaflops (8 billion floating point operations per second), a world record. In addition to packing this processor, the Earth Simulator is also full of the newest, leading-edge technology in other areas. For example, it is connected by a data-cable network capable of transmitting an amount of data equivalent to 10 trillion characters of text per second. Looking back on over 20 years in supercomputer development, Watanabe is deeply moved. "Supercomputer technology continues to advance much more quickly than we had imagined it would. That’s why as developers, we've always got to keep raising the bar to the next level. This is by no means easy, but for an engineer, working to develop world-leading technology is extremely rewarding."

A one-chip vector processor, which integrates several CPUs that were previously on discrete chips. One vector processor can do up to eight gigaflops, the world’s highest-class performance.