Supercomputing in Japan
The K computer's performance is impressive, according to professor Jack Dongarra who maintains the TOP500 list of supercomputers, and it surpasses its next 5 competitors combined. The K computer costs US$10 million a year to operate.
Japan's entry into supercomputing started in the 1980s, and among others, the SX-3 supercomputer family was developed by NEC Corporation and announced in April 1989. The SX-3/44R became the fastest supercomputer in the world in 1990. Fujitsu's Numerical Wind Tunnel supercomputer gained the top spot in 1993.
The K computer's placement on the top spot is seven years after Japan held the title in 2004. The Earth Simulator supercomputer built by NEC at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) was the fastest in the world at that time with a peak of 131 TFlops, using proprietary vector processing chips. The K computer, on the other hand, uses over 60,000 commercial scalar SPARC64 VIIIfx processors housed in over 600 cabinets. The fact that K computer is over 60 times faster than the Earth Simulator, and that the Earth Simulator ranks as the 68th system in the world 7 years after holding the top spot demonstrates both the rapid increase in top performance in Japan and the widespread growth of supercomputing technology worldwide.
The GSIC Center at the Tokyo Institute of Technology houses the Tsubame 2.0 supercomputer, which has a peak of 2,288 Tflops and in June 2011 ranked 5th in the world. It was developed at the Tokyo Institute of Technology in collaboration with NEC and HP, and has 1,400 nodes using both HP Proliant and NVIDIA Tesla processors.
The RIKEN MDGRAPE-3 for molecular dynamics simulations of proteins is a special purpose petascale supercomputer at the Advanced Center for Computing and Communication, RIKEN in Wako, Saitama, just outside Tokyo. It uses over 4,800 custom MDGRAPE-3 chips, as well as Intel Xeon processors. However, given that it is a special purpose computer, it can not appear on the TOP500 list which requires Linpack benchmarking.
Historically, the Gravity Pipe (GRAPE) system for astrophysics at the University of Tokyo was distinguished not by its top speed of 64 Tflops, but by its cost and energy efficiency, having won the Gordon Bell Prize in 1999, at about $7 per megaflops, using special purpose processing elements. 
DEGIMA is a highly cost and energy-efficient computer cluster at the Nagasaki Advanced Computing Center, Nagasaki University. It is used for hierarchical N-body simulations and has a peak performance of 111 TFLOPS with an energy efficiency of 1376 MFLOPS/watt. The overall cost of the hardware was approximately US$500,000.
The Computational Simulation Centre, International Fusion Energy Research Centre of the ITER Broader Approach/Japan Atomic Energy Agency operates a 1.52-PFLOPS supercomputer (currently operating at 442 TFLOPS) in Rokkasho, Aomori. The system, called Helios (aka Roku-chan), consists of 4410 bullx B510 compute blades, and is used for fusion simulation projects.
The University of Tokyo's Information Technology Center in Kashiwa, Chiba began operations of a 1.13-PFLOPS supercomputer system (Oakleaf-FX) in April 2012. The system uses a Fujitsu PRIMEHPC FX10 configuration, a commercial version of the K supercomputer, composed of 4,800 computing nodes of SPARC64 IXfx processors connected via 6-dimensional mesh/torus interconnect.
In June 2012, the Numerical Prediction Division, Forecast Department of the Japan Meteorological Agency deployed an 847-TFLOPS Hitachi SR16000/M1 supercomputer, which is based on IBM Power 775, at the Office of Computer Systems Operations and the Meteorological Satellite Center in Kiyose, Tokyo. The system consists of two 432-logical node clusters of SR16000/M1. Each node consists of 4 IBM POWER7 (3.83GHz) processors and 128GB memory. The system is used to run a high resolution local forecast model (2 km horizontally and 60 layers vertically, up to 9-hour forecast) every hour.
Starting in 2003, Japan used grid computing in the National Research Grid Initiative (NAREGI) project to develop high-performance, scalable grids over very high-speed networks as a future computational infrastructure for scientific and engineering research.
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