By Ina Fried (CNET News)
While Windows is ubiquitous on the desktop and well represented in the server racks, until recently it has been nearly absent from the world's largest supercomputers.
Starting several years ago, though, Microsoft made a concerted effort at this part of the market, creating a separate version of Windows solely for computing clusters.
The first big fruits of that effort were evidenced in this year's top 500 list of the world's biggest supercomputers. Five of those on the list were Windows clusters, including one at the National Center for Supercomputing Applications that ranked No. 23.

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