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Hot trend in computing: Chips that sometimes get it wrong [Houston Chronicle](Houston Chronicle (TX) Via Acquire Media NewsEdge) May 18--At first blush it appears a daft notion: increasing the speed and efficiency of computer processors at the cost of a few computational errors. Nevertheless, as a Houston computer scientist has developed his ideas over nearly a decade, he has found increasing acclaim for his "inexact" computer chips. This week, at a major computing conference in Italy, Rice University's Krishna Palem unveiled his newest chips that trade a bit of accuracy for better efficiency. "When we first started working on this there was a large part of the world that was skeptical about what we were doing," said Palem, who holds a joint appointment at Singapore's Nanyang Technological University. "But I can very confidently say that we are past that now." That does not seem to be an idle boast. After Palem and his colleagues demonstrated their prototype chips at the ACM International Conference on Computing Frontiers in Cagliari, Italy, this week it earned "best paper" honors from attendees. "This work opens the door to interesting energy-efficiency opportunities of using inexact hardware together with traditional processing elements," said Paolo Faraboschi, the program co-chair of the conference and a distinguished technologist at Hewlett-Packard Laboratories. Palem's approach, known as probabilistic computing, involves taking existing computer chips and modifying them. Within a basic computer chip there are "blocks" of hardware that do computational work. But some of these blocks do more, or more important work than other blocks, Palem said. For example, the block that calculates a higher-order number in a bank balance, the "5" in $5,300.61, is more critical than the block that calculates the 1 cent at the end. A snip boosts speed By studying chips Palem's research group, which also included members from Switzerland's Center for Electronics and Microtechnology and the University of California, Berkeley, identified the blocks that did the most important work. They then selectively snipped out the blocks that did less work, or the least important computations. "When we pruned the chips this way we dramatically increased their efficiency and speed," Palem said. The group's testing showed that pruning could cut energy demands 3.5 times with chips that deviated from the correct value by an average of 0.25 percent. Factoring in size and speed, the pruned chips were 7.5 times more efficient than regular computer chips. But isn't the whole point of computers to deliver the right calculation, every time? For some applications such as bank balances, of course, absolute accuracy is critical, Palem said. Inexact chips However there are a large number of applications where minor errors go unnoticed by consumers: audio, video, large-scale simulations, search engine results and more. The chips are already being incorporated into some hardware. Inexact chips are a key component of the low-cost I-slate educational tablet designed for Indian classrooms with no electricity and too few teachers. Officials in India's Mahabubnagar District announced plans in March to adopt 50,000 I-slates in middle and high school classrooms over the next three years. And Palem says that's just the beginning. It could be used in a wide variety of devices, from mobile phones to hearing aids. "This idea has really spread in recent years," he said. "I think this is the beginning of a big expansion." [email protected] ___ (c)2012 the Houston Chronicle Visit the Houston Chronicle at www.chron.com Distributed by MCT Information Services |