ting. Embedded computers are already an integral part of modern life. They're increasingly becoming the brains behind the core mechanisms inside a variety of common products, including wireless devices, cars, automated elevators, climate control systems, traffic signals, and washing machines. "Some experts estimate that each individual in a developed nation may unknowingly use more than 100 embedded computers daily," says Sandeep Shukla, an assistant professor of electrical and computer engineering at Virginia Tech. Shukla recently received a $400,000 grant from the National Science Foundation to help solve the problem of transitioning businesses and people from a world of desktop and handheld computers to embedded devices. There are two performance factors critical to embedded computers: speed and quality of service. "If the power supplied by the battery is too low, the computer's performance is reduced," Shukla says. "The question is whether a PROJECT OXYGEN compromise between performance and power is reasonable for a particular device or application." Shukla wants to support the current and future uses of embedded com- puters by developing a power usage strategy that can guarantee maximum per- formance. This entails analyzing the complex probabilities of when computers will require power and how much power they will use. "It's similar to design- ing a network of traffic lights for a particular traffic pattern," he says. "The highway engineer has to study the probabilities of when and where traffic is the heaviest and then set up a network of lights that will allow a maximum flow of traffic." One possible usage strategy would be to place a mobile phone into "sleep" mode during times when the probability of usage is low. The design would keep the system in a "ready" mode when incoming and outgoing calls are expected and fast action is required. Such a strategy would reduce power use and increase the life of the battery while optimizing the cell phone's performance. Using a probability analysis modeling tool call