Today's silicon-based microprocessors are manufactured under the strictest of conditions. Massive filters clean the air of dust and moisture, workers don spacesuit-like gear and the resulting systems are micro-tested for the smallest imperfection. But at a handful of labs across the country, researchers are building what they hope will be some of tomorrow's computers in environments that are far from sterile-beakers, test tubes and petri dishes full of bacteria. Simply put, these scientists seek to create cells that can compute, endowed with "intelligent" genes that can add numbers, store the results in some kind of memory bank, keep time and perhaps one day even execute simple programs.

All of these operations sound like what today's computers do. Yet these biological systems could open up a whole different realm of computing. "It is a mistake to envision the kind of computation that we are envisioning for living cells as being a replacement for the kinds of computers that we have now," says Tom Knight, a researcher at the MIT Artificial Intelligence Laboratory and one of the leaders in the biocomputing movement. Knight says these new computers "will be a way of bridging the gap to the chemical world. Think of it more as a process-control computer. The computer that is running a chemical factory. The computer that makes your beer for you."