HP RESEARCHERS have developed a working unit of a once-theoretical memory circuit called a memristor, which may someday re place RAM and make PCs smarter. Memristor technology could enable PCs to make decisions by understanding patterns of collected data, much as ahuman brain collects and understands data on a series of events.For example, a memristor could adjust a microwave’s heating time for a potato based on whether the oven overcooked a potato the last time, says HP senior fellow Stanley Williams. Memristors could reach the commercial semiconductor market in five years, he says.A memristor circuit uses lower voltage and turns on faster than memory types such as DRAM and flash. Denser cells allow memristor circuits to store more data than flash memory, too. The memristor is the fourth basic circuitry element, joining three, the resistor, the capacitor, and the inductor. That science has known about for 150 years,Williams says.