Our goal is to develop silicon learning systems. One impediment to achieving this goal has been the lack of a simple circuit element combining nonvolatile
analog memory storage with locally computed memory updates. Existing circuits [63, 132] typically are large and complex; the nonvolatile floating-gate devices,
such as EEPROM transistors. typically are optimized for binary-valued storage [17], and do not compute their own memory updates. Although floating-gate
transistors can provide nonvolatile analog storage [1, 15], because writing the memory entails the difficult process of moving electrons through Si0_2, these devices have not seen wide use as memory elements in silicon learning systems
