Interrupts and Polling

Abstract

Many microcomputers have a large number of input devices connected to them. Since the CPU can only receive data from one input device at a time, the programmer may be in a dilemma as to which device to take data from at a particular instant in time. Take, for example, a steam boiler control system in which the steam pressure is monitored by a sensor. If the pressure suddenly rises to an unacceptably high value, the CPU must take rapid action to reduce the pressure. However, since the CPU may have to read data from a very large number of sensors, the question arises as to how the computer can be organised to detect quickly which sensor indicates a dangerous condition.