The development of the microprocessor and the subsequent IBM personal computer led to a growth in the processing of the data from sensors during the 1980s. Digital-to-analogue converter before analogue-to-digital converter (ADC) since some ADCs use a digital-to-analogue converter as part of their structure. Many sensors are sold which have a microprocessor contained within the sensor unit and are described as smart sensors. The sensor itself is under microprocessor control, enabling the excitation levels to be adjusted so that switching between ranges can be done automatically. There are many situations that require the processing and analysis of the information from several sensors. The chapter describes some aspects of artificial intelligence appropriate to instrumentation applications. The fundamental building block is a mathematical model of the biological neurone. These artificial neurones are grouped into some structure that is then trained using sets of data.