The low cost of microprocessor and microcomputer technology is such that microcomputers are finding wide application in many of the geological sciences and engineering. This paper, therefore, is aimed at providing an introduction to, and brief review of, the microcomputer field. The basic terms in use are explained and the main microprocessor chips and microcomputer systems surveyed. The distinction is made between systems which use embedded microprocessors and systems which provide enhanced capabilities by software development and interfacing to a personal microcomputer. A number of applications of microcomputers in engineering geology and engineering geophysics are used to illustrate the impact and scope of the new technology.