Covers technical developments and results of the Midwest archaeological Center's (National Park Service) 1977 season of magnetic surveying of Great Plains sites; there were 16 sites extending from North Dakota to Arizona and covering about 5.6 hectares. The survey data collecting was automated by linking a microcomputer directly to two proton magnetometers. The complete field system consists of two magnetometers with BCD output, microcomputer, keyboard, TV tube and audio-cassette recorder. The data are viewed on the tube, printed out and transferred to the central computer by means of a cassette player, modem, and telephone line. The system and its various components are discussed. The field operation is described including modes of data collection and in-field data processing.