First published in 1981. This book has been written for those who want to comprehend how a large natural language-understanding program works. Thirty-five professionals in Cognitive Science, mostly psychologists by training, in a summer school were taught to grapple with the details of programming in Artificial Intelligence. As a part of the curriculum designed for this project the authors created what they called micro-programs. These micro-programs were an attempt to give students the flavor of using a large AI program without all the difficulty normally associated with learning a complex system written by another person. Using the authors' parser, ELI, or story understanding program, SAM, they also gave students the micro versions of these programs, which were very simple versions that operated in roughly the same way as their larger versions, but without all the frills. Students were asked to add pieces to the programs and otherwise modify them in order to learn how they worked.