The course contained in this book was written for training data processing machine operators; it is intended to prepare adults to qualify for an entry-level job. It is not aimed at developing high proficiency on any one machine, but rather at introducing the student to a variety of equipment, and developing an understanding of how the data flow through a unit-record system. The topics discusssed include: the basic functions of data processing; the unit record principle and the punched card; the card punch and verifier; the interpreter; the sorter; the reproducer; the collator; the accounting machine or tabulator; the calculating punch; documentation; and integrated applications. A bibliography and introductory projects are included. This course is related to two others published by the New York State Education Department: "Keypunch Operation" and "Introduction to Automatic Data Processing." (PT)