A constantly expanding, vast network of telecommunication links spans the industrialized countries of the world, carrying telephone, telegraph, and television signals, news photographs, and radio programs. The field of data transmission through these links is covered in this book, which first offers a brief rationale and discussion of various types of terminals. Other sections deal with categories of data transmission systems, communication channel capacity, categories of communication lines, modem and data sets, characters and codes, modes of transmission, line errors, man-computer dialog, multiplexing, network structure, the transmission control unit, terminal consideration, software, the flow of data, and design techniques. The appendixes give more comprehensive summaries and checklists for use in the design and selection of teleprocessing equipment. Also included are a list of references, class questions, and a glossary. (RH)