This book has evolved primarily from lecture notes for data
communications courses taught at Georgia State University since 1969.
Additional material was derived from seminar presentations that were
made during this period as well as from consulting work. Teaching data
communications in the College of Business Administration influenced the
point of view of this material, giving it a semitechnical orientation.
This point of view has been extended to the prepara- tion of this book.
Only those technical details were included which, it was felt, would
lead the student to a better understanding of the subject. References
are provided for those who desire further information in particular
areas. The reader for whom this book is intended is the nontechnical
person who has some knowledge of computer technology and who wishes to
extend that knowledge to the field of data communications. The two key
points stressed in this book are terminology and concepts. The
objectives of this book are to enable the student: 1. To read articles
in the field of data communications with an understand- ing of their
content. 2. To be able to engage in knowledgeable discussions with
communica- tions engineers on the subject of data communications. 3. To
design and implement the hardware aspects of applications using data
communications. The software that would be involved is beyond the scope
of this book except where protocols are considered. v vi Preface 4. To
effectively evaluate proposals for the implementation of data com-
munications systems.