This is a book about the various types of devices that are currently available from different manufacturers/vendors for the data communications users. As stated by the author in his Preface, the operational characteristics and applications of these devices “are usually omitted from most books covering the data communications field.”

Indeed, textbooks on data communications tend to be written from the network provider’s perspective. More often than not, the object under discussion is a public network run by some operating company. Held’s book is distinct in the sense that it presents a user’s view. Held discusses what kinds of off-the-shelf components a user can readily employ in the design, modification, or optimization of a private network. In this respect, the book is a welcome new addition to the field.

The 1986 edition is a complete revision of [1], published in 1979. Even though it is a major rework, the types of devices described in the new version still reflect only those that were available a decade ago. With the proliferation of LANs, the general acceptance of X.25, and the emergence of ISDN, one would have thought that any recently published book on data communications would include at least some treatment of these topics. Yet, none of them are mentioned in the book.

The original 1979 edition evolved from a series of articles written by the same author for the Data Communications magazine. Rather than just a collection of disjoint articles, the author is successful in presenting a coherent picture on the huge array of devices available. Other than the introductory and concluding chapters, all the other chapters are organized so that each covers a group of devices based upon a common function. A listing of the chapter headings will illustrate this and also show the contents of the book:

• (1) Fundamental Concepts.

• (2) Data Transmission Equipment (primarily modems).

• (3) Data Concentration Equipment (primarily multiplexers and concentrators).

• (4) Redundancy and Reliability Aids (switches and line restoral units).

• (5) Automatic Assistance Devices (automatic answering and calling units).

• (6) Specialized Devices (security devices, speed and code converters, protocol converters, data access arrangements, speech-plus-data units).

• (7) Integrating Components.

On the whole, the book is pretty well organized along the functional line, both in the chapters and in the sections inside a chapter. The treatment is at a rather practical level without going too much into the theory. Lots of real-world applications are included to illustrate how the different devices can be employed. Diagrams are also used throughout without any reservation. This makes the book quite easy to follow, especially for those working in the field.

Nevertheless, it is the feeling of this reviewer that this book is not for the beginners. The author pointed out in the Preface that there is “a comprehensive introductory section which covers the fundamental concepts common to all phases of data communications.” With 16 sections covering a diverse range of topics (e.g., power measurements, transmission codes, ISO Reference model) all being crammed into 71 pages, the treatment is necessarily brief and hasty. In other parts of the text, the emphasis is usually on the details rather than an exposition of the basic concept.

Therefore, it is fair to say that this book assumes a certain level of mature understanding of the data communications field on the part of the reader. When used for courses at the upper-undergraduate or first-year-graduate level, as suggested by the author, this book must be supplemented by some other more basic texts. In this case, the review questions at the end of each chapter will be a useful source for classroom discussions or homework assignments.

Despite the shortcomings, this reviewer would recommend this book to students or practitioners as a general reference for its wealth of practical information and real-world application examples.