BKTCHDCM.RVW  930907

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"Technical Aspects of Data Communication", McNamara, 1988
mcnamara@world.std.com

Gee.  All these years I'd been thinking that data communications was pretty
technical all by itself.  However, I am willing to forgive a lot to a book
which finally covers trellis coding.  (There, that wasn't too hard, now, was
it?)

Actually, this is precisely the area that McNamara concentrates on.  This work
deals quite fully and completely with data communications--but only at the
"lowest" layers.  The emphasis is on the physical and link layers, to use the
terminology of the ISO (International Standards Organization) seven-layer
model.

The preface states that the book is for those who are about to design, program,
or purchase a data communications system, or who simply wish to know more about
data communications.  That it is.  Although the work deals with material that
is now almost universally buried "in the hardware", it is the basics of
telecommunications.  If you are working with data communications at higher
levels, you neglect these basics at your peril.

Although the material is clearly and distinctly delineated into chapters
(twenty-eight of them, in fact), an overall structure is not obvious.  This is
doubtless due to the nature of the material:  at this level, everything is very
interrelated.  This is not to say that the book is *dis*organized or confused. 
The chapters are quite clear as to contents, and the proper section for
reference is quickly found.  Topics covered include the basics, and history, of
asynchronous communications, UARTs (Universal Asynchronous Receiver /
Transmitter) and related circuitry, interfaces and standards, modem control,
telephone switching and signalling, error detection, synchronous communication,
link layer protocols, packet switching and local area networks.

It is probably not necessary for everyone who wants to buy a modem to know
everything in this book.  (On the other hand, it couldn't hurt.)  It might not
even be necessary for someone planning a multiplexed link between two
significant systems, but I'd be very hard pressed to suggest anything here that
you don't need in that case.  McNamara's writing, however, is very clear and
all of the book should be accessible to the intelligent reader; layman or
computer expert.

Third edition or not, the copyright data on the book is 1988.  It is bound to
show some signs of age.  The fact that McNamara is dealing with basics and
concepts, though, keeps anachronism to a minimum.  It is only occasionally that
you realize that 9600 bps is no longer considered a high-speed modem.  The real
wonder is that, while some of the technology might have progressed to a point
where a topic might be only of academic interest, none of the contents are
really "dated".

Some of the topics, such as local area networks, could stand some extra detail. 
On the other hand, once you start adding, where do you stop?  The material
included is basic and foundational, and other books can (and have) been written
on those related topics.  The one item missing from this tome is a strong
bibliography.  There are some references in some chapters.  A great many of
these, however, are journal citations, which may be difficult for the non-
academic to obtain.  With a bibliography, this would have been an absolutely
key text as an introduction to the field of data communications.  As it is, it
is still a great introduction, but the next steps are left to the reader.

I have no difficulty in recommending this work.  To the novice, it is an
excellent foundation for data communications study and work.  The large
commercial technical training firms will charge you in the region of a thousand
dollars for a course which gives you basically what you get in this book.  The
data communications professional will also find this a handy reference for the
basics.

copyright Robert M. Slade, 1993   BKTCHDCM.RVW  930907
 
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