Data Communications: The First 2500 Years

It is of course well−known that it was always possible to communicate very important signals over long distances with comparatively primitive means, e.g. by sounding church bells, giving smoke or fire signals, or by waving flags. It is clear that all these methods are limited in their possible uses: they are all relatively crude broadcast methods, that cannot but give a small set of pre−defined messages. It would be interesting to see, therefore, what historical record there is of methods and techniques that make point−to−point signaling of arbitrary messages possible. For this, a number of enabling techniques had to be developed first. These include: • Methods for relaying messages point to point, instead of broadcasting them. • Methods for encoding arbitrary information, e.g. in an alphabet, or in a vocabulary that has been optimized for a particular type of signaling.