Precursors
The telegraph system is the first
fully digital communication system. Thus the Internet has precursors, such as
the telegraph
system, that date back to the 19th century, more than a century before the
digital Internet became widely used in the second half of the 1990s. The
concept of data communication – transmitting data between two different places, connected
via some kind of electromagnetic medium, such as radio or an electrical wire – predates the introduction
of the first computers. Such
communication systems were typically limited to point to point communication
between two end devices. Telegraph systems and telex machines can be considered early precursors of this kind of communication.
Fundamental theoretical work in data transmission and information theory was developed by Claude Shannon,
Harry Nyquist, and Ralph Hartley,
during the early 20th century.
Early computers used the technology
available at the time to allow communication between the central processing
unit and remote terminals. As the technology evolved, new systems were devised
to allow communication over longer distances (for terminals) or with higher
speed (for interconnection of local devices) that were necessary for the mainframe computer model. Using these technologies made it possible to
exchange data (such as files) between remote computers. However, the point to
point communication model was limited, as it did not allow for direct
communication between any two arbitrary systems; a physical link was necessary.
The technology was also deemed as inherently unsafe for strategic and military
use, because there were no alternative paths for the communication in case of
an enemy attack.
