900 B.C.
A postal service is used for governmental purposes in China.
500 B.C.
In ancient Greece trumpets, drums, shouting, beacon, fires, smoke signals, and mirrors are used for message transmission.
4th century B.C.
Aeneas Tacitus, a Greek military scientist and cryptographer, invented an optical communication system that combines water and beacon telegraphy. Torches indicated the beginnings and the ends of a message transmission while water jars were used to transmit the messages. These jars had a plugged standard-size hole drilled on the bottom side and were filled with water. As those who sent and those who received the message unplugged the jars simultaneously, the water drained out. Because the transmitted messages corresponded to water levels, the sender indicated by a torch signal that the appropriate water level had been reached. The methods disadvantage was that the possible messages were restricted to a given code, but as the system was mainly used for military purposes, this was offset by the advantage that it was almost impossible for outsiders to understand the messages unless they possessed the codebook.
With communication separated from transportation, the distant became near. Tacitus' telegraph system was very fast and not excelled until
For further information see Joanne Chang & Anna Soellner, Decoding Device,
3rd century B.C.
Wax tablets are used as writing material in Mesopotamia, ancient Greece, and Etruria.
2nd century B.C.
In China paper is invented.
1st century B.C.
The use of codices instead of scrolls - basically the hardcover book as we know it today - is an essential event in European history. To quote accurately by page number, to browse through pages and to skip chapters - things that were impossible when reading scrolls - becomes possible.
In the computer age we are witnesses to a kind of revival of the scrolls as we scroll up and down a document. The introduction of hypertext possibly marks the beginning of a similar change as has taken place with the substitution of scrolls with codices.
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Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to