Data Communications

· Is the process of transferring digital information between two or more points.

Development Of Data Communications

· 1837 -       Samuel F.B. Morse invented the telegraph
· 1849 -       low speed telegraph printers were invented
· 1860 -       high speed telegraph printers were invented at a rate of 15 bps.
· 1874 -       Emile Baudot invented a telegraph multiplexer , which allows signals from six different telegraph       machines to be transmitted simultaneously over a single wire.
· 1876 -       telephone was patented by Alexander Graham Bell.
· 1899 -       Marconi was able to send telegraph messages using radio waves.
· 1940 -       the first general -purpose computer was invented in the Bell Laboratories. With the collaboration of       the Harvard University and International Business Machines Corporation (IBM).
· 1951 -       UNIVAC computer was developed by Remington Rand .

Standard Organizations For Data Communications

ANSI - American National Standards Institute

· member of ISO
· deals with encryption activities
· office systems
· programming languages
· magnetic storage
· OSI model's Data Link & Network Layers (X3S3 committee)

· OSI sponsor
· Member of the International Telecommunications Union (ITU)

CCITT US - National Committee coordinates US participants.
National Communications Systems (NCS), a consortium of federal agencies with State Dept. CCITT voting member

· Data Comm. Networks

NCS works closely with EIA, ISO and CCITT
EIA - Electronics Industries Association

· Hardware oriented trade association
· Responsible for the development of RS( recommended standards) for data com and telecoms.
· OSI model
· Physical layer (TR-30)

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