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Chapter 21Electronic Communications Systems, 5th Edition

By: Wayne Tomasi


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Introduction Data Communications. The transmission, reception, and

processing of digital information.

Data. Information that is stored in digital form.

Information that has been processed, organized andstored.

Data Communications Network. Systems of interrelatedcomputers and computer equipment connected throughthe public telephone network or similar networkinfrastructure.

Any system of computers, computerterminals, or computer peripheral equipment to transmitand/or receive information between two or more locations.


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Network. A set of devices, nodes, or stationsinterconnected by media links.

Internet. A public data communications network used

by millions of people worldwide to exchange businessand personal information.

Intranet. Private data communications networks usedby many companies to exchange information among

employees and resources.World Wide Web (www). A server-based application

that allows subscribers to access the services offered bythe Web.


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History of Datacom 1753 One of the earliest means of communicating

electrically coded information through a 26 wire system.

1833 Carl Friedrich Gauss developed a system based on a5x5 matrix representing 25 letters.

1832 The telegraph (the first data communication system)was invented by Samuel F.B. Morse.

1840 The American patent for the telegraph was granted.

1844 The first telegraph line was established betweenBaltimore and Washington D.C. conveying the firsttelegraph message What hath God wrought!


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1849 The first slow-speed telegraph printer was invented.

1850 Western Union Telegraph Company was formed inRochester, New York, for the purpose of carrying codedmessages from person to another.

1860 High-speed printers (15 bps) became available.

1874 Emile Baudot invented the telegraph multiplexer thatallowed signals from up to six different telegraph machinesto be transmitted simultaneously over a single wire.

1875 The telephone was invented by Alexander Graham Bell


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1899 Guglielmo Marconi succeeded in sending radio(wireless) telegraph messages.

1920 The first commercial radio stations carrying voice

information were installed. 1930s Konrad Zuis, a German engineer, demonstrated a

computing machine.

1940 Bell Laboratories developed the first special purpose

computer using electromechanical relays for performinglogical operations.

1946 The first modern-day computer (ENIAC) wasdeveloped by J. Presper Eckert and John Mauchley at theUniversity of Pennsylvania.


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1949 The U.S. National Bureau of Standards developed thefirst all-electronic diode based computed capable ofexecuting stored-programs.

1950s Batch processing computers used punched cards asan input interface, printers as an output interface, andmagnetic tape reels for data storage.

The first general purpose computer in the formof an automatic sequence-controlled calculator wasdeveloped jointly by Harvard University and IBMCorporation.

1951 Remington Rand Corporation built the first mass-produced electronic computer (UNIVAC).


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1960s Batch-processing system were replaced by on-lineprocessing systems with terminals connected directly tothe computer through serial and parallel communication

lines. 1968 The landmark US Supreme Court Carterfone decision

allowed non-Bell (non AT&T) equipment to be connectedto the vast AT&T network.

1969 The internet began to evolve at the AdvancedResearch Projects Agency (ARPA) through the ARPANET.

1970s Microprocessor-controlled microcomputers weredeveloped.


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1980s Personal computers became an essential item in thehome and the workplace. Since then, the need to exchangedigital information, and consequently, the need for data

communication circuits, networks, and systems increasedexponentially.

1983 AT&T agreed in a court settlement to divest itself ofoperating companies that provide basic local telephoneservice to various geographic regions of the US as a result

of an anti-trust suit filed by the federal government. Mid 1980s to 1995 The United State National Science

Foundation (NSF) funded a high-speed backbone calledthe NSFNET.


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1989 Tim Berners-Lee and Robert Cailliau build theprototype system which became the World Wide Web atCERN.

1991 Anders Olsson transmits solitary waves through anoptical fiber with a data rate of 32 billion bits per second.

1992 Neil Papworth sends the first SMS (or text message).

1994 Internet radio broadcasting is born.

1999 45% of Australians have a mobile phone.

Sirius satellite radio is introduced


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2001 First digital cinema transmission by satellite in Europeof a feature film by Bernard Pauchon and Philippe Binant isundertaken.

2003 Apple launches the iTunes Music Store and sells onemillion songs in its first week.

MySpace is launched.

2004 What would become the largest social networkingsite in the world, Facebook is launched.

2005 Youtube, the video sharing site is launched.

2006 Twitter, microblogging is introduced.


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