Page 9 - DCAP406_DCAP_207_Computer Networks

Computer Networks/Networks

Notes a large system of separate but interconnected computers do the job. These systems are called
computer networks. The two computers are said to be interconnected if they are able to exchange
information. The connection between the computers need not be only via a copper wire or fiber
optics or microwaves. A communication satellite can be used for networking the computers.

1.1 History of Computer Networks

Following is a brief history of computers, networking and telecommunication milestones:

1897: CRT (Cathode Ray Tube) credited to Braun
1900–1915: Teletype (telegraph 5 bit)
1915–1020: ARQ (Automatic Repeat request) credited to Van Duuren

1930–1940: ENIAC credited to DOD/MIT
1950s: SAGE (Semi-Automatic Ground Environment) MIT 1950s
1960s: Transistorized Computers–2nd Generation
1961: CTSS (Compatible Time Sharing System) credited to Cobato/MIT

1965: Auto Equalization Techniques of Phone lines credited to Lucky et al.
1966: Fiber Glass credited to Kao & Hockman
1967: Integrated Circuits Computers–3rd Generation
1968: Carterfone–FCC Decision in

1969: A group of DoD researchers linked four computers at UCLA, SRI, University of Utah
and the UCSB. They created a network to communicate with one another about government
projects. The network was part of the DoD’s Advanced Research Project Agency, and was
dubbed ARPAnet.
1972: More than 50 universities and military agencies were linked together on the network.
For a short period of time, it was a top secret defence project, ensuring that computers
could talk to each other in the event of a nuclear attack. The communication system
between the sites was called email and was invented by Ray Tomlinson of Bolt, Berank
and Newman.

1973: The defence project links were extended to Norway and England.
1974: Transmission Control Protocol (TCP) was published and the military and educational
links diverged. Organizations like NASA began to experiment with computer networks,
and the networks began to interconnect and the name Internet was coined.
1976: The Queen sends an email from RSRE Malvern.
1983: TCP/IP become the protocol standard for ARPAnet. Scott Fahlman invents the smiley
to convey emotions in email.
1984: In the US, the NSF built high speed, long distance lines that connected supercomputer
sites across the USA. These eventually replaced the original ARPAnet. In time, NSFnet was
joined by other networks at dozens of universities, research laboratories and high-tech
companies. The system for assigning names to computers on the network was introduced
— DNS. JANet was launched to connect British Universities.
1986: The NSF established its own faster network NSFnet and Network News Transfer
Protocol (NNTP) was introduced making on-line interactive discussion a reality. Backbone
speed was 56 Kbps.

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