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Inglês Instrumental: Sistemas de Informação e CST-Redes
Professora: Valéria Bacalá Data: 29/04/2014
Aula VIII:. Simple Past
Objetivos:
Aprender, reconhecer e utilizar o simple past.
Learning activities
Simple Past
Leia o texto e em seguida responda a atividade.
Origins of the Internet
The Internet originated in the early 1970s as part of an Advanced Research Projects
Agency (ARPA) research project on “internet working. ” At that time, ARPA demonstrated the
viability of packet switching for computer-to-computer communication in its flagship network,
the ARPANET, which linked several dozen sites and perhaps twice that number of computers
into a national network for computer science research. Extensions of the packet-switching
concept to satellite networks and to ground-based mobile radio networks were also under
development by ARPA, and segments of industry (notably not the traditional
telecommunications sector) were showing great interest in providing commercial packet
network services. It seemed likely that at least three or four distinct computer networks would
exist by the mid-1970s and that the ability to communicate among these networks would be
highly desirable if not essential.
In a well-known joint effort that took place around 1973, Robert Kahn, then at ARPA,
and Vinton Cerf, then at Stanford, collaborated on the design of an internetwork architecture
that allowed packet networks of different kinds to interconnect and machines to communicate
across the set of interconnected networks. The internetwork architecture was based on a
protocol that came to be known as TCP/IP. The period from 1974 to 1978 saw four successively
refined versions of the protocol, which ARPA research contractors implemented and tested in
academia and industry, and version number four eventually became standardized. They used
the TCP/IP protocol initially to connect the ARPANET, based on 50 kilobits per second (kbps)
terrestrial lines; the Packet Radio Net (PRNET), based on dual rate 400/100 kbps spread
spectrum radios; and the Packet Satellite Net (SATNET), based on a 64 kbps shared channel on
Intelsat IV. The initial satellite Earth stations were in the United States and the United
Kingdom, but they subsequently activated additional Earth stations in Norway, Germany, and
Italy. They connected several experimental PRNETs, including one in the San Francisco Bay
area. At the time, no personal computers, workstations, or local area networks were available
commercially, and the machines involved were mainly large-scale scientific timesharing
systems. Remote access to time-sharing systems became available by terminal access servers.
FONTE: http: //www. diamondclear. com. au/help/glossary. html
