Personal computers and information networks

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In the 1950s powerful computing machines were used in America, the Soviet Union and other developed countries. They were hugely expensive but they offered unequalled processing power for academic and military research. Access to these machines was limited, so researchers started ‘time-sharing’. This meant that users could simultaneously access a mainframe computer through a series of terminals, although individually they had only a fraction of the computer’s actual power at their command.

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As the number of central computers grew, with a corresponding number of users, a serious need arose for networking between them. This coincided with a Cold War fear in the US that they needed to develop a communications system that could not be affected by a Soviet nuclear attack. The Advanced Research Projects Agency (ARPA) was founded in 1958, funded by the US Department of Defence. Among its projects was a remit to test the feasibility of a large-scale computer network, and so it invited a number of American computer hosts to join ARPANET. This network of a few mainframe machines formed the foundations of the Internet and later linked with similar networks across the world, such as ALOHAnet in Hawaii.

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The work at ARPA overlapped with similar work by computer networking expert Paul Baran. In 1959 Baran joined an American think tank, the RAND Corporation, and began to design a communications network, the components of which would continue to function even if parts of it were destroyed. His revolutionary ‘distributed network’ design allowed segments of information to take a variety of paths to their final destination, so that no central computer or pathway could be brought down to cause a complete communications failure.

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Baran’s work also coincided with work by Donald Davies, a British physicist at the National Physical Laboratory (NPL) in Teddington. His pioneering work during the 1960s on switching mechanisms effectively enabled computer files to be broken up into small segments (or ‘packets’ as he named them), distributed across a network, and then reordered back into a single file at their destination. This is the basis on which the Internet works today.

As the technical systems and communications protocols developed, a number of other networks formed, such as National Science Foundation Network (NSFnet), European UNIX Network (EUnet) and the UK’s Joint Academic Network (JANET). A rapid but unintended consequence of the growth of these networks was the use of e-mail as users quickly realised the potential of the network as a tool for instant communications. They sent personal messages and began mailing lists on specific topics. One of the first really big mailing lists was ‘SF-LOVERS’ for science-fiction fans. Now the network had truly transformed, becoming a way to gossip and communicate, rather than a way of accessing expensive computing power.