Evolution of a data network

A star network centred around ICL equipment was built in 1972 at Plessey, UK. The development of the network from a system providing dial-up access for 37 terminals, to one supporting over 300 is described. The network has progressed from the use of BPO-supplied modems, to higher-speed modems and time-division multiplexers, and further to statistical multiplexers. The growth of transaction processing and online user data entry facilities have meant the introduction of multichannel modems. Network integrity, diagnostics and fault-finding features are discussed. The next major development stage will be the provision of a routing/switching capability for all connected terminal devices.