Communications Technology Handbook, 2nd Edition

23 Networks

Until the expansion of the use of computers in communications in the 1970s, typical systems were centred upon the telephony networks on the PTTs (the national post, telegraph and telephony organisations), public switched telephone networks (PSTN), and radio services. The PTT networks connect individual subscribers to a second specified or addressed subscriber, so that the service is often described as narrow casting. While the radio services might well be intended for a specified receiver, the very nature of the transmission precludes specific addressing, so that the term broadcasting applies. The introduction of computer to computer communications completely changes the concept of a network. The communication of a computer with ...