Flexinet: a token bus protocol for local area networks interconnecting low cost data communicating devices

Local area network technology has to date generally focused on the problems of interconnecting high speed computing devices. Thus, where the connection of (primarily) low speed devices to a network is required, this has to be achieved by means of a star wired concentrator. The LAN protocol described in this paper is designed to exploit the topological advantages of direct connection to the net without incurring the high costs associated with direct connection to one of the established IEEE standard design. The protocol, Flexinet, employs token passing for medium access control on a bus. Advantage is taken of the short data frames involved in terminal interaction to minimise the hardware and software costs of the access units. A prototype version of the network has been built using simple 8 bit microprocessors and support chips.