Abstract: A computer network is disclosed in which a plurality of computer stations are interconnected by a single bi-directional bus and wherein access to the bus is controlled by the computer stations themselves through an adapter unit at each station. Each adapter unit includes a microcontroller, a transmitter, a receiver, a send buffer, a receive buffer, a line activity indicator, a pulse producing device, a read circuit and a write circuit. Each adapter unit has a unique assigned number. When the network is running and stable, control of the bus is continually passed from one live adapter unit to another in numerical sequence according to its unique assigned number and the bus is active with messages, control signals or status signals separated by relatively short intervals. If only one adapter unit is live, control is continually passed to itself.