A recirculating, synchronous TDM (time division multiplexed) backbone loop operating at 1 Mbps that supports multiple 9600 baud point-to-point connections, and multiple low bit rate packet channels is described. Slots are deterministically allotted to groups of devices and any medium access protocol suitable for the ring topology can be used to regulate access to the transmission channel. Nodes on the backbone are interconnected through fiber optic or atmospheric optical links. The objective of the network is to satisfy the demands of a typical computing environment, viz., to offer a terminal distribution system and to simultaneously support multiple low bit rate packet channels. Devices communicate with the network through RS-232C serial lines.