Abstract: An arrangement for extending the range of a peripheral bus carrying message packets has a pair of extenders interconnected by a balanced transmission line for transferring signals directly between the peripheral buses without tracking the message packets. Typically, the peripheral buses are USB buses.

Abstract: A teaching system comprising student and teacher computer stations which are serially connected in a closed loop circuit. Each student computer and the teacher station comprises a computer device having an associated video monitor connectable thereto via an interface unit. A teacher controller device is provided at the teacher control station and has an output connected to the interface units to transmit an information network signal thereto to condition the interface units to place its associated student computer station to a preselected mode. A keyboard is associated with the controller device at the teacher control station for selecting the mode. A visual display on the controller indicates the selected mode to the teacher.