Abstract: A LAN priority control system is described which uses an interrupt priority control structure which suspends transmission of a packet from a lower priority node and allows a higher priority interrupting node, which desires to transmit a higher priority message, to obtain rapid access to the transmission medium and to transmit the message. The message is interrupted using a within packet interrupt which is taken to include any command which results in the transmission of a packet onto a common-medium being halted before the complete packet has been transmitted. In addition, the priority of nodes can be adjusted by a centralized network manager or by intelligent terminals distributed among the nodes, allowing priorities to be adjusted at nodes to correspond to the relative priorities of messages currently at these nodes rather than having a fixed allocation of priorities. In a token ring implementation, suspension of the message causes a busy token to be released which recirculates round the ring.

Abstract: Apparatus for conducting Ordering Trials including a set of counters each incorporating an electrical circuit element which covertly identifies that counter and a box having locations for receipt of the counters. The counters and locations are fitted with plugs and sockets which are interengageable and permit the circuit element to be connected to electrical read-out circuitry which includes circuitry for identifying which counter is in which location. An arithmetic unit operating according to a predetermined algorithm is connected to the output of the interrogation circuitry to provide a measure of the result of a trial. The invention is concerned with a form of interrogation circuitry which permits a direct digital readout to be attained.