Abstract: Collections of articles or entities are represented on a video display in a manner that allows one to view the relationship, if any, between those articles. One embodiment uses circular representations to model set membership of the entities in one or more of the collections. Another embodiment displays many-to-many and one-to-many relationships between the entities and the collections using two overlapping sets of connective representations with icons displayed at the overlaps to indicate the relationship.

Abstract: A dataframe filter is provided a local area network bridge to monitor the dataframes transmitted on one network to determine those dataframes destined to be communicated to another network by the network bridge. The filter receives and examines the destination address of each dataframe communicated on the one filter and, searching through a database maintained by the filter, determine whether the destination address is located on the second network and, if so, signals the bridge to copy the dataframe to the second network.

Abstract: A data stream is received by a first in a series of repeating devices and retransmitted from repeating device to repeating device. As the data stream is retransmitted, the data stream accumulates jitter. A jitter reduction apparatus therefore is used after a series of repeating devices to substantially reduce the accumulated jitter. The jitter reduction apparatus receives the data stream, stores the recognized data, then retransmits the data using a recovered clock signal. According to one embodiment, the recovered clock signal is the clock signal of the original data transmission. According to another embodiment, the recovered clock signal is derived from the data stream as input to the first of the series of repeating devices. Such derived clock signal serves as an estimate of the original data source clock signal. By using a recovered clock signal (e.g.

Abstract: A dataframe filter is provided a local area network bridge to monitor the dataframes transmitted on one network to determine those dataframes destined to be communicated to another network by the network bridge. The filter receives and examines the destination address of each dataframe communicated on the one filter and, searching through a database maintained by the filter, determine whether the destination address is located on the second network and, if so, signals the bridge to copy the dataframe to the second network.

Abstract: Two message security methods and apparatus for the same for token ring local area networks. According to a first method, a port in a ring central controller examines the source and destination addresses of a received data packet and stores a received data packet and replaces the data portion with unrelated data bits only if the address does not match that of the attached user station. In another embodiment, the port scrambles the data portion of the received data packet if the addresses do not match.

Abstract: A security system for local area networks (LAN) to prevent eavesdropping of or to control access to LAN traffic at repeater or concentrator ports. The security system determines which repeater ports are to have security activated according to a given set of criteria. For ports with security activated, the contents of the data field of data frame transmitted from the repeater port to the local device are replaced with an arbitrary bit pattern.

Abstract: A hub network system is provided for communication between nodes. The system can be used, e.g., when one node can be configured for baseband bus topology communication, such as LocalTalk.TM. communication. The node can communicate using the entire bandwidth of the medium, such as 230 Kbps bandwidth, even though other nodes are connected to the network using the hub card. Preferably, the hub card includes a multiprocessor system with a shared memory for providing high internal effective bandwidth communication, such as 15 Mbps communication. A proxy scheme is provided so that the hub topology is transparent to any node which can operate as though it were configured in a bus topology.

Abstract: A security system for local area networks (LAN) to prevent eavesdropping of or to control access to LAN traffic at repeater or concentrator ports. The security system determines which repeater ports are to have security activated according to a given set of criteria. For ports with security activated, the contents of the data field of data frame transmitted from the repeater port to the local device are replaced with an arbitrary bit pattern.

Abstract: A balanced L-section low-pass common mode filter is connected in series with balanced data I/O lines to remove common mode signals from balanced line difference mode signals. The filter includes input and output series transformers configured so that the magnetic fields in the transformers are subtractive for out-of-phase difference mode signals and additive for in-phase common mode signals and a shunt transformer coupled to ground configured so that the magnetic fields in the transformer are additive for out-of-phase difference mode signals and subtractive for in-phase common mode signals. Accordingly, the difference mode signals are not attenuated and common mode signals react to a short circuit to ground and are thereby attenuated by the filter.

Abstract: A balanced T-section low-pass common mode filter is connected in series with balanced data I/O lines to remove common mode signals from balanced line difference mode signals. The filter includes input and output series transformers configured so that the magnetic fields in the transformers are subtractive for out-of-phase difference mode signals and additive for in-phase common mode signals and a shunt transformer coupled to ground configured so that the magnetic fields in the transformer are additive for out-of-phase difference mode signals and subtractive for in-phase common mode signals. Accordingly, the difference mode signals are not attenuated and common mode signals react to a short circuit to ground and are thereby attenuated by the filter.