Microcom Systems, Inc.

Bell & Howell Company

Gary B Videlock

Mark J Freitas

Russell C Gocht

John R Flint

Kenneth L Hendrickson

Paul H Friedrich

Douglas Wainer

AnneMarie Freitas

John J Carroll

Tom P Gloria

Stuart F Schwalb

Gary S Slutsky

Philip P Gailinas

Harold L Kabb

Ishfaq A Niazi

A multiport source routing token ring bridge is provided which permits a single local area network bridge to interconnect to multiple remote bridges without limitations on the number of rings and bridges interspersed between a data packet's source and its intended destination. The bridge receives a packet and then scans the packet for ring-in information which matches the ring to which the bridge is attached. If this match is not successful, then the packet is not passed to the software and the address recognize and frame copy bits at the end of the packet are not set. If the match is successful, then the bridge number and next ring-in (or ring-out) segment information from the packet are used as addresses to a static RAM array. The array is preprogrammed with all valid bridge number and ring-out combinations which may be accessed by the multiport source routing bridge. If addressing of the array produces a valid indication, then the packet is passed to software for forwarding to the appropriate local area network or wide area network ports. On the other hand, if the address does not produce an indication that it can be reached through the bridge, then the hardware parses the packet to extract the next ring and bridge information, and repeats the above process until either a complete match is found and the packet is passed, or the information field is exhausted and the packet is finally rejected.

Multiport source routing token ring bridge apparatus

A bridge/router for use in bridging and routing data among one or more local area networks and a wide area network is disclosed. The bridge/router utilizes a data compressor adapted to compress data in frames adding an end of compression marker after each frame. The bridge/router provides data transmission speeds as fast as 2.048 Mbps and includes means for inhibiting the end of compression marker, while generating a data structure with each frame which is compressed with the frame of data. The data structure includes information representing the number of bytes of raw data in the corresponding frame so that on decompression the decompresser knows the number of bytes to provide in the resulting frame of decompressed data, thus avoiding the need for the end of compression marker. By inhibiting the marker compression is performed with greater efficiency.

High speed data compression and transmission for wide area network

An apparatus and method for learning and filtering destination and source addresses in a local area network (LAN) system is provided to facilitate the transfer of information packets from one local area network to another. The apparatus provides a link between two (or more) remotely located LANS through the use of a LAN bridge. The apparatus has a LAN controller interface, a microprocessor, a state machine and one or more content addressable memories which function to monitor an information packet received from the LAN. One such apparatus is connected to each of the LANs to be interfaced and each of these apparatus to each other in order to communicate messages between the LANs. Upon detection of an information packet, the apparatus examines both the source and destination addresses of the packet. The source address is compared to a dynamically generated table of source addresses and then compared to the incoming destination address. If the destination address is found in the table of source addresses, than the packet is destined for a node on the local LAN and thus will not be sent over the bridge between the two LANs. If, on the other hand, the destination address is not in the table, the packet is forwarded to the remote LAN.

Apparatus and method for learning and filtering destination and source

A distributed processor control system for use with a microimage recording apparatus includes a system control unit, a machine control unit and an operator control unit. The system control unit includes a microprocessor that provides supervisory or master control for the overall distributed control system. The machine control unit includes at least one microprocessor for controlling the operations of a plurality of electromechanical components within the microimage recording apparatus in response to commands and parameters provided by the system control unit and for providing status and error information and requests to the system control unit. The operator control unit includes a microprocessor for controlling the display of operational status and error indications and messages for viewing by an operator and for receiving manual operator entries for enabling normal operation of and diagnostics for the microimage recording apparatus. A shared memory device is utilized for bidirectional communications between the system control unit and the machine control unit. An asynchronous, bidirectional serial link enables bidirectional data transfer between the system control unit and the operator control unit.

Control system for microimage recorders

Growing community of inventors

Foxborough, MA, United States of America

Gary B Videlock