Abstract: A secure method for transmitting data on an isochronous network in which data is spread in successive frames in a manner known to the sender and receiver but unknown to other nodes on the network. In one embodiment, some or all bits which comprise a byte are transmitted in different channels (i.e. time slots) so that the bits which comprise a byte are spread over several channels in a pattern known to the sender and receiver but not to unauthorized parties on the network. This bit spreading can be performed in real time and without latency or performance problems. In another embodiment, the channel or channels assigned for communication between two nodes on the network change in a sequence known to the sending and receiving nodes but not known to unauthorized parties.

Abstract: A server, and a number of client stations interconnected by a token ring network, specifically an FDDI-II network. The FDDI-II ring is connected in a star-ring topology, with the server and the clients preferably connected to the network through a wiring closet, as is the usual practice for such a topology. The server has separate physical connections to the single FDDI-II ring with each physical connection to the ring providing access to a separate physical domain. This partitions the same ring into different physical domains, so that an increase in the total effective bandwidth of the network is achieved by the server reallocating the same isochronous bandwidth in each of the domains for reuse by the server. An allocation of bandwidth in an isochronous channel in one domain can be reused by the server in another physical domain.

Abstract: A ring network with dual homing connections to the network from one or more nodes via physically separated concentrators.

Abstract: A communications adapter receives and transmits simultaneously packet and/or isochronous data between two interfaces; a network and a host bus system. The adapter stores the isochronous and packet data in receive and transmit queues configured in a FDDI RAM buffer. A controller manages the transfers of the data into and out of the queues. A local bus interacts with the system to provide descriptors of addresses in the system for transfers of data out of the queues to the system or the network. The controller is programmable to provide a variable threshold for the transfer of data between the queues and the system or the network. A systems interface unit handles the transfer of data to/from the system and allows data to bypass the queues and directly access the system or the network.

Abstract: A communications adapter receives and transmits simultaneously packet and/or isochronous data between two interfaces; a network and a host bus system. The adapter stores the isochronous and packet data in receive and transmit queues configured in a FDDI RAM buffer. A controller manages the transfers of the data into and out of the queues. A local bus interacts with the system to provide descriptors of addresses in the system for transfers of data out of the queues to the system or the network. The controller is programmable to provide a variable threshold for the transfer of data between the queues and the system or the network. A systems interface unit handles the transfer of data to/from the system and allows data to bypass the queues and directly access the system or the network.

Abstract: A communications adapter receives and transmits simultaneously packet and/or isochronous data between two interfaces; a network and a host bus system. The adapter stores the isochronous and packet data in receive and transmit queues configured in a FDDI RAM buffer. A controller manages the transfers of the data into and out of the queues. A local bus interacts with the system to provide descriptors of addresses in the system for transfers of data out of the queues to the system or the network. The controller is programmable to provide a variable threshold for the transfer of data between the queues and the system or the network. A systems interface unit handles the transfer of data to/from the system and allows data to bypass the queues and directly access the system or the network.

Abstract: A method of switching multimedia data streams in response to requests to allocate or deallocate a user on a network receiving those data streams is herein described. The data streams are transmitted in master cycles, portions of each master cycle being allocated to each user. The relationship between the user and the portion of the master cycle is kept track of by means of a matrix method.

Abstract: The invention provides a method and apparatus by which the usage of an existing ring network is extended by implementing spatial reuse of the network bandwidth. By spatial reuse we mean that specific portions of the ring network may reuse the same bandwidth. Essentially, the invention is based on the realization that each station rarely needs to communicate with all the other stations that share its ring. Under normal conditions, a station requires the ability to send messages only to a subgroup of the total number of stations. If the ring network is thought of as a circle and if the communicating stations are contiguous, then these stations occupy only an arc on the circle. Outside this arc, the bandwidth assigned to these stations is not in use. Accordingly, the bandwidth can be reassigned to stations which form other, non-overlapping arcs.

Abstract: A method and system for call set-up and channel resource allocation between a plurality of parties in a multi-media conference call that consists of receiving notice that a Sender (the initiator of the conference) wants to commence a video conference. At that point, the number of channels required by the proposed call is determined. Subsequently, each requested participant is identified as available, busy, or no answer. If the receiver is available and sufficient channels are available, the call is set-up and the present members of the conference are notified of what channel each should transmit on and what channel(s) to listen to for the other participants. As each receiver is added, the Sender may conference with the present Receiver. If it is decided at this point, that the receiver will not participate in the conference, the call to that receiver may be terminated, and the procedure continues for other receivers until the full conference is set up. Individuals may leave the conference at any time.

Abstract: A microsequencer includes at least two program counters which access microinstructions stored in a memory system. A first program counter is cyclicly incremented to sequentially access microinstructions of a principal microprogram. When a particular microinstruction is accessed which indicates that a subroutine will be the next program to be executed, a branched-from address, representing the microinstruction calling the subroutine, is retained in the first program counter. An address representing the first instruction of the subroutine is loaded into a second program counter. The second program counter is then cyclicly incremented to sequentially access microinstructions associated with the subroutine. After the subroutine has been executed, the first program counter is re-enabled and cyclicly incremented so that the execution of the principal program is resumed in an orderly manner.