Abstract: A serial data routing device for use in routing serial data between a computer and a peripheral device. The data routing device includes a computer data converter which communicates data under the USB protocol with a computer and which converts data received from the computer into converted computer data. A peripheral data converter is also included which communicates data under the USB protocol with the peripheral device and which converts data received from the peripheral device into converted peripheral data. A data router is provided in communication with the computer data converter and the peripheral data converter and transfers converted computer data and converted peripheral data between them. It includes a data routing controller which controls the routing of the converted computer data and the converted peripheral data between the computer data converter and the peripheral data converter such that the computer and peripheral device operate as though directly connected by a USB bus.

Abstract: A servo-amplifier has a RS232C-communication I/F circuit, a RS422 (RS485) communication I/F circuit, and a CPU 11. The CPU 11 of this servo-amplifier fetches data received by the RS232C-communication I/F circuit into a local station, converts the received data to communication data for RS422 (RS485) and transmits the converted data from the RS422 (RS485) communication I/F circuit to other stations, converts the data received by the RS422 (RS485) communication I/F circuit to communication data for RS232C and transmits the converted data from the RS232C-communication I/F circuit to other stations.

Abstract: A distributed system structure for a large-way, symmetric multiprocessor system using a bus-based cache-coherence protocol is provided. The distributed system structure contains an address switch, multiple memory subsystems, and multiple master devices, either processors, I/O agents, or coherent memory adapters, organized into a set of nodes supported by a node controller. The node controller receives transactions from a master device, communicates with a master device as another master device or as a slave device, and queues transactions received from a master device. Since the achievement of coherency is distributed in time and space, the node controller helps to maintain cache coherency. In order to reduce the delays in giving address bus grants, a bus arbiter for a bus connected to a processor and a particular port of the node controller parks the address bus towards the processor.

Abstract: A multiphase IEEE 1394 network of nodes requires all nodes to broadcast their current understanding of the phase of the bus (e.g., odd or even). Even if a node is not requesting ownership of the bus, it must send a message that indicates which phase that node believes to be the current phase of the network. If a node that does not need ownership of the bus believes the bus currently is in the odd phase, then that node will transmit a “None_odd” message indicating the node's understanding that the bus is in the odd phase. Similarly, if a node that does not need the bus believes the bus currently is in the even phase, then that node will transmit a “None_even” message indicating the node's understanding that the bus is in the even phase. Preferably, the current bus owner will not switch the phase of the bus until all nodes have a correct understanding of the current phase of the bus.

Abstract: A method and apparatus for transferring data using an on-chip bus is presented. A data transaction consisting of an address and data packet is transmitted on an on-chip bus which is a two-wire serial bus consisting of an address line and a data line that connects a plurality of satellites in a daisy-chain fashion to a central source. Each on-chip satellite is associated with a unique identifier. In response to a determination that the transaction is accepted by the satellite, which is determined by the address in the address packet positively comparing to a unique identifier for the satellite, the address packet is modified to provide a positive acknowledgment of a receipt of the address packet back to the central source of the transaction. The address packet is modified by clearing the stop bit of the address packet, i.e. gating off or negating the stop bit. Alternatively, the address packet is otherwise modified to indicate the acceptance of the packet.

Abstract: A distributed system structure for a large-way, symmetric multiprocessor system using a bus-based cache-coherence protocol is provided. The distributed system structure contains an address switch, multiple memory subsystems, and multiple master devices, either processors, I/O agents, or coherent memory adapters, organized into a set of nodes supported by node controllers. A node controller receives transactions from a master device, communicates with a master device as another master device or as a slave device, and queues transactions received from a master device. Since the achievement of coherency is distributed in time and space, a node controller helps to maintain cache coherency. The node controllers must give simultaneous address bus grants to the address switch to initiate a snoop. Livelocks are detected individually by each node controller in an uncoordinated manner from a lack of successful snoops from the address switch to the node controllers.

Abstract: A data processing system includes at least first and second nodes and a segmented interconnect having coupled first and second segments. The first node includes the first segment and first and second agents coupled to the first segment, and the second node includes the second segment and a third agent coupled to the second segment. The first node further includes cancellation logic that, in response to the first agent issuing a request on the segmented interconnect that propagates from the first segment to the second segment and the second agent indicating ability to service the request, sends a cancellation message to the third agent instructing the third agent to ignore the request.