Abstract: The present invention is directed to a method and apparatus utilizing a two-level, multi-tier system bus. The multi-tier system bus of the present invention allows for the flow of information to be managed among plural processors by connecting processors within modules on a local bus, which is then connected to the system bus by way of a gateway. A system controller and arbitrator is provided for arbitrating access to the system bus by the various modules. The present invention, by way of the system controller initiates and performs control actions and allows the system bus to be freed from transmission delays of prior approaches associated with transmitting data packets.

Abstract: Power is conserved in a data processing system that includes a processor core and system circuitry coupled to the processor core. A first method for conserving power includes entering a low power state by the processor and the system circuitry and enabling bus arbitration by the processor while the processor core remains in the low power state. One embodiment further contemplates a method of conserving power by granting bus access to a requesting device and entering a power conservation mode by the processor core in response thereto. Bus operations are then performed while the processor core remains in the power conservation mode. Another embodiment contemplates a method of debugging a data processing system in which a debug state is entered by the processor and the system circuitry and, thereafter, bus arbitration is enabled by the processor while the processor core remains in the debug state.

Abstract: A data processor has a first bus master module, first bus slave module and first bus right arbitrating circuit connected to a first bus, a second bus master module, second bus slave module and second bus right arbitrating circuit connected to a second bus, and a bus bridge circuit connecting the first and second buses. The bus bridge circuit has a first transfer controller, responsive to an access request from the first bus to the second bus, for obtaining a bus right of the second bus, and a second transfer controller, responsive to an access request from the second bus to the first bus, for obtaining a bus right of the first bus. The second bus has a first path connecting the second bus slave module and the first transfer controller and a second path connecting the second bus master module and the second transfer controller.

Abstract: A mini PCI module includes a mini PCI card and a mini PCI slot for the mini PCI card to be inserted into. The mini PCI card includes 124 signal pins and an antenna pin set. The mini PCI slot includes 124 signal connection ends corresponding to the 124 signal pins, and an antenna connection end set corresponding to the antenna pin set for electrically connecting to an antenna set.

Abstract: In one embodiment of the present invention, a method may include separating incoming transactions to an agent of a coherent system into at least a first channel, a second channel, and a third channel, based upon a type of the incoming transactions. The incoming transactions may be sent by a peer device coupled to the coherent system. By separating the transactions based on type, deadlocks may be avoided.

Abstract: Disclosed a processes and an apparatus which relates to an improved technique for sharing a computer resource.

Abstract: A frequency manager automatically selects a clock frequency for each device or bus, or for a plurality of devices or buses, in a system, based on various factors and objectives. These factors and objectives can include optimizing performance of the devices without exceeding the system's power/thermal budget. The frequency manager can then control circuits that generate and provide clock signals having the selected frequency(ies) to these devices or buses. For example, in a system that is less than fully populated with devices, embodiments of the invention can select higher clock frequencies than a fully populated system would utilize. Some embodiments of the invention select higher clock frequencies for high-bandwidth devices than for low-bandwidth devices. Other embodiments use information about application programs that will be executed by systems, such as which devices these application programs will frequently access, to select higher clock frequencies for the frequently accessed devices.

Abstract: A frequency manager automatically selects a clock frequency for each device or bus, or for a plurality of devices or buses, in a system, based on various factors and objectives. These factors and objectives can include optimizing performance of the devices without exceeding the system's power/thermal budget. The frequency manager can then control circuits that generate and provide clock signals having the selected frequency(ies) to these devices or buses. For example, in a system that is less than fully populated with devices, embodiments of the invention can select higher clock frequencies than a fully populated system would utilize. Some embodiments of the invention select higher clock frequencies for high-bandwidth devices than for low-bandwidth devices. Other embodiments use information about application programs that will be executed by systems, such as which devices these application programs will frequently access, to select higher clock frequencies for the frequently accessed devices.

Abstract: A scheduler stores data to be scheduled. The scheduler may include an array that identifies relative priorities among the queue entries according to a first priority scheme, such as by age. The scheduler also may include a priority register array identifying relative priorities among the queue entries according to a second priority scheme, such as by data type. A plurality of detectors coupled to the array and to the priority register array may determine which data is to be scheduled next.

Abstract: A processor chip is provided. The processor chip includes a plurality of processing cores, where each of the processing cores are multi-threaded. The plurality of processing cores are located in a center region of the processor chip. A plurality of cache bank memories are included. A crossbar enabling communication between the plurality of processing cores and the plurality of cache bank memories is provided. The crossbar includes an arbiter configured to arbitrate multiple requests received from the plurality of processing cores with available outputs. The arbiter includes a barrel shifter configured to rotate the multiple requests for dynamic prioritization, and priority encoders associated with each of the available outputs. Each of the priority encoders have logic gates configured to disable priority encoder outputs. A method for arbitrating requests within a multi-core multi-thread processor is included.

Abstract: A method is provided for allocating system resources across multiple nodes of a system communicating through a hardware device. The method provides for allocation of transaction units or identifiers in an allocating component for use in a multiple target component which may be in a distinct target node within the multiple node system. Based on the operations or requests that a target node receives from multiple external request source nodes, each requiring the use of target transaction unit objects such as transaction identification bits, the method provides inclusion of such information in the initial request to a target node which allows any data transmission between the source node and the target node, or the target node and the source node to be accomplished without any further intervention by the allocating component. Such component may be a local memory control agent or device.

Abstract: A bus connection circuit is connected by a bus to a bridge circuit having a plurality of pre-fetch buffers to access memory. A plurality of request queues and a plurality of request signal outputs and grant signal inputs are provided in a single bus connection device. By means of the single bus connection device, a plurality of pre-fetch buffers of a bridge circuit can be utilized effectively, wasted read requests corresponding to retry responses from the bridge circuit can be decreased, and consequently wasted use of a PCI bus can be reduced.

Abstract: A method and apparatus for improved performance for handling priority agent bus requests when symmetric agent bus parking is enabled is disclosed. In one embodiment, a modified priority agent may be used. The modified priority agent may assert an unused symmetric agent bus request when it asserts its priority agent bus request. When a symmetric agent parks on the bus, continually asserting its symmetric agent bus request, the assertion of the otherwise unused symmetric agent bus request may cause the symmetric agent to withdraw its symmetric agent bus request. This may reduce bus response time for subsequent modified priority agent bus requests.

Abstract: An apparatus and method for maintaining a circular FIFO (first-in, first-out) queue in an I/O (input-output) subsystem of a computer system such as a server, workstation, or storage machine. The queue is coupled to a bypass circuit, used to provide access to data items out of the order in which they were stored in the queue, thus bypassing the latency inherent in retrieving the items from the queue. Control logic maintains write and read pointers indicating locations in the queue for writing and reading data items. The write pointer is incremented upon every data event to the queue, thereby maintaining a history of data that has been written to the queue, which is useful for diagnostic purposes. A history flag is maintained to indicate whether the write pointer has wrapped around the addresses in the queue, indicating whether all data items in the queue are valid for diagnostic purposes.

Abstract: A Peripheral Component Interconnect (PCI) bridge between two buses prefetches read data into a cache. The number of cache lines to prefetch is predicted by a prefetch counter. One prefetch counter is kept for each type of memory-read command: basic memory-read (MR), memory-read-line (MRL) that reads a cache line, and memory-read-multiple (MRM) that reads multiple cache lines. For each type of read command, counters are kept of the number of completed commands, bus-disconnects (indicating under-fetch), and master-discard of data (indicating over-fetch). After a predetermined number of execution of each type of command, the command's prefetch counter is incremented if under-fetching occurred, or decremented if over-fetching occurred, as indicated by the disconnect and discard counters for that type of read command. The command's other counters are reset. Prefetching is optimized for each type of read command. MRM can prefetch more data than MRL or MR.

Abstract: A connection is provided between logical macros to allow prioritization of operations in accordance with an arbitration scheme that distinguishes between operations based on such factors as priority or size of transaction. The invention allows connection of logical macros and prioritizes the appropriate operation for the resources available to optimize data throughput to optimize the utilization of multiple buses. A first arbiter manages data transmissions over a first communication bus. Arriving short or high-priority messages are transmitted over a second communication bus managed by a second arbiter, but only if the target logical macro is not the same as currently targeted by the first arbiter.

Abstract: A circuit for data transfer includes a first buffer operating at a first clock frequency, a plurality of second buffers operating at a second clock frequency, and a selector circuit which receives data at the first clock frequency, and supplies the data to a selected one of the first buffer and the second buffers.

Abstract: It is aimed at improving the efficiency of data transfer processing and the concurrent data processing on a central processing unit. A data transfer device can independently request a bus access right and output an address to a first bus (IBUS) and a second bus (PBUS). It is possible to solve the state of competing for the bus access right between both buses. While the bus access right of one bus is granted for reading or writing, the bus access right of the other bus can be released. When the data transfer device releases the bus access right for the first bus, a central processing unit can process data. In response to one data transfer start request, the bus access right is requested for one bus and the other bus, There is not used a sequence of requesting the bus access right in response to different data transfer requests for respective buses. It is possible to simplify a handshake sequence of a data transfer request and its acknowledgment.

Abstract: A method and apparatus are provided in a computing environment for scheduling access to a resource. The method grants access to the resource by a non-real-time request when the non-real-time request can be completed before the latest possible start time at which a first real-time request must start service to timely complete all actual and anticipated real-time requests, otherwise granting the first real real-time request access to the resource.

Abstract: In a bus control device including an external interface, internal units, a memory interface, and an internal bus, the memory interface monitors the usage pattern of the internal bus, and in a case where the internal unit is not using the internal bus, a priority processing interval for allowing only the external interface to use the internal bus is set, thereby prohibiting the internal units from using the internal bus during the priority processing interval.

Abstract: A system may include two or more agents, one of which may be identified as a default agent. If none of the agents arbitrate for the bus, the default agent may be given a default grant of the bus. If the default agent has information to transfer on the bus, the default agent may take the default grant and my transfer the information without first arbitrating for the bus and winning the arbitration. In one embodiment, the default agent may arbitrate for the bus when it has information to transfer and no default grant is received. The default agent may be an equal participant in arbitration. A fair arbitration scheme may thus be implemented in arbitrations in which there is contention for the bus.

Abstract: A flexible input/output (I/O) interface allows a processing core to communicate high-speed data with a several different types of interfaces including a Direct Memory Access (DMA) interface and a streaming interface. The I/O interface includes a streaming interface for transferring streamed data from the streaming data bus to the core-processing engine, a DMA interface for transferring DMA data from the DMA data bus to the core-processing engine, and an arbiter for coordinating data transfer with the core-processing engine between the streaming interface and DMA interface. The arbiter may operate in a split-bus-mode wherein the arbiter performs the address phase for more than one channel prior to entering into the data phase. The flexible I/O interface may include a common address bus and data bus between the processing engine and the interfaces. Alternatively, a switching fabric may couple separate address and data buss of the interfaces with the processing engine.

Abstract: A method and system to arbitrate between a plurality of resource requests are disclosed. In each arbitration within a current round of arbitration, a winning request is identified based on a priority associated with each requester participating in the arbitration and a set of values stored in a mask register. In response to identifying the winning request, a mask register value corresponding to a requestor of the winning request is updated to disqualify this requestor from further participation in the current round of arbitration. When the current round of arbitration completes, the set of values in the mask register is reset to allow each requestor to participate in the next round of arbitration. The current round of arbitration begins when each requester is qualified to participate in the current round of arbitration and completes when every participating requestor has been disqualified.

Abstract: Apparatus for use in a computer system comprises a bus architecture, a plurality of modules connected to the bus architecture, at least one module being latency tolerant and at least one module being latency intolerant. The bus architecture comprises a primary bus (3) having latency intolerant modules connected thereto, a secondary bus (4) having latency tolerant modules connected thereto, and a primary to secondary bus interface module (5) interconnecting the primary and secondary buses.

Abstract: A method of operating a request FIFO of a system on a chip (SoC) in which a requests in a first position that has been granted and which subsequently receives a retry from the intended target is automatically re-ordered with respect to the other requests below it in the request FIFO. Each issued requests is tagged to either enable or disable a re-order feature. When a request that is tagged as re-order enabled is granted, the FIFO logic monitors the response provided for the request. If the response is a retry, the request is removed from the first position of the request FIFO and the next sequential request is moved into the first position. The removed requests may be re-ordered within the request FIFO or sent back to the initiator. In the former implementation, controller logic reorders the first request within the request FIFO.

Abstract: A method (and structure) in a computer network of controlling the admittance of requests to at least one processing component, includes differentiating the type of received requests based on the message content in each request. Each request is admitted only if the differentiated type meets at least one criterion for admission.

Abstract: A data bus system, capable of distributing devices including first and second data buses capable of transmitting data among a plurality of devices; a register block that stores information on a first bus request signal and a first bus grant signal; a global arbiter that receives the first bus request signal from the register block to output a second bus request signal and receives a second bus grant signal from the register block to output the first bus grant signal. A bilateral bridge that acts as a data transmission path between the first data bus and the second data bus; and a local arbiter exists in each first and second data bus, and receives the second bus request signal from the global arbiter to output the second bus grant signal is disclosed.

Abstract: An interface system capable of providing pre-emptive arbitration among multiple agents comprises an interface including at least a first agent and a second agent which share the interface for transferring data, the second agent having priority over the first agent for access to the interface. A pre-emptive arbiter provides arbitration between the first agent and the second agent when at least one of a first transfer request signal is asserted by the first agent for requesting access to the interface by the first agent and a second transfer request signal is asserted by the second agent for requesting access to the interface by the second agent. The pre-emptive arbiter is capable of synthesizing a transfer completion signal on the interface for preempting access of the first agent to the interface so that access may be granted to the second agent.

Abstract: A digital signal processing system includes multiple processor subsystems, an external input/output port (XPORT), and an XPORT arbiter. The processor subsystems each include a processor core and a DMA controller. The XPORT arbiter arbitrates between the processor cores and between the DMA controllers, and further arbitrates between processor control or DMA control of the XPORT. Upon a request signal from a DMA controller, the XPORT arbiter asserts a hold signal to the processor cores. The processor cores respond by asserting a hold acknowledge signal. A processor core will delay the hold acknowledge signal until through with the XPORT. The arbiter, then asserts a grant signal to the DMA controller requesting access. The arbiter may assert a grant signal to a processor core requesting access. However, the processor core's access will be stalled as long as the hold signal is asserted.

Abstract: An information server with power-aware adaptation that enables power reduction while minimizing the performance impact of power reduction. An information server according to the present techniques includes a transaction prioritizer that determines which of a set of memory subsystems in the information server is to cache a set of data associated with each incoming information access transaction and further includes a power manager that performs a power adaptation in the information server in response to a set of ranks assigned to the memory subsystems. An association of priorities of the incoming information access transactions to appropriately ranked memory subsystems and the judicious selection of memory subsystems for power adaptation enhances the likelihood that higher priority cached data is not lost during power adaptation.

Abstract: The present invention discloses an integrated PCI interface card and the bus system thereof. The integrated PCI interface card of the present invention includes at least two bus masters, a control unit and one multiplexer. The control unit is used in generating the bus request and bus acknowledge signals of the at least two bus masters. The multiplexer is used in selecting an unused address line to be the identification selection signal of one of the at least two bus masters.

Abstract: A computing system having at least one microprocessor and a memory subsystem coupled to the at least one microprocessor. A memory controller is coupled to manage memory transactions between the memory subsystem and the at least one microprocessor. At least one arbitration port is coupled to the memory controller and configured to receive an external arbitration signal.

Abstract: An architecture, method, and apparatus for managing a data buffer (Data Buffer Management DBM). A data buffer within the DBM is an unified linear memory space, and is divided into numbered physical pages with a predetermined page size. A memory map translates logical address spaces for storing/reading DBM transferred data to the physical address spaces. Each packet to be written into DBM is assigned a frame number or frame handler; thereafter, that frame number will be passed by the original owner (a device attached to the data buffer) to different processes for reading out and/or modifying the associated packet or packet data. Frame number assignment is done prior to actual data transfer by request of the data owner. The frame number request is done prior to moving data from the owner's local memory into the DBM's data buffer. Frame number is allocated dynamically by the DBM.

Abstract: A system on a chip has functional blocks accommodated by at least one system bus, and an external bus for accommodating communication with external blocks. A single multi-jurisdictional bus arbiter has programmable rankings for assigning priorities to requests from blocks that are masters for either one of the both buses. Software and methods are also provided for assigning the priorities. The requests are analyzed with respect to which of the buses they require, and then priorities are assigned to maximize bus utilization, with increased speed for a system on a chip. In addition, a multi-jurisdictional multi-channel direct memory access block can be a master block for the system bus or the external bus.

Abstract: A method and apparatus are disclosed for performing dynamic arbitration of memory accesses by a CPU and at least one bus master interface module based on, at least in part, monitoring a CPU throttle control signal and monitoring CPU power and performance states, and making decisions based on the monitored parameters. Bus master memory access break events and memory read and write accesses are also monitored as part of the arbitration process in accordance with certain embodiments of the present invention. An arbitration (ARB) module performs the dynamic arbitration. A CPU throttle control module generates the CPU throttle control signal, indicating when the CPU is idle, and also monitors and outputs the CPU power and performance states. A memory controller (MC) module controls accesses to the memory subsystem based on, at least in part, the dynamic arbitration performed by the dynamic arbitration module.

Abstract: Provided are a method, system, and program for processing operations in a system including a bus, a target device and devices capable of accessing the target device over the bus. The target device receives a transaction request from one of the devices over the bus and determines whether a delayed read request is pending after receiving the transaction request. The target device issues a command to disconnect the device initiating the transaction request from the bus. The device initiating the transaction request is allowed to reconnect to the bus and complete the transaction request after the delayed read request is completed.

Abstract: In one embodiment of the present invention, a bus controller is used in a multi-bus system having first and second buses. The bus controller includes first and second bus interface circuits, a processor interface circuit, and an arbitration logic circuit. The first and second bus interface circuits interface to the first and second buses, respectively. The first bus is accessible to a first processor. The processor interface circuit interfaces to a second processor. The arbitration logic circuit is coupled to the first and second bus interface circuits and the processor interface circuit to arbitrate access requests from the first and second processors.

Abstract: An apparatus for monitoring the state of computer system resources. According to the invention, the apparatus includes bus interface logic and a queue. The bus interface logic is used to interface with a serial bus and parse a bitstream through the serial bus into a command and an address. Also, the apparatus includes bridge logic, an arbitrator and a decoder. The decoder is used to decode the command. If the command represents a predetermined request for access to a resource bus, the decoder passes the predetermined request associated with the address to the queue. Whenever the predetermined request occurs, the arbitrator grants the resource bus to the predetermined request and allows the queue to output the predetermined request as well as the associated address. The bridge logic is provided to transfer data to and from computer system resources according to the predetermined request and the address.

Abstract: A slave device on a data bus has a register that stores a non-queued split master vector containing bits identifying whether a transaction with corresponding master devices have been split. An input gate is responsive to the status of the slave device and to receipt of a command from a master device when the slave device status is busy to set a bit in the non-queued split master vector identifying that the transaction with the corresponding master device is split. An output gate is responsive to a not busy status of the slave device to output the non-queued split master vector to the arbiter to re-arbitrate use of the data bus among the previously-split non-queued master devices.

Abstract: A computer system includes a plurality of memory modules that contain semiconductor memory, such as DIMMs. The system includes a host/data controller that utilizes an XOR engine to store data and parity information in a striped fashion on the plurality of memory modules to create a redundant array of industry standard DIMMs (RAID). The host/data controller also interleaves data on a plurality of channels associated with each of the plurality of memory modules. To optimize memory bandwidth and reduce memory latency, various techniques are implemented in the present RAID system. Present techniques include providing dual memory arbiters, sorting read cycles by chip select or bank address, providing programmable upper and lower boundary registers to facilitate programmable memory mapping, and striping and interleaving memory data to provide a burst length of one.

Abstract: A bus data interface, structure and method for transmitting the data of a PCI bus is disclosed. The bus data interface comprises a high-bit transmitting buffer, a low-bit transmitting buffer, a multiplexer, a strobe generator, and a data distributor. The strobe generator utilizes the bus request signal and bus grant signal to transmit a data strobe signal in response to the PCI clock. According to the rising edge and falling edge of the data strobe signal, the data distributor retrieves data according to the data strobe signal. Further, the invention is compatible with the original PCI bus and allows the PCI bus to transmit data with a dual speed.

Abstract: The invention relates to an operating method for a data bus for several parties with flexible, timed access. According to the method, the parties are synchronized, the bus messages are sent from the parties in a hierarchical sequence and are sent at least in part, only if necessary. A logic element is provided between the parties and the data bus which only gives bus access to each party when said party is allowed to send and for the duration of the send operation.

Abstract: An input port is described having an input policing unit that checks if a virtual lane has a sufficient number of credits to carry an input packet received by the input policing unit. The input port also has a request manager that generates a request for the packet to be switched by a switching core. The input port also has a packet Rx unit that stores the packet into a memory by writing blocks of data into the memory. The input port also has a packet Tx unit that receives a grant in response to the request and reads the packet from the memory in response to the grant by reading the blocks of data. The input port also has a pointer RAM manager that provides addresses for free blocks of data to said packet Rx unit and receives addresses of freed blocks of data from said packet Tx unit.

Abstract: An interface manages the exchange of information between a bus system and a memory during reading, according to a communication protocol. The interface has a protocol-decoding unit, which receives from outside commands and information for managing the reading and generates a wait-code enabling signal, and a wait-state generating unit, which is connected to the protocol-decoding unit and outputs wait codes upon receipt of the wait-code enabling signal. When the memory ends reading, as signaled by switching of a read-state signal, a wait-state disabling circuit generates and supplies an end-of-waiting control signal to the wait-state generating unit, which thus outputs an end-of-waiting code.

Abstract: A shared bypass bus structure for low-latency coherency controller access in a coherent scalable switch. In a coherent scalable switch with multiple coherent interconnect ports, distributed coherency control structures, and a crossbar interface between them, a shared bypass bus permits data transfer between the coherent interconnect ports and the coherency control structures while bypassing the crossbar interface. Some embodiments may comprise scalable switches to support one or more sets of processors with substantially independent snoop or cache coherency paths or arrangements.

Abstract: A four-phase arbitration system employs a master and a slave arbiter. The master arbiter operates to provide ownership of a bus to a first device if a second device, coupled to the slave arbiter is not conducting a transaction. If the second device desires use of the bus, the slave arbiter sends a request to the master arbiter, which asserts an acknowledge signal for as long as the first device has ownership of the bus, and at least as long as a timeout of the first device. The master arbiter de-asserts its acknowledge signal when the first device ceases ownership of the bus. The slave arbiter is responsive to the de-assertion of the acknowledge signal to assert bus ownership to the second device. When the second device transaction is completed, its request signal is de-asserted to the master arbiter, causing the master arbiter to re-assert the acknowledge signal. Failure to receive a de-asserted acknowledge signal causes the slave arbiter to move to the next state.

Abstract: A bus bridge interfaces a primary-side bus with a plurality of secondary-side buses. The primary side bus is a local bus in a system and the secondary-side buses are external buses connected to the system. The bus bridge supports a plurality of kinds of operations one of which is an operation related to a serial bus in accordance with IEEE1394. An access right is given equally to each of the secondary-side buses, when access demands to the primary-side bus are lodged from more than two of the secondary side buses at the same time, by not giving a priority to any one of the secondary side buses.

Abstract: Methods and structure for enhanced bus arbitration providing a hybrid arbitration technique combining priority-based arbitration with round-robin arbitration within a priority level with improved fairness for all devices participating the a round-robin arbitration at a particular priority level. In particular, the invention provides a state retention technique and structure such that the present state of round-robin arbitration at each priority level is saved and restored when a higher priority master device interrupts the round-robin arbitration at a lower level. The restoration of saved state information allows the round-robin arbitration at a lower priority to resume at the saved state to thereby improve fairness of arbitration among devices at a given priority level.

Abstract: A method for transmitting data over a data bus with minimized digital control and data inter-symbol interference. The voltage level on the data bus is not permitted to reach the quiescent negated voltage level set by the bus terminator voltage. Additional time is provided for data detection circuitry to detect a first segment of data transferred over the data bus. A pause time is enabled after the data bus has been idle or paused for a prolonged period. After the first segment of data has been transferred, the method returns to normal operation by pausing for a normal period of time for data detection circuitry to detect subsequent segments of data transferred over the data bus. Additionally, during prolonged synchronous data transfers with unchanged data bits, the data bus is inverted and driven for further regulating the data bus voltage.

Abstract: A data processing configuration with a first circuit configuration (1) that connects a first communication bus (2) with a second communication bus (3). The first circuit configuration (1) is the bus master of the first communication bus (2). Furthermore, a second circuit configuration (4) is connected with the first communication bus (2). By employing a wait signal (11), which is generated in the second circuit configuration (4) and transmitted to the first circuit configuration (1), it is possible to expand read and write access to the first communication bus (2) to any random number of clock cycles.