Abstract: An expander device and method for isolating bus segments from one another in an I/O subsystem. The expander device is arranged to couple the bus segments for communication in the I/O subsystem. The expander device includes a first I/O interface circuit, a second I/O interface circuit, and an expander controller. The first I/O interface circuit is configured to be coupled to a first bus segment and is adapted to interface input and output communication signals with the first bus segment. The second I/O interface circuit is configured to be coupled to a second bus segment and is adapted to interface the input and output communication signals with the second bus segment. The expander controller is coupled to communicate the input and output communication signals between the first and second I/O interface circuits. The expander controller is further arranged to control communication between the bus segments and includes a segment controller adapted to generate a first signal.

Abstract: Expander device and method for resetting bus segments in I/O subsystem to clear bus hang in an I/O subsystem having a plurality of bus segments. Each bus segment in the I/O subsystem includes a set of devices and a bus that is coupled to the set of devices. In addition, the I/O subsystem includes at least one expander, each expander being arranged to couple a pair of buses for propagating communication signals. A reset signal is asserted on a first bus segment. In response to the reset signal, each expander coupled to the first bus segment and each device in the first bus segment reset themselves. Additionally, each expander coupled to the first bus segment isolates the reset signal such that the reset signal is not propagated to the other bus segments. For each expander coupled to the first bus segment, all communication signals are isolated such that each expander prevents propagation of the communication signals between the first bus and other bus.

Abstract: The present invention provides methods for addressing an extended number of peripheral devices over a bus. A bus having an N-bit datapath is provided in a computer system. An extended address space is defined for a set of extended peripheral devices by assigning a bus ID to each extended peripheral device. Each bus ID includes a group ID and a group member ID. Each group ID and group member ID also indicates a priority of said associated device. One or more peripheral devices arbitrate for the bus. In this process, a peripheral device having the highest priority group ID and the highest priority group member ID among the arbitrating devices wins the arbitration. After arbitration, the winning device selects, for transferring data, a device by placing on the bus the bus IDs of the selecting and selected devices.

Abstract: A method and system are provided for determining maximum data throughput between a host adapter and one or more target devices coupled to the host adapter through a bus. A first set of device identifying data is obtained from a target device over the bus. Then, a maximum data throughput rate is negotiated between the host adapter and the target device over the bus. Next, a second set of device identifying data is obtained from the target device over the bus at the negotiated maximum data throughput rate. Read and write tests are performed to determine the maximum data throughput rate. When the first and second sets of device identifying data are identical, the host adapter and the target device are operated over the bus at the negotiated maximum data throughput rate.