Abstract: Circuitry and complementary logic are provided to a bus controller, a number of 1:n bus signal distributors, and a number of bus interfaces of an hierarchical serial bus assembly for the bus controller to dynamically detect and manage the interconnection topology of the serial bus elements. The serial bus assembly is used to serially interface a number of isochronous and asynchronous peripherals to the system unit of a computer system. These circuitry and complementary logic support an hierarchical view of the serial bus elements, logically dividing the hierarchy into multiple tiers. This logical view of the serial bus elements is used by the bus controller to detect the presence of interconnected serial bus elements and the functions of the bus agents, i.e.

Abstract: A bus controller, a number of 1:n bus signal distributors, and a number of bus interfaces are provided for form an hierarchical serial bus assembly for serially interfacing a number of isochronous and asynchronous peripherals to the system unit of a computer system. The bus controller, bus signal distributors, and bus interfaces are provided with circuitry and complementary logic for implementing a master/slave model of flow control for serially interfacing the bus agents to each other to conduct data communication transactions. In certain embodiments, these circuitry and complementary logic further conduct connection management transactions employing also the master/slave model of flow control, implement a frame based polling schedule for polling the slave "devices", employ at least two address spaces to conduct the various transactions, support communication packet based transactions, and/or electrically represent data and/or control states.

Abstract: A method and apparatus for dynamically tuning a shared resource's bandwidth utilization, which enables system I/O software to control the length of burst accesses of a shared resource by peripheral components coupled to a peripheral component bus. The present mechanism enables the system I/O software to conduct empirical tests of bandwidth utilization by bus masters accessing the shared resource over the peripheral component bus. Based upon the empirical tests, the system I/O software can tune bandwidth utilization to attain a balance between peripheral component bus performance, and host bus performance.

Abstract: A memory subsystem and method are disclosed in which instruction code read-prefetching is implemented in the memory subsystem itself. A single-line read-prefetch buffer is implemented in the memory subsystem. A memory controller includes an address buffer for read-prefetches, and a memory datapath includes a data buffer for read-prefetches. Smart read-prefetching is used in which only code(instruction) reads are prefetched, taking advantage of the sequentiality of code (instruction) type data as well as the page mode feature of dynamic random access memories.

Abstract: A method of handling processor to processor interrupt requests in a multiprocessing computer bus environment is described. This method allows a multiple-tiered, increasing priority, interrupt request scheme. This method also allows processor to processor directed interrupt requests, processor to one processor of a group of processors interrupt requests, and processor to all processors of a group of processors interrupt requests.

Abstract: A distributed method for arbitrating access to a common bus in a multiple processor environment is described. This method provides for fairness where multiple processors are vying for access to a global memory. An apparatus for arbitrating access to a common bus in a multiple processor environment is also described. This apparatus provides for priority determination of each processor upon system reset and provides for fairness where multiple processors are vying for access to a global memory.

Abstract: A method of transferring data in response to a read command in a computer system having a plurality of processors coupled to an address bus, a command bus and a data bus is described. A first processor generates and sends the read command to read a first data from a second processor. The second processor then determines with which one of (1) the first data and (2) a read response command and the first data it desires to respond to the read command. If the second processor determines to respond with the first data, then it acknowledges receipt of the read command and performs an ordered response in which the command and address buses are released and only the first data is later sent to the first processor via the data bus when available.