Method and apparatus for bus arbitration between i

专利名称：Method and apparatus for bus arbitration

between isochronous and non- isochronousdevices

发明人：Richard Allen Kelley,Danny Marvin Neal申请号：US08/566765申请日：19951204公开号：US05758105A公开日：19980526

摘要：An arbiter which allows a normal arbitration algorithm to be implemented forstandard I/O devices, and an isochronous arbitration algorithm to be run for isochronousdevices. Further, the isochronous devices can participate in the normal arbitration schemewhen operating as a standard I/O device. A host bridge interconnects a system bus withan I/O bus, such as the PCI bus. The host bridge includes an arbiter with a normalarbitration algorithm, and, an isochronous arbitration algorithm implemented in eitherlogic circuitry or software. Each I/O device (both standard devices and isochronousdevices) connected to the I/O bus has a bus request line which transmits a request forcontrol of the I/O bus to the arbiter. Depending on the state of the bus request controlsignal, the arbiter can determine which arbitration algorithm is to be utilized. Forexample, a standard device will drive the bus request signal active and hold it in its activestate to indicate a standard bus request. In this case, the arbiter recognizes the standardrequest and runs a standard arbitration cycle. However, an isochronous device will pulsethe bus request line to communicate an isochronous bus request and cause the arbiter torun an isochronous arbitration cycle. It can be seen that an isochronous device can

operate as a standard device by activating its bus request signal and then maintaining it inthe active state.

申请人：INTERNATIONAL BUSINESS MACHINES CORPORATION

代理人：Mark E. McBurney,Thomas E. Tyson,Leslie A. Van Leeuwen

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