Adaptec, Inc.

Charles A Monia

John S Packer

Ebrahim Hashemi

Lawrence J Lamers

Andrew J Roy

The present invention provides a method for assigning addresses to expanded devices in a computer I/O subsystem, which has one or more buses. Each bus has an N-bit data bus for communication. One or more types of expanded devices are provided in the computer I/O subsystem and are coupled to one or more peripheral buses. An expanded address space is defined for the one or more types of expanded devices by partitioning an N-bit data bus into a pair of fields that includes an expanded ID field and an expanded signature field. An address is assigned to each of the expanded devices by assigning an expanded signature to each type of the expanded devices. In addition, an expanded ID is assigned to each expanded device within each type of the expanded devices, wherein more than two bits are asserted in the address.

Methods for assigning addresses to expanded devices in I/O subsystem

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.

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San Jose, CA, United States of America

Charles A Monia