Patent ID: 7020726

Claim:
An apparatus for selecting bus-width formats, comprising: a first bus controller configured to provide receive a first bus-width control signal to select a first bus-width wherein said first bus controller is compliant with Peripheral Computer Interconnect Bus Specifications version 2.2 as regards said first bus-width control signal; and a bus controller extension circuit configured to force the first bus-width control signal to a predetermined level when the first bus controller is applied to a bus with a second bus controller that is incompatible with the first bus-width wherein the second bus controller and the bus adhere to Peripheral Computer Interconnect Bus standards that pre-date the Peripheral Computer Interconnect Bus Specifications version 2.2 and do not adhere to Peripheral Computer Interconnect Bus Specifications version 2.2 as regards said first bus-width control signal wherein the second bus controller does not adhere in that it provides no bus-width control signal and wherein the bus adheres to Peripheral Computer Interconnect Bus Specifications that pre-date version 2.2 and hence does not include a bus-width control signal.