US Patent 7324231 Printer expansion method and apparatus

The present invention is a computing system typically but not necessarily used in a printer, which includes a processor for managing operation of a print engine, expansion buses, and bridge devices between expansion buses. A bus bridge is described which can operate in an expansion bus environment. The bus bridge uses a nontransparent PCI bridge in a nonstandard manner to emulate a transparent bus bridge. Processes are included for detecting overall bus topology in the system and for creating configuration cycles on the secondary side of any bridge found.