A computer system including a host CPU, a primary PCI bus coupled to the CPU, and a bus adapter coupled to the primary PCI bus, wherein the host CPU can access peripherals comprised in the bus adapter even when the bus adapter is inoperable. The bus adapter includes a PCI to PCI interface controller...http://www.google.com.hk/patents/US5729767?utm_source=gb-gplus-share專利 US5729767 - System and method for accessing peripheral devices on a non-functional controller 
