Abstract: In a SCSI subsystem having mixed wide and narrow SCSI devices installed, a method and apparatus is provided for detecting a narrow SCSI device illegally installed at a slot assigned to a wide SCSI device. To detect the narrow SCSI device installed at an illegal location, high ID and low ID SCSI bus address pairs are set as test pairs for the SCSI subsystem. The low ID is the alias of the high ID if a narrow SCSI device is installed at the high ID slot. To detect a conflict with a controller ID, a non-responsive ID bus address corresponding to a slot known to be unused is called. A response to this call indicates a narrow SCSI device is installed at the high ID of the test pair and the narrow SCSI device at the high ID has configured to an alias bus address matching the controller ID. To detect a present conflict between SCSI devices, the low ID bus address in the test pair is called.

Abstract: A system for assigning addresses to devices interconnected on a small computer system interface (SCSI) bus. A device address bus independent of the SCSI bus interconnects address assignable devices on the SCSI bus. The devices, each of which has a SCSI ID by which it is identified and being set with default bus address information representing the SCSI ID, are connected to one or more address lines on the device address bus. A system user can selectively reconfigure the bus addresses of the devices by utilizing a personality unit to override one or more bits of the bus address information. The personality unit includes a bus address selector, coupled to the device address bus, which selects address lines according to user input. The selecting of an address line effects a change in the default bus address information associated with the one or more devices connected to the selected address line.