Digital Equipment Corporation

Frank M Nemeth

Mark F Amberg

Stephen J Sicola

Bruce A Sardeson

William K Miller

Dwayne Howard Swanson

Mike Hare

Brian Schow

In a modular tower building block system for containing computing system devices, an I/O bus is incorporated into the modular blocks of the building block system by using a printed circuit board to carry the I/O bus in each modular block. The printed circuit board is mounted and positioned in each modular block to electrically connect with a printed circuit board in a next adjacent modular block when two modular blocks are stacked on each other. Also, there are a plurality of I/O buses on the printed circuit boards and only one I/O bus is distributed from each modular block. The printed circuit board is precisely located in each modular block at a predetermined position. Alignment pins and receivers provide alignment between stacked modular blocks to precisely position one modular block to the other modular block. This also aligns electrical connectors on the printed circuit boards of the stacked blocks so that the connectors on the printed circuit boards from two blocks mate when the two blocks are stacked.

Input/output bus system in a tower building block system

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. A conflict in responses indicates a SCSI device is installed at the low ID and a narrow SCSI device is installed at the high ID of the test pair. To detect a future conflict between a narrow SCSI device at a high ID and a SCSI device installed in the future at an unused low ID, both the low ID and the high ID are called. No response to the high ID call in combination with a response to the low ID call indicates a narrow SCSI device is installed at the high ID and the narrow SCSI device would conflict in the future with a SCSI device subsequently installed at the unused low ID.

Detection of SCSI devices at illegal locations

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.

System for reconfiguring addresses of SCSI devices via a device address

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Colorado Springs, CO, United States of America

Frank M Nemeth