At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

James M Grinn

David J Brahm

Edward L Hepler

Edward P Schan, Jr

John M Sullivan

Don R Draper

Kevin A McWethy

Christopher Edmonds

A multiprocessor system comprises a plurality of stations interconnected by a system communication bus and cooperating in the performance of system tasks. Each station includes a plurality of addressable elements interconnected by a station communication bus. All stations are mapped into a common address space, with the elements of each station mapped onto like relative addresses in two subspaces of the address space: a subspace which is shared in common by all stations, and a subspace dedicated to the station whose addresses are the common subspace addresses in combination with a station-identifying address portion. The stations are symmetrical: like elements in all of the stations are mapped onto like relative addresses in their associated subspaces. Addressing within the system is self-referential: a station accesses one of its addressable elements by placing its common subspace address on the station communication bus. Each station's station bus is selectively interfaced to the system bus, and a station accesses an addressable element of another station by placing its dedicated subspace address on the station bus, interfacing its station bus with the system bus, and causing the other station to interface its station bus with the system bus. A station accesses an element of another station passively, without utilizing the intelligence, if any, of the other station to make the access.

Multiprocessor computing system featuring shared global control

Disclosed is a computer system (FIG. 1) that is operable with any multiplexed-address memory (200) within a size range of 2.sup.N to 2.sup.N+R memory locations (211). The system has a memory of 2.sup.S locations selected from the predetermined range, and the memory has S/2 multiplexed address input terminals (231). Address bits forming a memory address, generated for example by a processor (400), are multiplexed by a memory controller (300) onto N/2+R address output terminals (314) in two sets of N/2+R address bits. The address bit sets have at least R/2 bits in common. An address bus (250) transports the multiplexed address bits to the memory. The bus has N/2+R address leads (251) connected to the output terminals of the memory controller. S/2 of those address leads are also connected to the address input terminal of the memory. The remaining address leads are not connected. The memory controller multiplexes the address of any memory within the predetermined range onto its output terminals. Addressing of a different-size memory requires merely connecting the memory to the appropriate address leads of the multiplexed-address bus.

Multiplexed-address interface for addressing memories of various sizes

In a processor system having a central processor and secondary support processor mounted on a backplane board, a separate peripheral interrupt bus is provided for each secondary support processor to give full interrupt priority capability to peripheral devices connected to the support processors. The support processors (110, 120) and certain of the system's peripheral interface circuits (102, 104) are connected to the system's central processor (101) via a primary interrupt bus (105) and other peripheral interface circuits (112, 114, 122) are connected to their associated secondary processors (110, 120) via separate interrupt buses (115, 125) all on the same backplane board. The backplane board is divided into an upper section and a lower section and the primary interrupt bus and the interrupt request and acknowledge terminal pins for all circuit boards are in the lower section. The secondary processor boards and interface circuit boards served by the central processor have interrupt request and acknowledge terminal pins connected to the primary interrupt bus in the lower section. The interrupt request and acknowledge terminal pins for any peripheral interface circuit served by a secondary processor are connected to the associated secondary processor via a secondary interrupt bus formed in the upper section of the backplane and conductors extending between the sections.

Interrupt bus structure

A multiprocessor system comprises a plurality of stations interconnected by a system communication bus and cooperating in the performance of system tasks. Each station includes a plurality of addressable elements interconnected by a station communication bus. All stations are mapped into a common address space, with the elements of each station mapped onto like relative addresses in two subspaces of the address space; a subspace which is shared in common by all stations, and a subspace dedicated to the station whose addresses are the common subspace addresses in combination with a station-identifying address portion. The stations are symmetrical: like elements in all of the stations are mapped onto like relative addresses in their associated subspaces. Addressing within the system is self-referential: a station accesses one of its addressable elements by placing its common subspace address on the station communication bus. Each station's station bus is selectively interfaced to the system bus, and a station accesses an addressable element of another station by placing its dedicated subspace address on the station bus, interfacing its station bus with the system bus, and causing the other station to interface its station bus with the system bus. A station accesses an element of another station passively, without utilizing the intelligence, if any, of the other station to make the access.

In a communication system which includes a plurality of stations interconnected for communications by a first bus, a second station includes a device, such as a processor, and a resource, such as a memory or a peripheral unit, interconnected for communication by a second bus. An interface mechanism connecting the first bus with the second bus allows the device to access the first bus over the second bus, and allows a first station to access the resource via the first and second buses. Deadlock detection circuitry detects cotemporaneous attempts by the device to access the first bus and attempts by the first station to access the resource. Deadlock resolution circuitry responds to deadlock detection by disconnecting the device from the second bus to allow the first station to access the resource, and by reconnecting the device to the second bus when the first station ceases to access the resource. If the device is operating under program control, the deadlock detection and resolution are transparent to the program.

Growing community of inventors

Warrenville, IL, United States of America

James M Grinn