Patents by Inventor Nicholas J. Pippenger

Nicholas J. Pippenger has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4750202
    Abstract: The present invention provides a single stage crossbar and a controller for controlling the crossbar that provides a capacity for "wide-sense non-blocking" connection of input signals to outputs that exceeds the number of outputs to which a given input is connected. Thus, the capacity of the crossbar is increased using a smaller number of crosspoints in a single stage than was available in the prior art.In one aspect, the present invention is an apparatus for connecting a signal on one of a plurality of inputs to a non-busy one of a plurality of outputs, comprising a plurality of controllable switches arranged so that each input is connectable to at least an integer q outputs and so that no two inputs share more than an integer c outputs. The invention further comprises a controller for controlling the controllable switches to connect the signal to a non-busy output so that no more than an integer f outputs that are connectable to any input become busy, where f is less than q.
    Type: Grant
    Filed: August 20, 1986
    Date of Patent: June 7, 1988
    Assignee: International Business Machines Corporation
    Inventors: Paul N. Feldman, Joel Friedman, Nicholas J. Pippenger
  • Patent number: 4663620
    Abstract: A method for altering fixed priority conflicts in accessing crossbar switches interconnecting processor-to-processor communications. A fixed priority conflict resolution is substituted for random conflict resolution. There is utilized a method of random restraint for the purpose of restoring the symmetry of access. This is performed by way of a random experiment at each processor using a local threshold parameter and permitting access only when the experimental value exceeds the threshold.
    Type: Grant
    Filed: September 5, 1985
    Date of Patent: May 5, 1987
    Assignee: International Business Machines Corporation
    Inventors: Wolfgang J. Paul, Nicholas J. Pippenger