Patents by Inventor Louis B. Bushard
Louis B. Bushard 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).
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Patent number: 7797600Abstract: A method and apparatus for loading a ring of non-scan latches for a logic built-in self-test. A logic built-in self-test value is loaded into a scannable latch from the logic built-in self-test. An override control signal is asserted in response to loading the logic built-in self-test value into the scannable latch. A non-scan latch is forced to load the logic built-in self-test value from the scannable latch in response to asserting the override control signal. Logic paths in the ring of non-scan latches are exercised. The non-scan latch is part of the logical paths. The test results are captured from the logic paths and the test results are compared against expected test results to determine if the logic paths within the ring of non-scan latches are functioning properly.Type: GrantFiled: June 13, 2008Date of Patent: September 14, 2010Assignee: International Business Machines CorporationInventors: Louis B. Bushard, Nathan P. Chelstrom, Naoki Kiryu, David J. Krolak
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Patent number: 7562267Abstract: In a first aspect, a first method is provided that includes the steps of (1) transmitting a first signal representative of a test operation from a test circuit to a memory via a first signal path; (2) transmitting a second signal, synchronized with the first signal, from the test circuit to the memory via a second signal path; and (3) initiating the test operation on the memory in response to the second signal arriving at the memory. Numerous other aspects are provided.Type: GrantFiled: December 28, 2004Date of Patent: July 14, 2009Assignees: International Business Machines Corporation, Kabushiki Kaisha ToshibaInventors: Anthony G. Aipperspach, Louis B. Bushard, Akihiko Fukui, Garrett S. Koch
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Patent number: 7080298Abstract: A method for testing an electronic circuit includes selecting an input signal using a first multiplexer, selecting a signal to be input to the first multiplexer using at least one other multiplexer, and controlling the at least one other multiplexer using a selection signal output from a control circuit.Type: GrantFiled: February 4, 2003Date of Patent: July 18, 2006Assignees: Toshiba America Electronic Components, International Business Machines CorporatonInventors: Naoki Kiryu, Louis B Bushard
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Patent number: 7055077Abstract: Systems and methods for improved performance of built-in-self-tests (BISTs) in integrated circuits, where variability is introduced into the self tests to improve the coverage of the tests. In one embodiment, an LBIST system includes scan chains interposed between levels of functional logic in a circuit under test. An exemplary method includes the steps of, for each of one or more initial scan chains, filling the initial scan chains with data comprising a pseudorandom pattern of bits, determining a number of levels of functional circuitry and corresponding subsequent scan chains through which to propagate the data and propagating the data from the initial scan chains through the determined number of levels of functional circuitry and corresponding subsequent scan chains. The number of levels of circuitry through which data is propagated is varied from one test cycle to another based upon a pseudorandom input signal.Type: GrantFiled: December 23, 2003Date of Patent: May 30, 2006Assignee: Kabushiki Kaisha ToshibaInventors: Naoki Kiryu, Louis B. Bushard
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Patent number: 6909274Abstract: A test apparatus and a method for testing an integrated circuit's data storage device's input/output signal pins for alternating current (AC) defects, by providing an interface that will couple each respective individual test contact, in a subset of said contacts, to a select plurality of the data storage input/output signal pins so that when a selected data string is introduced into the integrated circuit so that each input/output pin on a data storage device in the integrated circuit will be tested in sequence whereby the number of contacts required by the tester can be reduced.Type: GrantFiled: April 21, 2003Date of Patent: June 21, 2005Assignee: International Business Machines CorporationInventors: Frank W. Angelotti, Louis B. Bushard, Matthew S. Grady, Scott A. Strissel
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Publication number: 20040153919Abstract: A test apparatus and a method for testing an integrated circuit's data storage device's input/output signal pins for alternating current (AC) defects, by providing an interface that will couple each respective individual test contact, in a subset of said contacts, to a select plurality of the data storage input/output signal pins so that when a selected data string is introduced into the integrated circuit so that each input/output pin on a data storage device in the integrated circuit will be tested in sequence whereby the number of contacts required by the tester can be reduced.Type: ApplicationFiled: April 21, 2003Publication date: August 5, 2004Inventors: Frank W. Angelotti, Louis B. Bushard, Matthew S. Grady, Scott A. Strissel
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Publication number: 20040153916Abstract: A method for testing an electronic circuit includes selecting an input signal using a first multiplexer, selecting a signal to be input to the first multiplexer using at least one other multiplexer, and controlling the at least one other multiplexer using a selection signal output from a control circuit.Type: ApplicationFiled: February 4, 2003Publication date: August 5, 2004Inventors: Naoki Kiryu, Louis B. Bushard
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Patent number: 6590382Abstract: A test apparatus and a method for testing an integrated circuit's data storage device's input/output signal pins for alternating current (AC) defects, by providing an interface that will couple each respective individual test contact, in a subset of said contacts, to a select plurality of the data storage input/output signal pins so that when a selected data string is introduced into the integrated circuit so that each input/output pin on a data storage device in the integrated circuit will be tested in sequence whereby the number of contacts required by the tester can be reduced.Type: GrantFiled: December 22, 2000Date of Patent: July 8, 2003Assignee: International Business Machines Corp.Inventors: Frank W. Angelotti, Louis B. Bushard, Matthew S. Grady, Scott A. Strissel
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Publication number: 20020079880Abstract: A test apparatus and a method for testing an integrated circuit's data storage device's input/output signal pins for alternating current (AC) defects, by providing an interface that will couple each respective individual test contact, in a subset of said contacts, to a select plurality of the data storage input/output signal pins so that when a selected data string is introduced into the integrated circuit so that each input/output pin on a data storage device in the integrated circuit will be tested in sequence whereby the number of contacts required by the tester can be reduced.Type: ApplicationFiled: December 22, 2000Publication date: June 27, 2002Applicant: International Business Machines CorporationInventors: Frank W. Angelotti, Louis B. Bushard, Matthew S. Grady, Scott A. Strissel
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Patent number: 5819072Abstract: Method for performing critical path timing analysis on a circuit design having different timing constraints for multiple parallel paths. Method includes clearing the state of the circuit design, setting control lines in the circuit design to a selected set of control signals, and identifying blocking nets of the circuit design to be flagged for timing analysis by simulating the circuit design with the selected set of control signals as input signals. Identified blocking points are added to a list which identifies paths in the circuit design to be analyzed. All possible sets of control signals are processed. Timing analysis is then performed on the circuit design using the list as input data. A critical step is the identification of the blocking points. Blocking points are identified for each net input to a gate in the circuit design having an unknown value, and a known value on an output net from the gate for the selected set of control signals.Type: GrantFiled: June 27, 1996Date of Patent: October 6, 1998Assignee: Unisys CorporationInventors: Louis B. Bushard, Peter B. Criswell, Douglas A. Fuller, James E. Rezek, Richard F. Paul
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Patent number: 4873630Abstract: An improved Scientific Processor for use in a data processing system having a general purpose host processor and a High Performance Storage Unit, and under operational control of the host processor is described. The Scientific Processor includes a Vector Processor Module and a Scalar Processor Module, each operable at comparable rates, wherein scalar operands and vector operands can be manipulated in various combinations under program control of an associated host processor, all without requirement of dedicated storage or caching. The Scalar Processor Module includes instruction flow control circuitry, loop control circuitry for controlling nested loops, and addressing circuitry for generating addresses to be referenced in the High Performance Storage Unit. A scalar processor arithmetic logic unit is described for performing scalar manipulations. The Vector Processor Module includes vector control circuitry and vector file storage circuitry together with vector file loading and vector storage circuitry.Type: GrantFiled: July 31, 1985Date of Patent: October 10, 1989Assignee: Unisys CorporationInventors: John T. Rusterholz, Archie E. Lahti, Louis B. Bushard, Larry L. Byers, James R. Hamstra, Charles J. Homan
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Patent number: 4736292Abstract: A series of instructions N, N+1, N+2, etc. are issued by an instruction buffer 14 at a fixed clock rate in a pipelined method to parallel instruction flow path 6 and control word flow path 8, each path including a serial coupled holding register 20, 21, an instruction register 18, 19 and a function register 16, 17. If instruction N is a jump instruction, it and the related control word, when stored in the function registers 16, 17 causes the jump target instruction and the related control word of the jump instruction N to be entered into the holding register 20, 21. If the jump instruction N jump conditions are satisfied, the jump target instruction and related control word are written into the instruction registers 18, 19 and then into the function registers 16, 17 to be executed by the associated system.Type: GrantFiled: December 16, 1985Date of Patent: April 5, 1988Assignee: Unisys CorporationInventors: Michael Danilenko, Larry L. Byers, Louis B. Bushard
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Patent number: 4594680Abstract: A binary division circuit for use in a large data processing system is disclosed which performs division with floating or fixed point numbers. It includes a multiplier unit which is modified to produce the higher precision calculation necessary to the division operation. This modification includes an augmented multiplier circuit which is combined with a quotient correction technique to provide a binary division circuit which produces identical quotients to those obtained by restoring or non-restoring divide techniques in less time than is required by other divide techniques.Type: GrantFiled: May 4, 1983Date of Patent: June 10, 1986Assignee: Sperry CorporationInventors: John R. Schomburg, Louis B. Bushard