Patents by Inventor Patricia P. McHugh

Patricia P. McHugh 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).

  • Refresh circuit for dynamic memory of a data processor employing a direct memory access controller
    Patent number: 4556952
    Abstract: In a data processing system including a dynamic RAM (14) and a programmable, prioritized direct memory access (DMA) controller (16) having a plurality of channels, the highest priority channel (0) is dedicated to a memory refresh operation. The system clock (P CLK) from the CPU (12) is applied to a divider counter (22) which produces a refresh clock (R CLK) having a period sufficient to generate the minimum number of refresh cycles within the minimum period required to refresh the RAM (14). The refresh clock (R CLK) is used to set a "D-type" latch (24) whose output, in turn, sets the highest priority DMA channel (0) request line (DREQ0), thereby initiating a memory refresh cycle. The latch (24) is cleared by the DMA acknowledge signal (DACK0) indicating the cycle is completed.
    Type: Grant
    Filed: August 12, 1981
    Date of Patent: December 3, 1985
    Assignee: International Business Machines Corporation
    Inventors: James A. Brewer, Lewis C. Eggebrecht, David A. Kummer, Patricia P. McHugh