Patents by Inventor Gregory A. Marlan

Gregory A. Marlan 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).

  • Method and apparatus for performing microcode paging during instruction execution in an instruction processor
    Patent number: 5796972
    Abstract: Method and apparatus for performing microcode paging during instruction execution in an instruction processor. In a preferred embodiment an instruction processor is provided that includes both a microcode ROM and a microcode RAM. The microcode ROM stores the current release of the microcode for the computer system, and the microcode RAM stores microcode patch instructions. During instruction execution, the present invention selects between the output of the microcode ROM and the microcode RAM, depending on whether the instruction requires a patch microcode instruction. If the desired microcode patch instruction is not stored in the microcode RAM, the instruction processor is temporarily interrupted and the desired microcode patch instruction or a group of microcode patch instructions are written, or paged, into the microcode RAM.
    Type: Grant
    Filed: January 14, 1997
    Date of Patent: August 18, 1998
    Assignee: Unisys Corporation
    Inventors: David C. Johnson, Douglas A. Fuller, Kenneth L. Engelbrecht, Gregory A. Marlan, Ronald G. Arnold, Gerald G. Fagerness