Patents by Inventor James G. Letwin

James G. Letwin 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: 5608901
    Abstract: A method and system for storing file system state information within sectors of the file system. File system information includes pointers to top-level file system structures, such as free space bitmaps, a bad block list, a directory block band, and a root directory. The file system state information is classified into two groups: frequently-updated information and infrequently-updated information. The two groups are stored on separate sectors in order to minimize write operations performed on the infrequently-updated information and thereby reduce the risk of the infrequently-updated information being corrupted.
    Type: Grant
    Filed: September 1, 1994
    Date of Patent: March 4, 1997
    Assignee: Microsoft Corporation
    Inventor: James G. Letwin
  • Patent number: 5371885
    Abstract: A system and method for allocating contiguous portions of memory to a file. On or more file nodes are provided for allocating memory to one or more files, and the location of these file nodes is maintained. Within these file nodes, the location of one or more runs of contiguous portions of memory are maintained. These contiguous portions of memory are allocated to a file in accordance with the corresponding file node. In one embodiment, the file nodes can be extended in a binary tree structure of additional nodes each storing locations of runs of contiguous portions of memory.
    Type: Grant
    Filed: August 29, 1989
    Date of Patent: December 6, 1994
    Assignee: Microsoft Corporation
    Inventor: James G. Letwin
  • Patent number: 5363487
    Abstract: A method and apparatus interfaces a computer operating system with a storage volume, which is all or part of a data storage media such as a removable floppy-type disk or a hard disk. In a preferred embodiment, the method and apparatus select and associate the appropriate one of a plurality of system drivers with a respective storage volume to permit data communication between the storage volume and the operating system. The method and apparatus permit a single operating system to access a storage medium formatted in accordance with differing file systems, without reprogramming or otherwise altering the operating system. Generally, the operating system identifies which of the plurality of file system drivers is appropriate for reading a particular storage volume and, thereafter, associates the identified file system driver with the particular storage volume.
    Type: Grant
    Filed: August 29, 1989
    Date of Patent: November 8, 1994
    Assignee: Microsoft Corporation
    Inventors: Bryan M. Willman, Mark J. Zbikowski, James G. Letwin, Rajen J. Shah
  • Patent number: 5257370
    Abstract: A method for dynamic caching of data in a disk based operating system. Upon the opening of a file, an access log is created. The access log is updated while accessing the data from the file. Range of access and access time are determined from the access log, and based on the range of access and access time, it is determined whether access of the file was sequential and within a predetermined access time. Based on this determination, a predetermined amount of data from the file is stored in a cache memory when access was sequential and also within the predetermined access time.
    Type: Grant
    Filed: August 29, 1989
    Date of Patent: October 26, 1993
    Assignee: Microsoft Corporation
    Inventor: James G. Letwin