Patents Assigned to Digital Equipment Corp.
  • Patent number: 6046984
    Abstract: A conservative algorithm for pruning data paths during logic circuit timing verification is disclosed. It uses the correlation between delays on data paths and clock paths in order to prune non-critical data paths during the traversal of the network. Subnetworks are identified in the larger network. Pruning data consisting of the minimum possible delay across all possible paths through the subnetwork, the deskewing clocks, the clock arrival times, and hold times at the synchronizers in the subnetwork are identified the first time each subnetwork is analyzed. In later analysis, the pruning data stored for each subnetwork is used to determine whether a data path can be pruned. A path can be pruned if it is shown to be race-free based on the pruning data. In this way, non-critical paths need only be traced once during timing verification.
    Type: Grant
    Filed: April 11, 1997
    Date of Patent: April 4, 2000
    Assignee: Digital Equipment Corp.
    Inventors: Joel Joseph Grodstein, Nicholas L. Rethman, Nevine Nassif
  • Patent number: 6011679
    Abstract: A technique for controlling a power supply involves receiving a programming signal that indicates a power supply output voltage limit, activating the power supply such that the power supply provides a power supply output voltage according to a power supply threshold voltage, generating a tracking signal that tracks the programming signal, and generating a compare signal according to the tracking signal and an actual value of the power supply output voltage. The technique further involves comparing the compare signal to a protection threshold voltage, maintaining activation of the power supply when the compare signal is less than the protection threshold voltage, and deactivating the power supply when the compare signal is greater than the protection threshold voltage. The protection threshold voltage is independent of the power supply threshold voltage.
    Type: Grant
    Filed: September 30, 1998
    Date of Patent: January 4, 2000
    Assignee: Digital Equipment Corp.
    Inventors: William Ng, Bernhard Schroter
  • Patent number: 5915098
    Abstract: The disclosed system updates client systems regarding changes in a shared display region on a server using compressed graphical display information. The disclosed system compares a first bit map with a second bit map to generate a difference array. The difference array includes indication of each bit in the second bit map having a different value than in the first bit map. The system then transmits the difference array to a client system if at least one bit in the second bit map is different from a corresponding bit in the first bit map. In a further aspect of the disclosed system, the system run length encodes the difference array prior to transmitting if the second bit map is different from the first bit map to generate a run length encoded difference array. The client system generates an updated bit map based on an initial bit map and the difference array. The client system displays the shared region using the updated bit map.
    Type: Grant
    Filed: October 24, 1997
    Date of Patent: June 22, 1999
    Assignee: Digital Equipment Corp.
    Inventors: Ricky Samuel Palmer, Lawrence George Palmer
  • Patent number: 5710724
    Abstract: In a computer system, an instrumented program associated with a first paging table is stored in a memory. The memory also stores an instrumented version of the uninstrumented program associated with a second paging table. The instructions of the uninstrumented and instrumented programs are stored at identical relative addresses. The instrumented programs also includes one word instrumentation points and instrumentation routines to monitor the performance of the computer system. Activating the first paging table causes the uninstrumented program to execute, and activating, in response to a single, the second paging table causes the instrumented program to execute. The instrumentation points cause execution flow to be routed through a gap between word aligned procedures of the program to a routing table, and then instrumentation routines. The gap includes instructions which randomly distributes the execution flow through the routing table.
    Type: Grant
    Filed: April 20, 1995
    Date of Patent: January 20, 1998
    Assignee: Digital Equipment Corp.
    Inventor: Michael Burrows
  • Patent number: 5701427
    Abstract: A computer system comprising one or more information source modules and information display modules interconnected by a communications link. The information source module transmits, and the information display module receives, original information items using a peer-to-peer message transmission protocol. Thereafter, the information source module transmits update information items to the information display modules at one time using a multi-cast information transmission mechanism. In the multi-cast information transmission mechanism, an information display module determines when it has missed an update information message, waits a selected backoff delay time, and transmits a retransmission request for update information messages whose retransmission has not been requested by other information display modules during the backoff delay period.
    Type: Grant
    Filed: September 19, 1989
    Date of Patent: December 23, 1997
    Assignee: Digital Equipment Corp.
    Inventor: Alan Lathrop
  • Patent number: 5669002
    Abstract: A method and apparatus to reduce bus usage and to increase resource locking protocol compatibility within a heterogeneous processing environment. Lock indicators are maintained in stores designated as lock registers and access to a resource is gained by any processor depending upon the status of a lock register associated with that resource. Access to a locked resource is barred to all but the locking processor, and only the processor which has set a lock can use or release that locked resource. A lock register controller controls the contents of the lock registers. A given processor P1-PN is identified by a unique ID vector G1-GN. These vectors are used to indicate both that a resource is locked and to indicate the identity of the locking processor. An unlocked resource is identified by a status vector (G.O slashed.).
    Type: Grant
    Filed: December 8, 1995
    Date of Patent: September 16, 1997
    Assignee: Digital Equipment Corp.
    Inventor: Bruce D. Buch
  • Patent number: 5614444
    Abstract: A method of using additives with silica-based slurries to enhance metal selectivity in polishing metallic materials utilizing a chemical-mechanical polishing (CMP) process. Additives are used with silica-based slurries to passivate a dielectric surface, such as a silicon dioxide (SiO.sub.2) surface, of a semiconductor wafer so that dielectric removal rate is reduced when CMP is applied. The additive is comprised of at least a polar component and an apolar component. The additive interacts with the surface silanol group of the SiO.sub.2 surface to inhibit particles of the silica-based slurry from interacting with hydroxyl molecules of the surface silanol group. By applying a surface passivation layer on the SiO.sub.2 surface, erosion of the SiO.sub.2 surface is reduced. However, the metallic surface is not influenced significantly by the additive, so that the selectivity of metal removal over oxide removal is enhanced.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: March 25, 1997
    Assignees: Sematech, Inc., Intel Corporation, National Semiconductor Corp., Digital Equipment Corp.
    Inventors: Janos Farkas, Rahul Jairath, Matt Stell, Sing-Mo Tzeng
  • Patent number: 5608907
    Abstract: A system for managing an assemblage of entities. The entities interface within the assemblage for control of primary information handling functions and further interface with the system to permit the carrying out of management functions. The system includes management modules adapted to carry out management functions by independently interpreting and executing commands, a kernel including a table of dispatch pointers for directing the commands to the respective modules in which they are to be interpreted and executed, and an enroller for enrolling new modules into the system by adding further pointers to the table.
    Type: Grant
    Filed: April 4, 1995
    Date of Patent: March 4, 1997
    Assignee: Digital Equipment Corp.
    Inventors: Leonard G. Fehskens, Colin Strutt, Arundahati G. Sankar, Steven K. Wong
  • Patent number: 5600833
    Abstract: A system for retrieval of documents in a client-server environment is disclosed. The system provides compatibility between an attribute based document display system and diverse query languages within remote document repositories. The system includes a local process running on a client module, and a remote process running within each document repository. Each remote process is designed for the particular model of computer used for the server. Each remote process executes a System Query Language (SQL) used by a particular database program running on the server. A particular server may have several database programs implemented thereon, and each database program has a dedicated remote process, where the remote process is matched to the particular database program. The local process on the user's workstation launches inquiries in a first format on the network. Each remote process receiving an inquiry translates the received inquiry into the System Query Language required by its server and its database program.
    Type: Grant
    Filed: March 24, 1995
    Date of Patent: February 4, 1997
    Assignee: Digital Equipment Corp.
    Inventors: Jeffrey A. Senn, Andrew D. Brown, Peter Lucas
  • Patent number: 5557796
    Abstract: A system for managing an assemblage of entities. The entities interface within the assemblage for control of primary information handling functions and further interface with the system to permit the carrying out of management functions. The system includes management modules adapted to carry out management functions by independently interpreting and executing commands, a kernel including a table of dispatch pointers for directing the commands to the respective modules in which they are to be interpreted and executed, and an enroller for enrolling new modules into the system by adding further pointers to the table.
    Type: Grant
    Filed: January 21, 1994
    Date of Patent: September 17, 1996
    Assignee: Digital Equipment Corp.
    Inventors: Leonard G. Fehskens, Colin Strutt, Jill F. Callander, Kathy J. Nelson, Matthew J. Guertin, Mark W. Sylor, Kenneth W. Chapman, Robert C. Schuchard, Stanley I. Goldfarb, Dennis O. Rogers, Linsey B. O'Brien, Christine C. Chan-Lizardo, Benjamin M. England, Richard L. Rosenbaum, Ruth E. J. Kohls, David L. Aronson, Allan B. Moore, Robert R. N. Ross, Danny L. Smith, Arundahati G. Sankar, G. Paul Koning, Sheryl F. Namoglu, Mark J. Seger, Timothy M. Dixon, Jeffrey R. Harrow
  • Patent number: 5528513
    Abstract: A scheduler with admissions control in a continuous media file server is presented. The scheduler supports multiple classes of tasks with diverse performance requirements. The scheduler is based on a combination of rate-monotonic and weighted round-robin scheduling schemes. Scheduling is accomplished in a hierarchical manner. Isochronous tasks have the highest priority and are scheduled first followed by real-time and general-purpose tasks. Isochronous tasks run periodically and are invoked by a timer interrupt set for each task. After scheduling the isochronous tasks, the scheduler alternates between the real-time tasks and the general-purpose tasks using a weighted round-robin scheme.
    Type: Grant
    Filed: November 4, 1993
    Date of Patent: June 18, 1996
    Assignee: Digital Equipment Corp.
    Inventors: Lev Vaitzblit, Kadangode K. Ramakrishnan, Percy Tzelnic
  • Patent number: 5499330
    Abstract: A system for displaying documents on a computer controlled display device is disclosed. The system displays documents either in a completely free-form, user controlled configuration or as strands, such that documents in a strand follow a strand path. The strand path is a two dimensional line through a three dimensional display space. The documents displayed on the strand are known as child documents, and each strand also has a parent document. Various constraints defining the strand are associated with the parent document, including a strand function defining the strand path, minimum and maximum separation constraints defining the distance between the child documents on the strand, and an origin constraint defining the positional relationship of the strand path to the screen object of the parent document.
    Type: Grant
    Filed: September 17, 1993
    Date of Patent: March 12, 1996
    Assignee: Digital Equipment Corp.
    Inventors: Peter Lucas, Jeffrey A. Senn
  • Patent number: 5481538
    Abstract: Frame processing apparatus, and a related method for its operation, for use in a station connected to a token ring network, to ensure rapid stripping of frames from the network without reference to source addresses in the frames, and in spite of the possible presence of extraneous no-owner frames on the network. The adverse effects of extraneous no-owner frames are avoided by any of three techniques. First, transmitted information frames are preceded by a start strip delimiter frame and followed by an end strip delimiter frame. The process strips all incoming frames (except tokens and ring initialization frames, which are specially handled), but does not count the stripped frames until the start strip delimiter frame is detected. Therefore, extraneous frames preceding the transmitted information frames will be stripped but not counted, and all of the transmitted frames will be stripped. In another approach, an estimated stripping time is used to terminate stripping.
    Type: Grant
    Filed: April 9, 1992
    Date of Patent: January 2, 1996
    Assignee: Digital Equipment Corp.
    Inventors: Henry S. Yang, K. K. Ramakrishnan, Barry Spinney
  • Patent number: 5450407
    Abstract: A frame having a desired destination address written into the destination address field of the frame is transmitted onto a first communications system, the frame is received by the apparatus, the frame is transmitted by the apparatus onto a second communications system with a second destination address written into the destination address field of the second frame, and also the desired destination address is written into a predetermined field of the second frame along with an indicator. The indicator is capable if being interpreted by a receiving station to mean that the desired destination address is written into the predetermined field of the second frame.
    Type: Grant
    Filed: June 7, 1994
    Date of Patent: September 12, 1995
    Assignee: Digital Equipment Corp.
    Inventors: Radia J. Perlman, William R. Hawe
  • Patent number: 5446575
    Abstract: An apparatus for storing and retrieving data acts as an interface between modules such as data collection devices and data analysis tools. The apparatus provides the capability of maintaining a data standard so the number of translation tools needed to transfer data from one module to another is reduced. The apparatus maintains the data standard by means for storing a configuration data structure having table data structures. The configuration data structure and the table data structure define a data model. The data model is editable. Complex, as well as simple, items may be stored in the table data structure.
    Type: Grant
    Filed: June 28, 1991
    Date of Patent: August 29, 1995
    Assignee: Digital Equipment Corp.
    Inventor: Richard S. Lysakowski, Jr.
  • Patent number: 5434971
    Abstract: An apparatus for storing and retrieving data acts as an interface between modules such as data collection devices and data analysis tools. The apparatus comprises a means for storing a configuration data structure, the configuration data structure having a plurality of data items. The attributes of a data item are a name, a data type, a size, and a mapping parameter. The plurality of data items may contain administrative data, instrument identification data, global sample identification data, detection method data, raw unprocessed data, data peak processing method, data peak processing results, instrument calibration data, multicomponent sample calibration method, results from multicomponent sample calibration, sample sequence data, dimension data, control events for instrument data, reprocessing method data, and reprocessing results data. The apparatus provides the capability of maintaining a data standard so the number of translation tools needed to transfer data from one module to another is reduced.
    Type: Grant
    Filed: June 28, 1991
    Date of Patent: July 18, 1995
    Assignee: Digital Equipment Corp.
    Inventor: Richard S. Lysakowski, Jr.
  • Patent number: 5428615
    Abstract: A connection apparatus for connecting a first communication system with a second communication system and a third communication system. A first frame is received from the first communication system, where the first frame has a multicast address as a destination address, and where the destination address requires the first frame to be transmitted onto the second communication system. The multicast address is translated into a functional address, and the functional address is written into a second frame transmitted onto the second communication system. The second frame is received and is transmitted onto a third communication system, and the functional address is translated into a multicast address for the third communication system, and the multicast address is written into a destination field of the frame as it is transmitted onto the third communication system. The second communication system may be a token ring system based upon an IEEE 802.
    Type: Grant
    Filed: July 21, 1994
    Date of Patent: June 27, 1995
    Assignee: Digital Equipment Corp.
    Inventors: Floyd J. Backes, William R. Hawe, G. Paul Koning, David J. Mitton, Radia J. Perlman
  • Patent number: 5414700
    Abstract: A technique for establishing and maintaining full duplex communication between two stations connected to a token ring network, without physically reconfiguring the station connections or otherwise disturbing the network. Each station continually performs a two node test to ascertain whether there are only two active stations on the network, and updates a two node flag that indicates whether or only two active stations are present. The two node test uses both upstream neighbor and downstream neighbor addresses to update the two node flag, and requires validation of either one of these addresses if the other one of them appears to have changed since the previous observation. A concurrently running full duplex control process uses the two node flag and other conditions to decide whether to initiate or continue transition to full duplex mode.
    Type: Grant
    Filed: April 12, 1994
    Date of Patent: May 9, 1995
    Assignee: Digital Equipment Corp.
    Inventors: Henry S. Yang, Barry A. Spinney, William R. Hawe, Luc A. Pariseau
  • Patent number: 5404353
    Abstract: A technique for controlling access to a bridge connected to at least two networks, such that network collisions are reduced, transmit live-lock conditions are eliminated, and buffer memory requirements are minimized. For at least one target network of the two networks, two dynamic lists are maintained, to keep track of data packets received from the target network and not yet forwarded, and to keep track of data packets stored for forwarding to the target network, but not yet forwarded. The target network uses a half-duplex medium and a CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol. The invention operates by dynamically adjusting an inter packet gap (IPG) betweens data packets forwarded to the target network, such that stations on the target network are, under selected conditions, given an extended opportunity to transmit.
    Type: Grant
    Filed: May 12, 1994
    Date of Patent: April 4, 1995
    Assignee: Digital Equipment Corp.
    Inventors: Siman-Tov Ben-Michael, Philip P. Lozowick, Henry S. Yang
  • Patent number: D395297
    Type: Grant
    Filed: September 17, 1993
    Date of Patent: June 16, 1998
    Assignee: Digital Equipment Corp.
    Inventors: Hugo T. Cheng, Joseph M. Ballay, Peter Lucas