Patents Represented by Attorney Ronald E. Myrick
  • Patent number: 5235644
    Abstract: A decryption method, and associated cryptographic processor, for performing in-line decryption of information frames received from a communication network through a first in-line processing stage. As an information packet is streamed into the cryptographic processor, a determination is made to an acceptable level of probability whether the packet contains data that should be decrypted. The decision whether or not decrypt is made by analyzing the incoming packet header, recognizing a limited number of packet formats, and further parsing the packet to locate any encrypted data and to make sure that the packet is not a segment of a larger message. Falsely decrypted packets are looped back through the cryptographic processor, to regenerate the data that was falsely decrypted. Decryption and encryption are performed in such a manner that a false decryption is completely reversible without loss of data.
    Type: Grant
    Filed: June 29, 1990
    Date of Patent: August 10, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Amar Gupta, Butler W. Lampson, William R. Hawe, Joseph J. Tardo, Charles W. Kaufman, Mark F. Kempf, Morrie Gasser, B. J. Herbison
  • Patent number: 5233616
    Abstract: This invention relates to a write-back cache which is protected with parity and error correction coding ("ECC"). The parity and ECC codes are generated by a memory interface when data is transferred by main memory to the central processing unit ("CPU") associated with the cache. Thus, all data originating in main memory will be parity and ECC encoded when it passes through the memory interface, and the data, and its related parity information and ECC codes will be stored in the cache. On the other hand, data which is taken from the cache and modified by the CPU during its processing operations is also transferred to the memory interface for ECC encoding. Thus, all data modified by the CPU is also protected, and the modified data, and its related parity information and ECC codes are also stored in the cache.
    Type: Grant
    Filed: October 1, 1990
    Date of Patent: August 3, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Michael A. Callander
  • Patent number: 5220271
    Abstract: The disclosed invention regulates the voltage of an output terminal of a multiple output power supply. It operates by diverting current from one output terminal to another output terminal. The invention is less expensive than other alternatives, and has performance advantages over comparably priced alternatives. It may be used in various configurations to maintain an output voltage below a limit, above a limit, or within a range. Additional configurations may be used to regulate the voltages of multiple output terminals.
    Type: Grant
    Filed: March 17, 1992
    Date of Patent: June 15, 1993
    Assignee: Digital Equipment Corporation
    Inventor: John J. Palczynski, Jr.
  • Patent number: 5218557
    Abstract: A new system design tool receives a design representation from a designer, simulates it and compares the simulated operation of the design representation with the desired operation as provided by the operator and identifies causes of discrepancies therebetween. The redesign component performs redesign operations on the design representation in response to the discrepancies. The redesign component includes a plurality of redesign modules each including a redesign solution selection module which receives the identification of causes of discrepancies and the design representation and identifies a redesign solution in response thereto. Each redesign module, in turn, includes at least one redesign operator module which includes a plurality of redesign operators controlled by a redesign control module. The redesign operators each perform a redesign operation in connection with the design representation.
    Type: Grant
    Filed: October 21, 1991
    Date of Patent: June 8, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Evangelos Simoudis
  • Patent number: 5212776
    Abstract: A processor in a computer system is connected, together with one or more control units of peripheral apparatus, to the main memory via a main bus. For a very fast processor the storage capacity of the main memory should be so high that the full physical address can no longer be transported via the main bus in one operation. In that case an additional communication line is provided between the processor and the main memory. In order to enable peripheral apparatus to access the entire main memory anyway, a second memory management unit is connected between the main bus and the main memory.
    Type: Grant
    Filed: April 3, 1989
    Date of Patent: May 18, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Frederik Zandveld, J. A. G. M. Kindervater
  • Patent number: 5212650
    Abstract: A procedure is described for the synthesis and transformation of a logic circuit design, provided by the designers, into a database capable of being used to fabricate the actual circuit. The procedure involves the use of model instances which represent the use of circuit components. The original model instances can be associated with groups of rules that determine resulting configurations of generally different model instances or groups of model instances. The rules are tested and, in the presence of a `true` result, a new model instance (or model instances) can replace one or more original model instances in the data base. The rules associated with a model type (or definition) are rules derived by a design model engineer and can include coupled model instances. The rules can be associated with model definitions, as well as model instances.
    Type: Grant
    Filed: August 3, 1989
    Date of Patent: May 18, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Donald F. Hooper, Snehamay Kundu
  • Patent number: 5210837
    Abstract: A method for translating an initial program flow representation of a computer program into a modified program flow representation examines paths in the initial program flow representation, selects for replication nodes which have multiple predecessor nodes and a single successor node which have never been path search exit nodes and which are neither loop members of successors of loop members. Some of those selected nodes are then replicated and replace the nodes that were replicated. The program flow representation can then be reduced by combining nodes which have a predetermined relationship. This resulting flow representation is well suited for translation into a desired computer language.
    Type: Grant
    Filed: June 15, 1990
    Date of Patent: May 11, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Cheryl A. Wiecek
  • Patent number: 5208768
    Abstract: A new expert system performs a redesign in connection with an original design. The expert system comprises a discrepancy determination component that identifies a discrepancy between operation of the original design and a desired operation. A redesign component including at least one redesign module associated with a discrepancy generates a redesign in response to the original design and the identified discrepancy. Finally, a redesign generation component generates a redesign module in response to a previously-identified discrepancy and design, the redesign module thereafter being used by the redesign component.
    Type: Grant
    Filed: July 30, 1991
    Date of Patent: May 4, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Evangelos Simoudis
  • Patent number: 5208518
    Abstract: A process and a circuit control the rotational speed of a direct current motor. In particular, the motor may be used to drive magnetic or optical data carriers. The motor is fed with a motor current by a switching device for commutation wherein the motor current induces a magnetic flux which generates the motor torque. The process and circuit increase the motor voltage applied to the motor in the startup or braking phase to a value above the supply voltage. Further, the process and circuit reduce the motor voltage during the commutation phase so that commutation switching may occur in a reduced-current condition.
    Type: Grant
    Filed: November 15, 1991
    Date of Patent: May 4, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Hans Grapenthin, Horst Haug
  • Patent number: 5206713
    Abstract: A mounting for a semiconductor chip is composed substantially of polysilicon materials and incorporates integral heat dissipating elements into its design. The mounting can be cast from molten polysilicon or machined from a block of solid polysilicon depending on the shape and complexity of design of the mounting and heat dissipating elements. Polysilicon has excellent heat transfer properties and is closely matched to silicon in its coefficient of thermal expansion thereby reducing mechanical stress between the mounting and the chip. The semiconductor chip is attached directly to the polysilicon mounting establishing a direct thermal pathway between the heat generating chip and the heatsink elements of the mounting. The configuration of using direct attachment to a polysilicon mounting creates a thermally efficient package with greatly enhanced heat transfer capabilities and reduced mechanical stress. The mounting can accommodate both single and multi-chip applications in a variety of arrangements.
    Type: Grant
    Filed: June 28, 1991
    Date of Patent: April 27, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Michael L. McGeary
  • Patent number: 5204496
    Abstract: An EMI shielding gasket made of springy electrically conductive material. The gasket includes a pair of generally parallel laterally spaced apart U-shaped channel members each with its channel entrance facing away from the other member. A pair of ends oriented transversely of the U-shaped channel members connect the members together at their end regions. The ends are resiliently deformable to allow the U-shaped channel members to be moved more closely together to facilitate mounting the gasket.
    Type: Grant
    Filed: April 1, 1992
    Date of Patent: April 20, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Steven G. Boulay, Michael L. Joseph, Henry A. Rettstadt
  • Patent number: 5204963
    Abstract: A method and apparatus for a software actuable backup power controller for selectively controlling power to a volatile random access cache memory. If memory does not contain any data that needs to be retained during a primary power failure the controller isolates memory from the backup power supply during the power failure. Only when the memory contains data to be retained during a power failure will memory be treated as non-volatile and is the backup power supply connected to memory on primary power failure. By selectively enabling the backup power supply with software commands from the computer, a suitable cache memory can be constructed with a compact non-rechargeable battery.
    Type: Grant
    Filed: December 7, 1990
    Date of Patent: April 20, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Eric S. Noya, Randy M. Arnott
  • Patent number: 5202880
    Abstract: A low-profile magneto-optical media for double sided recording of information. The media comprises a single polycarbonate substrate having a relief in the form of tracking grooves or sampled-servo pits on each side surface thereof. Formed on each relief surface are thin-film active layers including a reflective layer, a transparent dielectric layer, a magneto-optical recording layer, and a transparent protective layer. The reflective layer is preferably formed of aluminum alloy. The dielectric layer is preferably formed of aluminum nitride or silicon nitride. The recording layer is formed of an amorphous vertically oriented magnetic material, preferably a rare-earth transition-metal alloy, for example, Tb-Fe-Co. The protective outer layer is formed of a transparent anti-corrosive material specifically compatibly with an air-bearing, low-flying, read/write head, preferably silicon nitride.
    Type: Grant
    Filed: March 6, 1992
    Date of Patent: April 13, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Neville K. Lee, Brian Tan
  • Patent number: 5199743
    Abstract: A folder is described which holds and protects media, such as multiple disks, during and subsequent to shipping. An insert is provided that may be assembled with the folder and which increases the disk storage capacity of the folder assembly. A pocket is also provided to hold documentation associated with the disks.
    Type: Grant
    Filed: February 10, 1992
    Date of Patent: April 6, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Alexander B. Rosinski, III
  • Patent number: 5199168
    Abstract: A method of forming a tachometer roller for a tape drive assembly for detecting the speed of a tape moving along a reference axis when the tape is in contact with the roller. The roller includes a cylinder extending in a longitudinal axis and adapted to be fixed in a tape drive assembly for rotation along the reference axis. The periphery of the cylinder defines an air vent groove running obliquely to the longitudinal axis for venting of air captured between the periphery and the tape. The vent groove terminates in respective circumferential grooves formed in respective edge portions of the roller. The vent groove is formed from a single plunge cut of a tool starting at a first circumferential groove and terminating at the other circumferential groove.
    Type: Grant
    Filed: October 3, 1991
    Date of Patent: April 6, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Keith L. Daly
  • Patent number: 5194696
    Abstract: An gasket is disclosed for environmentally sealing an enclosure of a disk storage device. The gasket, which is disposed between a base and cover portion of the enclosure is designed to accommodate a flat flexible wiring cable (flexcircuit) protruding therethrough.The gasket includes a compressible seal portion attached to the inner edge of a rigid plastic frame. The thickness of the seal is made slightly greater than the thickness of the frame. The width of the seal is substantially smaller than the width of the frame. A relief is formed on one surface of the gasket to receive the flexcircuit. The relief includes a groove extending across the width of the gasket. The groove has a depth essentially the same as the thickness of the flexcircuit, and a width slight larger than the width of the flexcircuit.Two ridges are formed across the entire width of the compressible seal portion of the gasket in the area immediately adjacent to the groove.
    Type: Grant
    Filed: September 27, 1991
    Date of Patent: March 16, 1993
    Assignee: Digital Equipment Corporation
    Inventor: John D. Read
  • Patent number: 5192893
    Abstract: The disclosed invention relates to a video display system having a device for shielding electromagnetic radiation emitted from electrical wires which connect a video amplifier to a cathode ray tube. The device uses inexpensive unshielded wires which are recessed within a conductive shielding enclosure. The wires are connected to the cathode ray tube by a socket which is positioned at an access opening in the shielding enclosure. The invention further relates to a device for mounting a shielding enclosure to a base using tabs on the enclosure which are captured in an interference fit between the surface of the base and brackets coupled to the base.
    Type: Grant
    Filed: April 6, 1992
    Date of Patent: March 9, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Daniel J. J. Velasco, Dennis C. Robinson, Jeffrey P. Copeland, Ricardo L. Fernandez
  • Patent number: 5192214
    Abstract: In the manufacture of flat-panel video displays, an assembler must align long rows of closely-spaced electrical signal contacts on a planar electroluminescent panel with mating signal contacts on a flex circuit prior to clamping the panel and flex circuit together. The disclosed technique employs electrically conductive alignment contacts on both surfaces. The alignment contacts are formed via the same process that forms the signal contacts. The alignment contacts are connected to ohmmeters to form circuits that an assembler monitors to determine proper alignment of the surfaces. The use of electrical rather than visual alignment checking makes assembly easy and error-resistant.
    Type: Grant
    Filed: February 10, 1992
    Date of Patent: March 9, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Victor M. Samarov, George A. Doumani
  • Patent number: D334733
    Type: Grant
    Filed: April 8, 1991
    Date of Patent: April 13, 1993
    Assignee: Digital Equipment Corporation
    Inventors: Stuart K. Morgan, Margaret L. Hetfield
  • Patent number: D335501
    Type: Grant
    Filed: January 9, 1991
    Date of Patent: May 11, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Robert T. Faranda