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Robert C Gulick, Mitchell A Bauman, Douglas E Morrissey: Message flow protocol for avoiding deadlocks. Unisys Corporation, Steven B Samuels, Mark T Starr, Rocco L Adornato, January 11, 2000: US06014709 (40 worldwide citation)

System and method for controlling the flow of messages in a computer system to minimize congestion and prevent deadlocks in communications. The computer system includes a main memory, a plurality of crossbar switches, a plurality of third level caches, and a plurality of input/output modules, which ...


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Douglas E Morrissey, Edward T Cavanagh Jr, Kin H Ng: I/O subsystem with header and error detection code generation and checking. Unisys Corporation, Ratner & Prestia, October 31, 1995: US05463762 (40 worldwide citation)

Apparatus is provided for use in an Input/Output (I/O) subsystem. The I/O subsystem is coupled to a serial data transfer medium that transmits data from a sender to a recipient. The I/O subsystem processes a frame comprising user defined data and frame control data. The frame is received over the se ...


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Mitchell A Bauman, Arthur J Nilson, Douglas E Morrissey: Computer system including plural caches and utilizing access history or patterns to determine data ownership for efficient handling of software locks. Unisys Corporation, Steven B Samuels, Mark T Sterne Kessler Goldstein & Fox P L L C Starr, April 18, 2000: US06052760 (27 worldwide citation)

A system and method for enabling a multiprocessor system employing a memory hierarchy to identify data units or locations being used as software locks. The memory hierarchy comprises a main memory having a plurality of data units, a plurality of caches that operate independently of each other, and a ...


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Douglas E Morrissey, Edward T Cavanagh Jr, Gene T Wieder, Kin H Ng, William E Oldham: Serial I/O channel having dependent and synchronous sources of control data and user defined data. Unisys Corporation, John B Sowell Esq, Mark T Starr Esq, John F O Rourke Esq, November 3, 1998: US05832310 (24 worldwide citation)

Apparatus is provided for transferring user defined data from a parallel storage medium to a serial link driver in an I/O channel subsystem of a processor or I/O device controller. The serial link driver transmits a frame of user defined data over a serial data transfer medium. A data buffer receive ...


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Joseph S Schibinger, Douglas E Morrissey: System and method for avoiding deadlocks utilizing split lock operations to provide exclusive access to memory during non-atomic operations. Unisys Corporation, Steven B Sterne Kessler Goldstein & Fox P L LC Samuels, Mark T Starr, July 18, 2000: US06092156 (22 worldwide citation)

A system and method for avoiding deadlocks when performing non-atomic operations on data in a shared memory accessed by multiple processors that sends messages to implement a split lock. Via the messages, the requesting processor is granted exclusive access to the shared memory so that no other proc ...


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Mitchell A Bauman, Eugene A Rodi, Douglas E Morrissey: Directory-based cache coherency system supporting multiple instruction processor and input/output caches. Unisys Corporation, Beth L McMahon, Charles A Johnson, Mark T Starr, July 1, 2003: US06587931 (18 worldwide citation)

A directory-based cache coherency system is disclosed for use in a data processing system having multiple Instruction Processors (IP) and multiple Input/Output (I/O) units coupled through a shared main memory. The system includes one or more IP cache memories, each coupled to one or more IPs and to ...


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Douglas E Morrissey, Edward T Cavanagh Jr, Gene T Wieder, Kin H Ng, William E Oldham: Serial I/O channel having independent and asynchronous facilities with sequence recognition, frame recognition, and frame receiving mechanism for receiving control and user defined data. Unisys Corporation, Ratner & Prestia, September 3, 1996: US05553302 (17 worldwide citation)

An Input/Output (I/O) subsystem is provided for transferring frames containing frame control data from a serial data transfer medium to a parallel storage medium. The subsystem includes independent components for processing different portions of the received character stream. The subsystem includes ...


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Mitchell A Bauman, Joseph S Schibinger, Donald R Kalvestrand, Douglas E Morrissey: System and method for providing speculative arbitration for transferring data. Unisys Corporation, Steven B Samuels, Mark T Sterne Kessler Goldstein & Fox P L L C Starr, April 11, 2000: US06049845 (15 worldwide citation)

A system and method for optimizing the amount of time it takes for a requestor (device) to receive data from a memory storage unit in a multi-requestor bus environment. The present invention provides a unidirectional response signal, referred to as an early warning signal, sent from a memory storage ...


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Mitchell A Bauman, Eugene A Rodi, Douglas E Morrissey: Directory based cache coherency system supporting multiple instruction processor and input/output caches. Unisys Corporation, Michael B Atlass, Charles A Johnson, Mark T Starr, August 20, 2002: US06438659 (13 worldwide citation)

A directory-based cache coherency system is disclosed for use in a data processing system having multiple Instruction Processors (IP) and multiple Input/Output (I/0) units coupled through a shared main memory. The system includes one or more IP cache memories, each coupled to one or more IPs and to ...