International Business Machines Corporation

Other

Bruce M Cassidy

Randhir Singh Malik

Donald Wayne Stafford

Andrew Boyce McNeill, Jr

Krishnakumar Rao Surugucchi

Stanley Dyer

Stephen F Newton

Arthur E Graham

Deh C Tao

Shah Mohammad Islam

Patsy A Bowlds

James O Groves, Jr

S M Islam

Alan E Bohnhoff

Robert J Huljak

William S Blocher

Raymond S Hockedy

The invention provides a method, device and system for encoding and decoding data. The method includes receiving information including data units, storing the data units into a memory and encoding the data units by performing a plurality of store and exclusive-or operations on the data units resulting in encoded symbols S, where n is a positive integer.

Encoding and decoding data using store and exclusive or operations

Peripheral Component Interconnect (PCI) device contains Host Messaging Unit (HMU) which is operative to off load host processor and PCI device processor from PCI bus transfer overhead. HMU is configurable to asynchronously retrieve host processor commands from circular buffer, either by using polling or interrupt service techniques. Both host command retrieval methods are operable to remove host processor and PCI device processor from direct PCI bus command transactions, thereby increasing the efficiency of both processors. Interrupt service control of HMU is operative to buffer multiple service requests from PCI device processor, so that a more efficient use of the host processor interrupt service routine is implemented, providing for multiple service requests to be serviced in a single interrupt service request.

Method and apparatus for host messaging unit for peripheral component interconnect busmaster devices

Method and apparatus for host messaging unit for Peripheral Component Interconnect busmaster devices

Structure, method, and computer program for an explicitly tunable device controller. Method supports high-performance I/O without imposing additional overhead during normal input/output operations. Tuning is performed during explicit pre-I/O operation phase. In one embodiment, invention provides a method for tuning device controller operating characteristics to suit attributes of a data stream in which the method comprises: monitoring a data stream and collecting attributes of the monitored data stream; generating performance metrics of the data stream based on the collected attributes and a plurality of different assumed device controller configurations; comparing expected performance of the plurality of different device controller configurations for effectiveness with a future data stream having similar data stream type attributes to the monitored data stream; and selecting device controller characteristics to provide an effective match between the data stream type and the device controller configuration. In one embodiment, the controller configuration is adjusted automatically and dynamically during normal I/O operations to suit the particular input/output operation encountered. Configuration information may be selected for example, from such parameters as data redundancy level, RAID level, number of drives in a RAID array, memory module size, cache line size, direct I/O or cached I/O mode, read-ahead cache enable or read-ahead cache disable, cache line aging, cache size, or combinations thereof. A storage device controller, such as a RAID controller, implementing the inventive method in computer program software or firmware is also provided as are computer system having a host computer coupled to a storage system through the inventive controller.

System, method, and computer program for explicitly tunable I/O device controller

The present invention relates generally to data storage systems having user configurable levels of input/output (&ldquo;I/O&rdquo;) performance and fault tolerance. To provide exceptional performance to read data requests in a RAID data storage subsystem with 100 percent redundancy, the data striping procedure ( ) of the present invention distributes data across disk drives in a data storage subsystem without any backward writes, and thereby provides exception I/O performance with 100 percent data redundancy.

Method and apparatus for distributing data across multiple disk drives

In a data processing system, a redundant array of storage devices is provided for storing data from a host data processing system. When a selected, storage device receives a write command, the selected storage device reads old data from the logical address specified in the write command, and temporarily stores such old data in a buffer. Next, the selected storage device writes new data from the host data processing system to a location specified in the write command. Thereafter, an XOR operation is performed in the selected storage device between the new data and the old data to produce intermediate data. The intermediate data is then transferred to a second storage device within the array. Within the second storage device, old parity data is read from the media in the second storage device and placed in a buffer. Next, an XOR operation is performed in the second storage device between the intermediate data and the old parity data to produce new parity data. Finally, such new parity data is written in the second storage device. Commands for reading data, writing data, performing XOR operations, and transferring data are all generated and executed within the storage devices which comprise the redundant array of storage devices.

Computer storage drive array with command initiation at respective drives

An apparatus for providing identification information to a peripheral device connected to a data processing system via a parallel communications interface cable. The apparatus includes a cable connector for connecting to a cable coupled to the data processing system and a peripheral device connector for connecting to the peripheral device. The cable connector and the peripheral device connector are coupled together to provide communication between the data processing system and the peripheral device. The apparatus also includes means for providing identification information to the connected peripheral device. Such identification information is utilized by the peripheral device to set a device identifier. In one embodiment, device identifiers are set utilizing identification information selected in conjunction with the physical location of the peripheral device. In one embodiment, the apparatus is utilized to connect a SCSI hard disk drive to a data processing system and to provide the SCSI hard disk drive information necessary to set a SCSI device identification number.

Method and apparatus for automatically assigning device identifiers on a

A branch protection circuit is provided to isolate a power network from a faulty load such as an overcurrent condition. The circuit employs a current-sense field effect transistor formed from two power field effect transistors integrated onto the same silicon substrate. The current-sense-FET is provided to detect if the electrical current in the larger FET has exceeded a predetermined threshold level. The circuit does not measure the specific current flowing through the transistors, and the circuitry employed to detect if the threshold current level is exceeded is significantly less complex than circuitry otherwise required to determine a specific current flow through one of the transistors.

Methods and apparatus for isolating a power network from a load during

In critically continuous boost converters used to achieve high power factor and low input current harmonic distortion, a power FET is driven by a pulse generator whose on time is essentially constant over a single line cycle. Off time is terminated when current in the inductor falls to zero and the voltage on the side of the inductor not connected to the input voltage is less that the input voltage. A delay causes turn on to occur at the minimum of the voltage ring to minimize turn on switching losses. At voltages when the input voltage is less than one half of the output voltage part of the on time, turn on occurs with negative current flowing through the FET power switch and the inductor. Part of the turn on time is used to charge the inductor current back to zero before energy can begin to flow back into the output of the converter. A correction circuit is provided which extends the on time as a function of the input and output voltage to avoid dead time around the zero voltage crossover of the sinusoidal input voltage which when rectified provides the input voltage to the converter.

Critically continuous boost converter

Disclosed is a thermal transfer medium which comprises a mixture of a thermosetting polyimide, a thermoplastic polyimide, and graphite. It has a steel support layer and an intermediate layer of silicon dioxide. An outer layer on the steel is the thermal ink. The mixture is applied as a dispersion with a precursor of the thermosetting polyimide. The ribbon may be recoated at the typing station by applying a hot-melt of the ink.

Silicon dioxide intermediate layer in thermal transfer medium

An electrode drive configuration for a resistive ribbon thermal printer utilizes as a feedback a monitored signal representative of an internal ribbon voltage at the print point. A monitoring contact is preferably located on the opposite side of the printhead from the drive signal return contact and the feedback signal is used to cancel the effects voltage drop variations in the common return portion of the drive signal path.

Drive circuit for thermal printer

This specification describes a differential sense amplifier serving balanced sense lines. An imbalance in bias potential on the sense lines holds the sense amplifier in an insensitive state until just before data is to be read on the sense lines. Then a shunting device connected across the sense lines and across the inputs to the differential amplifier is activated to reduce the imbalance and thereby sensitize the differential amplifier. This shunting device is controlled by a feedback path that senses the biasing condition and shuts off the shunting device when the amplifier is in condition to perform the Read cycle.

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Pleasanton, CA, United States of America

Bruce M Cassidy