International Business Machines Corporation

Forrest Clifton Gray

Mike Conrad Duron

Robert Allan Faust

Ajay Kumar Mahajan

George Henry Ahrens, Jr

Glenn Rueban Miles

Kurt Paul Szabo

Joel Gerard Goodwin

Curtis Ray Genz

Michael Anton Barenys

Kenneth Dean Cummings

Lawrence W Pereira

Donald R Gould

A JTAG bus cross point switching device that is commanded by the same bus which it configures. In a preferred embodiment a JTAG chain includes a cross point switching device that is capable of adding, omitting, or rearranging devices on a JTAG bus. The switching device itself is controlled by commands on the JTAG bus which it configures.

JTAGchain bus switching and configuring device

Commanding a JTAG bus cross point switching device by the same bus which it configures. Adding, omitting, or rearranging devices on a JTAG bus with a cross point switching device that is included in a JTAG chain. Controlling the switching device with commands on the JTAG bus which it configures.

A method and implementing apparatus is provided which include a plurality of perceptible indicia devices which are mounted on an I/O drawer of a computer system server equipment rack. In the exemplary embodiment, the indicia devices include a light-emitting diode in combination with an alphanumeric display device. Various states of a system initialization process are indicated by different combinations of possible states of the LED and the display device such that the sequencing of a system initialization process can be traced by visual inspection of the status of the perceptible indicia devices.

Cues for status information

A multitude of devices coupled to a processor are each given a location code, which is then displayed in proximity to each of the devices. Then, when the processor indicates an error within a particular device, the service person can easily find which device has the error by the displayed location code associated with the device.

System diagnostic location codes

Polling of devices on an inter-IC (I.sup.2 C) is provided. An expansion processor resides on a primary I.sup.2 C bus. The expansion processor is coupled to a plurality of I.sup.2 C sub-buses each of which may host a plurality of I.sup.2 C devices. Data is transferred between the expansion processor and the plurality of I.sup.2 C devices via the corresponding sub-bus according to an I.sup.2 C protocol. Data transfer is in response to a request initiated by a bus master on the primary I.sup.2 C bus. The bus master communicates with a target device residing on one of the sub-buses by addressing the expansion processor. The bus master informs the expansion processor of the target device by sending the expansion processor a number of the sub-bus on which the target device resides, and an address of the target device. A data stream bound for the target device is directed to the expansion processor which then echos it to the target device. Likewise, a data stream bound from the target device to the bus master on the primary I.sup.2 C bus is transmitted to the expansion processor which then echos it to the bus master. Each of the target devices on the sub-bus can be polled to determine if they have failed. Failure of a device only affects operation of its sub-bus.

Polling of failed devices on an I.sup.2 C bus

A character generator for a raster printer which prints in the page mode. Input format data is generated in response to the input print data which defines for each pattern the position of the pattern on the page, the size of the pattern and the location of the pattern in the raster pattern storage. The format data is accessed for all patterns beginning within a predetermined plurality of scan lines and raster data is accessed in response to the format data to store in an output buffer the raster pattern data in the sequence, size and position defined by the format data. The raster pattern data can then be accessed to control a printer to print on a print medium a pattern defined by the input print data.

Growing community of inventors

Austin, TX, United States of America

Forrest Clifton Gray