Hewlett-packard Company

Hewlett-packard Development Company, L.P.

Ronald K Arp

Jeffrey J Bain

Curtis C Ballard

Matthias A Lester

David A Eckhardt

James McCarthy

A frequency lock loop has a reloadable N counter that counts cycles of an output frequency during one cycle of a reference frequency. A VCO generates the output frequency. A VCO control drives the VCO based on the count from the counter. The VCO control may include a latch for latching the count at each reference frequency cycle. The VCO control may include a VCO driver, such as a D/A converter or proportional charge pump, connected to a voltage control as input to the VCO. The counter may be reloaded with the integer N value at each cycle of the reference frequency. The counter may decrement from the integer value at each cycle of the output frequency. A lock may occur at N times the reference frequency without regard to phase between output and reference frequencies.

Frequency lock loop having a reloadable counter without rollover

Devices for a Fibre Channel Arbitrated Loop are initially unconfigured, and during the first loop initialization, arbitrate as a soft addressed device. The chosen address is then stored in non-volatile memory. Once an address is stored in non-volatile memory, during subsequent loop initializations, the device arbitrates as a hard address device. Because the address was chosen during a standard Fibre Channel Loop Initialization Process, the risk of future hard address conflicts is greatly reduced. Preferably, however, firm addresses may be erased by operator control, or by system command. Firm addressing provides the fixed address benefits of hard addressing, but substantially reduces the risk of hard address conflicts, while remaining compatible with the ANSI standards for Fibre Channel.

Firm addressing for devices on a fibre channel arbitrated loop

A solution to the problem of I/O card faults caused by spurious RF energy induced by ESD related currents in the vicinity of an aperture in a chassis is to reduce the efficiency of the radiating antenna created by the aperture and decouple any remaining spurious RF energy from any would-be receiving antenna in the I/O card. A conductive boot covers the I/O cable as it emerges from the chassis. The boot is physically attached and AC coupled (as well as probably ohmically connected) to the chassis at one end and tapers down to a small aperture at a distal end to permit egress of the I/O cable. The aperture at the distal end is considerable smaller than the aperture at the chassis, which is no longer visible to ESD induced currents anyway, since its edge has been replaced by the surface of the boot. The smaller aperture is a less efficient antenna at the frequencies of interest and it is now further removed from components that might act as receiving antennae. The intervening length of the conductive boot also acts as a filter to obstruct passage of the reduced amount of spurious RF energy that still does radiate from the small aperture toward the I/O card. The boot may be of metal, or of plastic that has been coated with a suitable conductive paint on its inner surface.

Method and apparatus for alleviating ESD induced EMI radiating from I/O

A system and method is provided in a self-contained high speed repeater/LUN converter that allows for up to fifty-six devices to be connected to a narrow host SCSI bus via a local SCSI bus, where there does not have to be any modification of the devices on the local SCSI bus in terms of the SCSI interface. The host side of the converter supports either a single-ended or a differential SCSI bus. The converter controls all SCSI operations between the host SCSI bus and the local SCSI bus by means of a Corona device and a controller, where Corona controls all of the physical SCSI signals and the controller provides the capability to detect and respond to SCSI error conditions. The controller also selects the operation mode (LUN or repeater), board addresses, host bus type (single-ended or differential) selection, LUN/SCSI address mapping, and data mode (asynchronous, synchronous or fast synchronous) conversion.

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Greeley, CO, United States of America

Ronald K Arp