International Business Machines Corporation

Michael Alan Veal

Robert Frank Maddock

Robert Bruce Nicholson

Paul Nicholas Cashman

Reginald Beer

A method and apparatus for improving performance of a loop network, in particular a Fiber Channel Arbitrated Loop. The loop network has two loops and a plurality of dual-ported devices each with one port on each loop. The method includes selectively bypassing redundant ports on the loops by a first command means in the form of a Fiber Channel Arbitrated Loop command to balance port accesses and to reduce the loop overhead by reducing the number of ports in each loop. In the event of a fault, bypassing the port of a device by a second command means in the form of a non Fiber Channel Arbitrated Loop command and enabling all the bypassed redundant ports with a single command to all ports using the first command means. The first command means does not enable the port bypassed by the second command means.

Method and apparatus for improving performance of a loop network

A load driver circuit is provided with an improved common mode rejection ratio. A voltage regulator () regulates a ground voltage () in response to variations in input voltage () and provides a regulated ground voltage. An amplifier stage has a first amplifier () with sense inputs coupled to receive voltage signals from a sense resistor () of the load driver circuit. The first amplifier () is powered by the input voltage () and the regulated ground voltage respectively, such that the common mode rejection ratio of the load driver circuit is reduced. In this way an arrangement, circuit and method is provided in which CMRR is drastically improved, rendering a single (or first) stage of a current sensing load driver circuit substantially immune to common mode noise.

Amplifier arrangement, circuit and method with improved common mode rejection ratio

A method is provided for remotely controlling power to electronic devices. Each device includes two or more ports for receiving signals over the serial link. The method includes issuing a shutdown command from the host data processing system to selected one of the devices over the link and responsive to the receipt of a power-off command at a device, causing the device to enter a low power standby mode on cessation of signal activity at one of the device ports. On entering standby mode at a device, standby power is supplied in the device to allow the device to monitor the one or more device ports for incoming signals. In addition, transmission of signals via the one or more ports is ceased. On receipt of a signal at any of the one or more ports that was previously inactive, power is restored to the device.

Growing community of inventors

Southampton, United Kingdom

Michael Alan Veal