Abstract: A computer system includes a first power rail having a first voltage level, such as 5 volts, and a second power rail having a second voltage level, such as 3.3 volts. A PCI connector receives a first type PCI card having I/O buffers operable at the first voltage level or receives a second type PCI card having adaptable I/O buffers operable at the first voltage level or the second voltage level. The PCI connector includes voltage I/O pins for supplying power to the I/O buffers. Sensing circuitry provides a sense signal having a first state when the first type PCI card is inserted and having a second state when the second type PCI card is inserted. Switching circuitry is responsive to the sense signal at the first state to provide the first voltage level on the voltage I/O pins and is responsive to the sense signal at the second state to provide the second voltage level on the voltage I/O pins.

Abstract: Method and apparatus for controlling a computer bus having first and second bus slots and operable with a bus controller at first and second data transfer rates. When the computer bus is operating at the first data transfer rate, the bus is partitioned so that the address/data pins of the bus controller are coupled to the address/data pins of both of the first and second bus slots, and the control pins of the bus controller are coupled only to the control pins of the second bus slot. When the computer bus is operating at the second data transfer rate, the bus is partitioned so that the address/data pins of the bus controller are coupled only to the address/data pins of the first bus slot, and the control pins of the bus controller are coupled only to the control pins of the first bus slot. The second data transfer rate may be faster than the first data transfer rate.

Abstract: The degree of variation in the normalized site attenuation of an RF test chamber may be reduced by adjusting the properties of the RF absorbers lining the walls of the RF test chamber such that for the frequencies of greatest variation the ground screen formed by the conductive floor of the chamber appears to be much greater than its actual finite size. This may be done by progressively reducing the degree of chamber wall absorption (for the frequencies of interest) for locations on the walls closer to the floor. The reduction begins at a height above the floor equal to the height of the device under test above the floor, and proceeds to some maximum reduction in absorption at the level of the floor. The reduction in absorption has the effect of making the ground screen appear to be much larger than it really is, and may be obtained either by spacing the absorbing tiles apart by increasing amounts nearer to the floor, or by using less absorptive tiles closer to the floor, or both.

Abstract: Unwanted RF emissions from an imperfect enclosure surrounding an electronic apparatus are reduced by first investigating the RF field strengths inside the enclosure while the apparatus is in operation, and identifying locations where the field strengths are significantly higher than elsewhere. The field strengths at these identified locations are then lowered significantly by placing lossy materials thereat to absorb and thus dissipate RF energy. If the lossy materials are placed in the near field of the actual circuitry that generates the RF then some of that RF is dissipated according to the degree of loading, but without associated reflected energy, and without the need for the lossy material to be a free field absorber that matches the characteristic impedance of the interior of the enclosure. A hybrid arrangement also exists where the lossy material is neither a free field absorber nor located in the near field of the generator, so long as it is located in the near field of a reflector.

Abstract: An enclosure for integrated circuit devices is disclosed. The enclosure includes a first portion which substantially encloses a plurality of secondary, relatively low-power integrated circuit devices and which includes a mechanism for contacting the secondary integrated circuit devices in order to conduct heat away. The enclosure also includes a second portion, which may include an active cooling device, directly in contact with a primary, relatively high-power primary integrated circuit device. In addition to removing heat, the first and second enclosure portions together shield the integrated circuit devices to contain electromagnetic energy generated by the devices. The first and second enclosure portions also allow different levels of force to be applied to the primary and secondary devices.

Abstract: A printed circuit board is shown to include at least one layer formed from electrically insulating material and a power plane formed on the layer. The outer perimeter of the power plane is spaced away from the outer edge of the layer thereby defining an outer area. A conductive structure is formed in the outer area, spaced from and surrounding the power plane and adapted to be connected to ground. Electromagnetic radiation emanating from the power plane is caused to terminate on the conductive structure. A multi-layered printed circuit board can also include a first layer of electrically insulating material, a ground plane formed on the first layer, a second layer of electrically insulating material and a power plane formed on the second layer. The outer perimeter of the power plane is spaced away from the outer edge of the second layer.

Abstract: An extensible bus assembly provides very short, uniform stub lengths from a bus transceiver to the bus assembly. The extensible bus assembly includes a bus termination cap, a plurality of extenders and an anchor. Each bus assembly element is L-shaped so that the bus transceiver, or some similar bus driver, may be positioned in close proximity to the bus assembly by placing the bus transceiver in the "corner" of the L; this ensures short, uniform stub lengths. Conductive surfaces are vertically positioned within the termination cap and plurality of extenders. The conductive surfaces may be compliant pins and/or spring-loaded wire conductors.

Abstract: A system and method are disclosed for automatically configuring the interconnection of circuit boards in slots on the backplane of a computer. Some signal lines, such as bus grant and interrupt acknowledge signals, must be daisy-chained, or connected in series through the circuit boards collectively. However, if a circuit board is not present, then the daisy-chain is broken. For each slot to be monitored in the backplane, the present invention envisions implementing a generator, a valid logic level detector and a signal selector. The generator imposes an invalid logic signal onto an output connector of a slot to derive an input for the valid logic level detector. Based upon the input, the detector determines whether a circuit board resides in the slot. Accordingly, the detector adjusts the signal selector to either bypass the slot or connect the slot, as well as the present circuit board, to the daisy-chain.

Abstract: A printed circuit board for mounting in a housing, having a mounted connector for making connections with the circuit board through the housing includes a layer formed from electrically insulating material and a conductive structure formed on such layer which conductive structure is adapted to be connected to ground. A casing, also formed from electrically conductive material, is shaped to surround a portion of the connector and is electrically connected to the conductive structure so that electromagnetic radiation emanating from the circuit board will not pass through the connector. In embodiments where the connector is mounted on an edge of said circuit board, the casing surrounds all of but the open end of the connector. In a preferred embodiment the casing includes a top portion, connected to the conductive structure, for surrounding the top of the connector and a bottom portion, also connected to the conductive structure, for surrounding the bottom portion of the connector.