Abstract: A large-capacity CAM (content addressable memory) is disclosed. RAM core cells are used to store the CAM data. The comparison function is not performed in the core cells, but rather in comparators which are placed adjacent to a plurality of core cells, in such a way that the plurality of core cells shares access to a single comparator. Access to the comparator is shared by a time-division multiplexed means, requiring a plurality of serialized operations. These operations are self-timed and transparent to the user, because they occur in a single cycle of the externally-supplied clock.

Abstract: A Mach-Zehnder optical modulator is provided having first and second modulation electrodes on respective first and second interferometric arms for receiving modulating electric fields, and the two modulation electrodes are of different lengths, the ratio of the lengths being designed to control the relative bias of the two arms, thereby provide for adjustment and optimization of frequency chirp, in a positive or negative chirp MZ modulator or in a configurable chirp MZ modulator. The modulator may have an asymmetric input y-junction coupler and an asymmetric output y-junction coupler to provide unequal power splitting, and interferometric arms defining two optical paths, which may be of equal or unequal length so as to generate a fixed phase difference of 0, .pi. or .pi./2. Preferably, the device is operated with equal push-pull drive, although non-equal push pull drive may alternatively be used.

Abstract: An electronics enclosure includes an assembly of wall elements having metallic surfaces with a standard oxidization potential within the range of -0.25 to +0.5 volts, the wall elements rigidly secured together, and having a coating of molybdenum phosphate covering the metallic surfaces of the wall elements and providing electrical discharge continuity around the enclosure. The molybdenum phosphate coating provides a required degree of electrical conductivity for adequate electrostatic discharge thereby providing a Faraday cage to filter out any electromagnetic radiation attempting to pass through the enclosure. Of particular importance in the structure is the feature that the molybdenum phosphate is particularly effective as an electromagnetic interference element at junctures between wall elements of the enclosure. The molybdenum phosphate coating may be applied to the wall elements either prior to assembly or following assembly.

Abstract: A thin film resistor for optoelectronic integrated circuits is described. A stable low resistance, thin film resistor comprising a bilayer of platinum on titanium is provided. Advantageously, the resistive layer is protected by a layer of dielectric, e.g. silicon dioxide or silicon nitride to reduce degradation from humidity an under high temperature operation at 300.degree. C. or more. The resistor may be formed on various substrates, including silicon dioxide, silicon nitride and semiconductor substrates. Applications for optoelectronic integrated circuits include integrated resistive heaters for wavelength fine tuning of a semiconductor laser array.

Abstract: An electronic unit with a mother board carrier beneath a service carrier in a housing. The carriers are independently movable between retracted use positions and forward access positions for maintenance. Service components are hence of no hindrance when removing printed circuit boards from the mother board carrier. The mother board is horizontal with the primary surface facing upwards. This latter feature together with the orientation of other printed circuit boards and of the service components minimizes the frontal area of the unit and provides pathways for front-to-rear cooling air flow. A connector arrangement connects the two carriers together only when both carriers are in their retracted use positions. Flexible lengths of cable extending between the carriers together with attendant stowage and hindrance problems are thus avoided. A retaining bar structure is included which acts at multiple positions against daughter boards to hold them securely against vibration during transporting and also in use.

Abstract: A content addressable memory employs a word-sliced architecture, in order to localize word match logic, and a global data bus, to convey data between the memory input/output circuitry and the plurality of word slices. Timing information is embedded in the global data bus in the form of a model global data signal. This signal interacts with two major control signals to self-time the memory. The number of major control signals is such that all possible memory states are uniquely represented, but the memory cannot power-up in an invalid or unrecoverable state. Three model timing paths are used to match the delay of the self-timing loop with that of the actual operation: one each for READ, WRITE and SEARCH.

Abstract: Binary and multiple-valued nonvolatile content addressable memories (NVCAMs) use ferroelectric capacitors as nonvolatile storage elements. The operation of the NVCAMs is accessed either in serial or in parallel. In a 2-bit NVCAM of a parallel access structure, search operation is performed by a simultaneous access to a 4-level polarization of the ferroelectric capacitor. The total number of search operations is reduced.

Abstract: An optical repeater is described which integrates an erbium doped optical fiber amplifier (EDFA) with a dispersion equalizer (DE) based on fiber gratings. The dispersion equalizer is based on parallel connection of two fiber gratings for single carrier wavelength operation, and on parallel connection of a cascade of two fibre grating branches, each carrying a plurality grating elements chirped for different wavelengths, for WDM operation at a plurality of wavelengths.The use of two gratings sections for each wavelength improves the optical bandwidth of the equalizer compared with single grating designs, doubling the effective bandwidth. Further, the grating DE is disposed between two fiber amplifier sections which share a single pump laser. Thus, this arrangement provides dispersion compensation and loss compensation in an optical repeater of lower cost, and smaller size, compared to a system of similar performance configured using discrete components.

Abstract: A multi-port RAM (random access memory) includes RAM cells which are coupled to respective row and column lines of each port. RAM cells selected by signals on the row and column lines of a port store binary data. A ground level voltage is applied onto selected column lines in a shadow write mode. Any short between the active column lines and the column lines in shadow write will result in a significant error voltage being applied to the active column line and invalid read will result. Shorts between column lines from different ports are sensitized.

Abstract: Disclosed is an architecture of a RAM (random access memory) with BIST (built-in self test) or functional test function. The RAM has a memory cell for storing differential or single-ended binary data and bit line signals are fully differential or single-ended. Shadow write is applied to read only and read-write bit lines. With the test function, port-to-port bit line shorts and port-to-port word line shorts are sensitized.

Abstract: A network unit enclosure adapted for exposure to humidity and airborne contaminants defines a sealed first chamber and an adjacent second chamber. The two chambers are sealingly separated by a circuitry substrate on which electronic components are mounted in the first chamber and through which conductor connection means in the second chamber are connected to electronic components in the first chamber. An outer wall bordering the second chamber includes a hole for providing an electrical cable feedthrough. The enclosure may also define a third chamber, and a wall separating the first and third chamber including a sealed feedthrough for an optical fiber segment connected at one end to an opto-electronic component in the first chamber and the other end for connection to an optical fiber from an optical cable passed through an access hole in an outer wall bordering the third chamber.

Abstract: A portable wireless telephone structure in which a foldable wallet carries a telephone in addition to having a pocket to house paper currency. The telephone is exposed for use with the wallet in open condition and is housed with the wallet in closed condition. The telephone has a communication mode to a user monetary function to permit telephonic transfer of monetary units. Thus, the telephone may eliminate need for carrying credit or bank cards in the wallet except for the telephone use with a "smart" card for telephonic transfer of monetary amounts to the "smart" card for transaction purposes.

Abstract: The invention relates to apparatus and method for efficiently removing humidity from a chamber. A thermoelectric cooler with a maintained temperature differential between the cool and warm sides of the cooler is used to condense the humidity from within the chamber upon the cool side of the cooler. The condensate is transferred to the warm side of the cooler and then removed through the capillary penetration into a porous structure of an evaporator at the warm side of the cooler and further evaporation. During evaporation, the condensate extracts heat from the warm side of the cooler, the temperature of the cool side of the cooler being also decreased, which results in an increase of the overall efficiency of the apparatus.

Abstract: Mounting for holding a planar electronic device, e.g. a printed circuit board in electronic slots to receive edges of the electronic device and a clamp is inserted into each slot to clamp an edge of the device in heat conductive engagement with a side surface of the slot. The clamp has a rigid elongate clamp element inserted along the slot, springs to urge the clamp element towards the side surface of the clamp to provide a clamping action and a lever to move the clamp element out of a clamping position to release the electronic device.

Abstract: A method of etching of indium phosphide (InP) semiconductor materials using methyl chloride CH.sub.3 Cl and phosphine PH.sub.3 in a low pressure MOCVD reactor is provided. Etching of InP using CH.sub.3 Cl as an etchant and PH.sub.3 to prevent thermal decomposition of the etched surface gives excellent etching morphology, and a maximum etching rate of 0.75 mm/hr for the CH.sub.3 Cl flow rates studied. A PH.sub.3 flow rate.ltoreq.40 SCCM and etching temperature.gtoreq.610.degree. C. provided excellent etch morphology, without formation of pits, independent of the CH.sub.3 Cl flow rate. A controllable etching rate was obtained for a coated susceptor when deposits are primarily InP. Thus this method of CH.sub.3 Cl etching is suitable for multiple growth and etching steps using an MOCVD reactor. By controlling the PH.sub.

Abstract: An environmental protection housing for an optical fiber connector having two housing parts to define an environmentally protected chamber to house the connector. The housing is for use for housing a connector upon suspended cable. So as to prevent the weight of the cable being taken by the connector when the housing parts are separated, a movement limiting device is provided an which extends between the housing members. This movement limiting device comprises an elongate rigid member which is capable of preventing relative rotation or change in relative orientation of the housing parts while the rigid member extends between the housing parts. With the connector uncoupled and thus the danger of the loading of the cable being taken upon the connector in coupled condition, the connector is releasable from one or both of the housing parts.

Abstract: The implementation of two-dimensional decoding, necessary to achieve a reasonable array aspect ratio for a large content addressable memory, is achieved by having multiple match lines per physical row, these match lines being physically routed on top of the array core cell in an upper metal layer. To limit power dissipation in the resulting large-capacity content addressable memory, the match function is implemented by two or more NAND chains per word. Means for achieving the precharging and evaluation of these chains, and for implementing dummy chains for the provision of timing information, are also disclosed.

Abstract: Electronic unit in which a heat conductive mounting comprises two spaced apart holding elements providing a receiving station for a printed circuit board. Edge regions of the board are in heat conductive engagement with the holding elements. Heat is conducted from electronic components on the board into the holding elements and from there into heat pipes connected to the holding elements. A housing around the heat pipes has apertures for flow of cooling air around the heat pipes. Part of the housing around the receiving station is thermally insulated thereby ensuring that substantially all of the heat is removed through the heat pipes.

Abstract: An analytical fault diagnostic methodology for use in complex VLSI chips. The method assumes a scan design environment and is capable of locating errors to the scan flops that capture the errors during test, independently of the number of errors that the circuit-under-test produces. The methodology is also capable of identifying the test vector or vectors under which the errors are generated. The apparatus which is designed to implement the method is also described. As the apparatus requires little hardware, the method is practical for chip level applications.

Abstract: A large-capacity CAM (content addressable memory) is disclosed. RAM core cells are used to store the CAM data. The comparison function is not performed in the core cells, but rather in comparators which are placed adjacent to a plurality of core cells, in such a way that the plurality of core cells shares access to a single comparator. Access to the comparator is shared by a time-division multiplexed means, requiring a plurality of serialized operations. These operations are self-timed and transparent to the user, because they occur in a single cycle of the externally-supplied clock.