Abstract: An enclosure for data processing apparatus has a tambour door that slides in a track to partially open the front of the processor enclosure. The tambour door retracts completely into a canister that has a U shaped track that carries the tambour door. The canister is hinged along one edge of the processor frame so that the canister can be swung out to permit access completely along the front of the enclosure with a minimum of interference from the door and canister and with a minimum intrusion into an aisle alongside the processor.

Abstract: In a video disk system a mark along a record data track is modulated in length to represent multi-bit binary code blocks of a first length (such as three or fout bits) and the player system associated with the disk operates in multi-bit code blocks that are generally longer (for example eight bits) so that two marks on the disk may represent a single code block in the associated system. The bits of the code block in the associated system are assigned to bit positions of the appropriate number of marks on the disk in a way that minimizes the effect of errors in the operation of initially writing or subsequently reading a mark. The increments of mark length are also made non-linear to further minimize the effect in the associated system of errors in mark length.

Abstract: An apparatus for performing a Hadamard transform on video data for compression of data to be recorded and decompression of data read from a record for display achieves the necessary high rate by means of two or more adders and two subtractors operating in parallel. A store that holds the data during successive passes through an arithmetic unit has accessing circuits and a set of registers and associated gates that fetch and store the data in a repetitive sequence that simplifies storage accessing. Data is processed in units that represent for example eight lines of a television picture and an output buffer is provided for the decompressor of a video disk player that receives data as it is processed and holds previously processed data unit by a storage accessing circuit that minimizes the amount of buffer storage that must be provided in the player.

Abstract: A digital signature machine provides a simplified method of forming and verifying a signature that is appended to a digital message. A sender transmits a signature with the usual signature keys and with validation table entries that correspond to the unsent keys and with the compressed encoding of the next validation table. The receiver uses the compressed encoding of the next validation table to form validation table entries from the signature keys so that the receiver has a full validation table. This validation table is compressed and compared with the compressed encoding which was received from the sender in a preceding message.

Abstract: A new plastic-metal composite material and method of preparing the material is disclosed. Fibers that are coated with metal form a matrix in the plastic that gives the composite material sufficient electrical and thermal conductivity for many applications. In a preferred embodiment of the new method of this invention, metal is formed on glass fibers by vacuum deposition and the metal coated fibers are combined with a selected plastic in a pellet form that is suitable for injection molding operations.

Abstract: A new capacitive tablet has a single layer in which electrodes provide capacitive coupling with a pen to produce signals that correspond to the X and Y dimensions of the position of the pen on the tablet. The electrodes in the single layer are in the form of pairs of complementary shaped, closely adjacent, conductive elements that extend in the Y dimension of the tablet. For sensing the pen position in the Y dimension, an alternating voltage is applied between the two elements of a pair and the pen receives a signal that is a function of the pen position in the Y dimension. The tablet includes a number of such pairs, each having a different X dimension position, and for sensing the pen position in the X dimension, the two electrodes of a pair are given an alternating voltage that differs progressively across the X dimension of the tablet.

Abstract: In a data processing system having a plurality of channels that are organized for separately processing the operations of specific I/O devices and the operations that are background to these specific operations, apparatus for transferring the background processing from one channel to another channel to distribute the background processing load. A system of registers and lines connect these registers to the channels for controlling these operations. Each channel processor has a request register for use in designating that background processing has been completed and that processing of a device oriented portion of a channel program is to begin, and a completion register set by an associated I/O processor for use in signifying that processing of a device oriented portion of a channel program has been completed and that background processing is to begin.

Abstract: During the construction of display gas panels front and back panels are connected together by means of a seal which forms a chamber for receiving a display gas. A hole is provided in the back plate which is outside the display viewing area and a glass tube is fitted into this hole and sealed to the assembly. The tube is used to first evacuate and then admit display gas into the chamber. An electric tip-off oven is used to collapse the tube stem to form a permanent seal. A cast protective heat sink and a reflective foil wafer are used to protect the gas panel and the tube-to-gas panel interface from damage by the oven.

Abstract: Apparatus for signalling the occurrence of a match between an address that is supplied to a control store and an address that is to be watched for in a data processing system that executes several instruction streams concurrently. The apparatus signals the occurrence of a storage accessing operation at a location that is uniquely identified only by a virtual address that is longer than the actual address used in accessing the store. Means is provided for comparing the actual address used in accessing the store with the corresponding portion of the complete address, and means is provided for recording the location of an address to be watched for in a particular frame of the store and for signalling a match that occurs in such a frame. The apparatus is useful for testing the operation of the data processing system by relating a recurring malfunction of the system to the execution of an instruction at the address that is watched for.

Abstract: A thermally conducting cushion-like elastomeric pad of RTV (Room Temperature Vulcanized) silicone rubber moled with indentations in one surface to fit in glove-like relationship with electronic components situated on a component carrying card, the opposite surface mounted flush with a heat sink such that the heat generated by the electronic components is transferred through the pad to the heat sink.

Abstract: A set of closely spaced, parallel conductive lines on an insulating support are located in face to face electrical contact with a corresponding set of conductive lines on a second insulating support, and a new structure is provided for adjusting the two sets of lines to match properly despite variations in the spacing between the lines of a set. The first set of lines has close, even, spacing. In the second set, the lines converge slightly from a spacing that is wider than the spacing of the first set to a spacing that is narrower than the spacing of the first set. During assembly, the position where contact occurs between the two sets is adjusted so that satisfactory electrical contact is made between each pair of lines.

Abstract: A circuit for supplying sustain voltage pulses to the orthogonal conductors of a gas display panel including voltage sensors to sense any change in sustain voltage amplitude with aging of the circuits and a voltage controlled oscillator to shift the operating frequency of sustain pulses as the amplitude changes. In that manner, the operating point of sustain voltage vs. frequency is shifted to take advantage of the slope in a graphical representation of sustain voltage margin to allow for shifting of the margin due to panel aging.

Abstract: An improved operation is provided for a graphic tablet of the type in which a pen is capacitively coupled to sets of X dimension wires and Y dimension wires that are digitally activated to produce a pen signal that signifies the position of the pen on the tablet. Compensation is provided for variations in the pen signal that are attributable only to differences in the height of the pen above the tablet as the pen is operated over intervening layers of paper of various thicknesses. The drivers that activate the tablet are controlled to establish a sequence of different activation patterns and a corresponding sequence of analog pen signals. These signals are operated on to produce a pen position address that is substantially compensated for variations in pen height.

Abstract: This invention relates to a system for communicating between a central station, such as a host processor, and one or more remote stations, such as terminal devices, on a pair of communication loops. A remote station operates normally on a selected one of the loops (the primary loop for the station) and it has access to but does not normally use the other loop (the secondary loop for the station). An improved apparatus and method is provided for switching a remote station from its primary loop to its secondary loop when its primary loop is disabled. Means is provided for a remote station to listen to messages on its secondary loop. For switching the remote stations from a disabled primary loop, a unique command is transmitted on their secondary loop. Remote devices operating with a primary connection to the loop that carries this command recognize the command and respond in a non-interferring way.

Abstract: An improved light pen is provided for a gas display panel of the type in which an alternating polarity sustain voltage produces a succession of brief light flashes in a matrix of light emitting cells. The timing for the sustain voltage is disturbed along a selected coordinate of the matrix. The coordinate of a light pen is identified when light with this disturbed timing is detected by the pen. Circuits for disturbing the sustain voltage of an individual cell of the matrix are also disclosed.

Abstract: A plasma display panel has twin X and twin Y orthogonal drive lines in place of the single X and single Y drive lines of prior art panels. Each pair of twin drive lines are in close proximity and spaced a relatively much greater distance from the next pair. The dielectric layer covering the drive lines is sufficiently thick to cause the voltage potentials on the twin drive lines to image as one potential on the surface of the dielectric. Each one of the twin drive lines is connected to a selection line such that the raising of any two X selection lines and two Y selection lines produces a write-erase potential on a particular gas cell.

Abstract: An improved write waveform is provided for a gas panel of the type in which light emitting cells are formed in an ionizable medium at the cross points of a set of horizontally and vertically extending insulated wires. A write pulse of high amplitude is followed by an opposite polarity pulse of an amplitude and width to produce cell wall charge storage from the ionization that accompanies the fall of the high amplitude write pulse. The invention also provides a method and circuit for reading the state of a cell by applying the high amplitude write pulse to a cell and detecting the difference between the smaller current that occurs at the leading edge of the write pulse for a previously written cell and the larger current for an erased cell.