Abstract: A frame buffer memory has a random access memory (RAM) for storing pixel data words, each word containing pixel data corresponding to a separate set of a plurality pixels along a horizontal raster line of a screen display. Each word is separately addressed.The RAM is organized into tiles, with each tile comprising an array of pixel data word rows and columns corresponding to a separate rectangular subset of horizontally and vertically contiguous display pixels. The RAM is addressed by sequentially applying row and column addresses. A first subset of the column address determines which pixel word row within each tile is addressed, while and a second subset of the column address determines which pixel word column within each tile is addressed. All other bits of the row and column addresses determine which tile is addressed.

Abstract: A waveform digitizer includes a sampling bridge for producing a sequence of analog samples of an input waveform, the samples being calibrated by an amplifier having adjustable offset and gain and then converted to digital quantities for storage in an addressable memory. The digitizer also includes memory and time base control circuits permitting real and equivalent time sampling of repetitive waveforms and logic circuits providing hardware averaging of multiple data samples.

Abstract: Touch controlled zoom of a waveform display uses a touch screen for the display surface. Function buttons for moving or expanding the waveform display and for determining the axis of such movement or expansion operate in conjunction with a rotary encoder. Expansion, or zoom, is accomplished by contacting the screen overlying a point on the waveform about which zoom is desired. Such contact or activation of the expand function button results in movement of the rotary encoder providing a gain parameter to a zoom function. The zoom function operates on the waveform display in an exponential manner as a function of the gain parameter to expand or contract the waveform display about the zoom point according to the direction of rotation of the rotary encoder.

Abstract: A dual channel time domain reflectometer includes a pair of input lines connected at respective nodes to a reference flat current pulse generator and a traveling wave sampling gate, respectively. The sampling gates are actuated by a balanced strobe generator which includes a waveguide coupler for coupling a high amplitude fast rise time pulse to each of the gates simultaneously. Pulses of requisite amplitude and shape are generated by a circuit responsive to a strobe trigger input which drives a step recovery diode.

Abstract: A data compression circuit has a compression mode of operation where it determines and stores minimum and maximum values of successive sequences of applied data words and provides an output comprising a pair of data words representing the stored minimum and maximum for each sequence, offset by a selected amount. The circuit also has a transparent mode of operation where output data sequences match input data sequences.

Abstract: A dense, sintered ceramic material having a low dielectric constant and a low coefficient of thermal expansion is provided from a mixture of 10-50 wt. % alumina, 0-30 wt. % fused silica, and 50-60 wt. % of a frit comprised of CaO, MgO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, and SiO.sub.2. The mixture has a minimum sintering temperature in the range of 850.degree.-1000.degree. C., and can be formed by conventional manufacturing techniques. It is particularly useful for the fabrication of single or multilayer electronic circuit substrates.

Abstract: A differential to a single-ended converter circuit includes linearizing PN junctions that compensate for input signal voltage loss in the input stage. A variable voltage source and a resistor are provided for adjusting the voltage produced across these junctions by varying the current through these junctions. The converter circuit also includes a shunt feedback amplifier for inverting half the differential output voltage so that it sums with the differential voltage of opposite phase to produce the single-ended output signal. The shunt feedback amplifier is operated at a constant current to minimize error voltages. Bootstrapping is employed to linearize thermal distortion of the PN junctions and means are provided for compensating for the resulting thermal distortion.

Abstract: A method of focusing and calibrating a display screen which is coupled to a video camera where the display screen is not visible when performing the calibration. The method includes the steps of generating a reference signal to display an image on the display screen, capturing an image of the display signal in the video camera and converting the image into digital signals representing the brightness of pixels in a pixel matrix, analyzing the digital signals for data representing predetermined physical parameters of the visual display on the screen, and generating on a separate display screen a graphic representation of these physical parameters. By observing the bar graphs on a microcomputer at the same time that adjustments are made to the focus, intensity, and rotation controls on the oscilloscope, the display screen may be focused and calibrated.

Abstract: An instrument for providing a principal display representing the variation of a first quantity as a function of a second quantity, comprises a display screen. A visually distinct dot is generated on the display screen and is deflected along one of two orthogonal axes in dependence upon the value of the first quantity and along the other axis in dependence upon the value of the second quantity. The dot is additionally deflected to selected positions along the two axes to generate an auxiliary display of a marker and of an information-conveying character adjacent the marker. The position of the auxiliary display is adjustable along at least one of the axes.

Abstract: A synchronous changeover device detects both peak amplitude and pulse width, automatically switching between sets of signals without a noticeable glitch when a fault is detected. The signals of each set are peak detected and combined so that if any signal of a set falls below a predetermined value a FAIL signal is output to a switch timing and control circuit. The FAIL signal, together with the sync signals from the sets of signals, causes an electronic switch to switch from one set of inputs to another between sync pulses, resulting in a synchronous changeover. Further the signals are input to a start/stop counter via a multiplexer under control of a microprocessor. The counter counts the number of pulses of a reference signal between the start and stop of a selected signal pulse, and the microprocessor determines if the pulse width is within acceptable limits. Out of limits pulse widths cause the microprocessor also to generate the FAIL signal to automatically switch between sets of signals.

Abstract: A transaction analyzer, for use in conjunction with a data acquisition system having a probe for accessing binary data, i.e. address and control signals appearing at the terminals of an operating microprocessor, determines the type of processor transaction occurring based on sequences of state changes occurring on a selected set of the control signals so accessed. The transaction analyzer then generates a binary number representing the transaction type which may be acquired by the acquisition system in conjunction with the data accessed by the probe. The transaction analyzer, which uses an asychronous state machine, also generates control signals used by the acquisition system to clock data storage along with a signal to control the direction of flow of data signals between the processor and the acquisition system.

Abstract: An electrostatic decelerating and scan expansion lens system (10) includes a mesh element (56) and operates in a cathode-ray tube (12) that incorporates a microchannel plate (24). The lens system is positioned downstream of the deflection structure (42 and 44) and provides linear magnification of the electron beam deflection angle. The mesh element is formed in the shape of a convex surface as viewed in the direction of travel of the electron beam (40) to provide a field with equipotential surfaces (100) of decreasing potential in the direction of electron beam travel. Secondary emission electrons generated by the mesh element as it intercepts the electron beam, are therefore, directed back toward the lens system and not toward the microchannel plate. Only the beam electrons strike the microchannel plate, which provides on the phosphorescent display (20) an image of high brightness, free from spurious light patterns.

Abstract: A remote master-slave control method uses a single command line from a master instrument to a slave instrument. Commands executed at the master instrument are transmitted to the slave instrument via the single command line, and are in turn executed by the slave instrument only if an operator controlled input is "on" at the time of receipt of the command. For instrument setups a recall command from the master instrument will be executed by the slave instrument if the operator controlled input was "on" at the time the instrument setup was stored.

Abstract: A digital phase-locked loop maintains a clock signal in a predetermined phase and frequency relationship with an input video signal having a repeating signal element, such as horizontal sync pulses and/or color burst signals. The clock signal is generated by a voltage controlled oscillator, the frequency of which depends on an input digital control signal. The input video signal is sampled by an analog-to-digital converter at the clock signal frequency to generate a succession of digital words representing the amplitudes of successive samples. A portion of the successive digital words is stored in a memory, the access to which is controlled so that the samples representing the repeating signal element are stored and then read out for processing by a microprocessor.

Abstract: A cursor interface for a waveform display provides for movement of a waveform relative to a first cursor. When the first cursor overlies a desired point on the waveform, the cursor is locked to the waveform by transforming the cursor coordinates from display coordinates to waveform coordinates. The waveform may then be moved together with the first cursor relative to a second cursor. When the second cursor overlies another desired point on the waveform, a measurement value is displayed indicating the difference in positions on the waveform of the cursors. The cursors may be centered independently, and when locked to the waveform the result is to correspondingly move the waveform.

Abstract: A tracking sample and hold phase detector operating as an error sampled feedback loop which takes signal samples during successive periods of an input signal with a sampling gate, holds the signal sample in a storage gate, and feeds back the sample to the sampling gate to allow the bias of the sampling gate to track the input signal level, thereby maintaining balance of the tracking circuit. A fast comparator detects the zero crossing level of the downconverted signal which is comprised of successive signal sample steps and has the shape of the input signal. The sampling gate comprises a diode bridge enabled by a balanced strobe, the input signal and the strobe being close or equal in frequency, the frequency of the downconverted signal being the difference frequency.

Abstract: A probe mount carries a probe with test points having ends in a test point plane. The probe mount is supported at three spaced apart locations by respective first, second and third supports, each adjacent to a respective one of the test points. These probe supports permit independent shifting of each of the three locations along respective parallel lines. As these locations are shifted relative to one another, the test point plane is tilted until it is parallel to a second plane containing the surface of an integrated circuit wafer to be probed. A test surface is positioned in the second plane and advanced toward the probe. As the test points contact the test surface, the test point plane is tilted. Microprocessor controlled stepper motors may be used to tilt the test point plane and to shift the test surface.

Abstract: A method and apparatus for automatically calibrating the deflection of an electron beam in a graticuled cathode ray tube. The apparatus includes a microprocessor and digital-to-analog converter for generating input signals of a predetermined accuracy and sending the signals to an amplifier of a cathode ray tube to deflect the electron beam across graticule lines on the faceplate. A phototransistor optically coupled to the faceplate detects the electron beam coinciding with the graticule and in response generates an electrical signal. Signal processing circuitry processes the signal to remove noise from it and retrieve detection signals. The microprocessor receives the detection signals from the signal processing circuitry, compares each detection signal to its corresponding input signal, and adjusts the gain and offset of the amplifier in response to the comparison. Additional circuitry digitally records the beam position relative to the graticule lines.

Abstract: A wafer probe head has a plate-form support member having a tip region and a mounting region. At least one electrically conductive probe tip is carried by the support member at the tip region. A connector is carried by the support member at a location spaced from the tip region, and the probe tip is electrically connected to the connector. The probe head also has a strain gauge for measuring physical distortion of the support member as a result of the probe tip being pressed against a device under test by virtue of relative movement between the mounting region of the support member and the device under test.

Abstract: A signal processing circuit for enabling a computer to quickly scan a memory having stored signals which represent a video image includes a flag generator responsive to a lit pixel detector for providing a flag signal to the memory to be stored in an address location indicating the presence of at least one lit pixel in that row. Incoming video, which includes data and sync signals, is digitized and examined by the lit pixel detector and a flag signal is clocked into memory at a predetermined address. The computer scans these address locations, which lie in a single column, to determine the identity of rows having a flag signal. This eliminates the need for the computer to scan the entire address space to locate an object of interest.