Abstract: A battery charging circuit includes a switching transistor which controls the flow of charging current to the battery at a high rate or a low rate. The operation of the transistor is, in turn, controlled by a voltage sensing circuit which includes a voltage detector module characterized in a very low current drain. The battery is, in fact, isolated from the charging circuit by a diode; the sensing circuit, however, is not isolated from the battery by a diode. This arrangement permits a more sensitive voltage detection and a more accurate control over the switching transistor. A desirable switching hysteresis is built into the sensing circuit but is operable to allow the hysteresis loop to be eliminated for purposes of calibration.

Abstract: In an energization circuit for a memory module, the primary energization is derived from a primary power supply source fed through an isolating diode to a regulating circuit. The regulating circuit includes a series regulator device such as a darlington amplifier. A voltage detector module is provided which is characterized in very accurate operation while drawing a negligible amount of current for its own operation. The output of the voltage detector is used to control the operation of the series regulator. A stand-by, or back-up, power supply, which may be a battery is connected to the regulator circuit through a further isolating diode.

Abstract: A display apparatus is provided whereby a constant intensity of record is obtained notwithstanding substantial changes in the linear speed of the record member. The cathode ray sweep frequency is maintained at a constant rate commensurate with the highest speed of the record member. As the speed of the record member is reduced by a given factor, the number of scans of the cathode ray beam which are unblanked are reduced by the same factor.

Abstract: A line scan cathode ray tube (CRT) recorder generates a hard copy record of a curve from stored data representing the X-Y coordinates of a series of sample points along the curve. The curve may be described mathematically by a multi-valued function. One pass of the recording media past a linear sweeping CRT beam records the entire curve in a predetermined number of recording sweeps. The distance (.DELTA.X and .DELTA.Y, respectively) between each and every X.sub.n, Y.sub.n and the next successive stored sample point X.sub.n+1, Y.sub.n+1 is determined prior to each recording sweep of the beam and these distances, .DELTA.X and .DELTA.Y, are divided by a predetermined number to give a factor interpolating the distance between successively stored data points (X.sub.n and X.sub.n+1 and Y.sub.n and Y.sub.n+1).

Abstract: A vector CRT display apparatus for faithfully reproducing an analog signal having high frequency components include an A-D converter, a digital minimum/maximum circuit and a recirculating shift register to derive from the signal, in successive sampling periods, two digital words representing, respectively, a minimum amplitude value date point and a maximum amplitude value data point of the signal. In each sampling period, the minimum/maximum circuit stores in the memory the most relevant of the minimum and maximum amplitude values and determine whether the remaining values should be held over to the next sampling period before it is stored, or can be discarded. As a result, if new minimum and new maximum amplitude values occur in the same sample period, one will be loaded into the memory and the other will be held over and loaded into the memory in the next sample period.

Abstract: A display apparatus includes a computational circuit that is connected to the output of a memory to introduce between a stored digital representation of successive sampled data points, by an interpolation method, additional virtual or interpolated data points. The interpolated data points are computed in accordance with the magnitudes of the separations or differences in value between the sampled data points. In a CRT display or hard copy recorder, this allows a higher cathode ray sweep speed, and hence, a higher density of raster lines, and consequently, an improvement in resolution, smoothness and continuity of the display, for a given size memory.

Abstract: An improved X-Y or vector type cathode ray tube circuit includes means to sense the imminence of and to inhibit excessive concentrations of electron beam current during the plotting of X-Y loops, which concentrations produce spots or points on the cathode ray tube screen that are essentially repetitive and convey no useful information to the observer, and if allowed to persist, tend to burn the phosphor coating of said screen.