Abstract: Magnetic recording apparatus employing a medium characterized by having a relatively high coercivity recording layer having servo tracks recorded therein, and a second layer of lower coercivity in which data may be recorded. The servo tracks are read by a head and this signal is used to properly position the head for writing and reading of data. If the medium is a disc, e.g. the servo tracks may be either concentric circles or a single spiral concentric with the center of the disc.

Abstract: A roller platen imprinter is provided with means for selectively raising and lowering the roller platen for the imprinting and return strokes. The said means includes regions on the platen shaft of different sectional dimensions, together with cam means for axially shifting the support position of the shaft between the portion having the large sectional dimension and the portion having the smaller sectional dimension to selectively raise and lower the platen.

Abstract: An article and a method for manufacturing the same, for use as a jaw face of a vise and which applies pressure evenly along any approximately flat surface clamped therein. The face comprises a plurality of cantilevered beams integral with the body of the jaw. The beams are spaced apart from each other and in the preferred embodiment have along a corresponding exterior surface of each, a pair of projections the tips of which are tangent to a geometrically flat plane. When the jaw is used, the projections bear against a flat surface of the workpiece to be clamped and the individual beams deflect slightly to correct for deviations from flatness in the flat surface, thereby assuring that the clamping force is distributed relatively evenly along the surface.

Abstract: A document turn-around sorter/stacker comprised of a transport pinch drive roller for driving a sheet up an upwardly sloped ramp until it is released, whereafter it slides back until it re-engages the original roller at a different location and is driven over a pivotable curved sort gate onto a preselected stack.

Abstract: In a magnetic disk file head positioning control system, the servo loop controlling the fine positioning of magnetic heads for a particular head track is responsive to a servo error signal. The servo error signal consists of a low pass filtered head position error signal summed with a pseudo velocity signal derived from the same head position error signal.

Abstract: Apparatus for changing a dimension of the light-producing area in a display element of the type which emits light from any portion of an interface zone across which a voltage exceeding a certain threshold is established, by varying this voltage. A bias voltage source provides a potential along one side of the interface zone, which increases from one end to the other, with respect to the other side. The apparatus is particularly well suited for an electronic bar graph type indicator. Gas discharge devices such as plasma tubes, and LED's are particularly suitable types of display elements.

Abstract: Apparatus for measuring a dimension of a specimen whose image is projected by an optical system into a television camera or other light scanner, by forming the ratio of the time required to scan across the unknown dimension, with the time required to scan across the image of a reference dimension. The reference dimension is the width of an object placed in a focal plane of the optical system other than the focal plane in which the specimen having unknown dimension to be measured is placed.In a preferred embodiment, the apparatus includes a variable frequency oscillator which performs the measurements for the times required to scan these two dimensions. A feedback loop adjusts oscillator frequency so that the number of oscillations during the scan of the reference object equals the number stored in a register which can be altered only manually. This preferred embodiment can be calibrated by placing an object of known dimension within the field of view reserved for the specimen.

Abstract: An automatic gain control circuit including a wide band digitally controlled amplifier particularly adapted for use with recurring signals. Each of the recurring signals is divided into a large number of discrete time intervals and the gain of the amplifier may be adjusted for each time interval independently of the signal in any other of the time intervals. Transients due to gain modification may be superimposed.

Abstract: Apparatus is provided for forming an absolute address for accessing the memory of a computer in which a plurality of associative registers each containing an associative word are arranged in sequential order, each associative word having an absolute page identifier and a virtual page identifier. Means is provided for comparing the virtual page identifier of the associative words with a virtual page identifier of a job program, and means is provided for sequentially shifting the associative words so that the associative word containing the virtual page identifier which corresponds to the virtual page identifier of the job program is placed in the highest ordered associative register.

Abstract: A shift network is provided which may operate on one full width operand or on two one-half width operands, by splitting the shift network in the middle. The shift network in the present embodiment for 96 bit full width operands is constructed in four ranks so that the first rank shifts operand bits 0, 1, 2 or 3 bit positions, the second rank shifts operand bits 0 or 4 bit positions, the third rank shifts operand bits 0, 32, 64 or 96 bit positions, and the fourth rank shifts operand bits 0, 8, 16 or 24 bit positions, all shifts dependent upon the input shift count.The shift network is responsive to two independent shift counts and a control signal specifying the half width mode when it is desired to split the network. Each rank of the shift network is divided into an upper half and a lower half. Special logic circuits are provided to extend the sign bit for the lower half operand into the lower half of each rank when operating in the two operand mode.