Abstract: Circuitry is provided for testing fusible link arrays for short circuits around the fusible links. Each link is electrically isolated and compared with a reference fusible link to detect the presence or absence of a short circuit.

Abstract: Circuitry is provided for testing fusible link arrays for short circuits around the fusible links. The resistance of each corresponding link in each of the four quandrants in the array is compared with the resistance of an array of reference fusible links to detect the presence or absence of a short circuit.

Abstract: PASS transistors are used to reduce the layout complexity of logic circuits by using PASS transistors connected to pass a first and second input function to an output node in response to selected control signals, thereby to generate a selected output function on the output node. The PASS transistor comprises a transistor capable of passing an input function in response to a control signal applied to the transistor thereby to generate an output function related to the input function. In general, the input function comprises less than all of a set of input variables and the control function comprises one or more of the remainder of the set of input variables.

Abstract: Relative humidity within a machine enclosure is controlled by means of a desiccant and a circulatory breather flow through the enclosure walls. The desiccant absorbs moisture during power off periods to keep the relative humidity down. During power on periods the enclosure temperature rises, which drives off the absorbed moisture from the desiccant. Operation of the machine also creates a pressure differential between two breather orifices in the enclosure walls so that there is a circulatory exchange of air between the enclosure and atmosphere. If the desiccant has absorbed a significant amount of moisture during power off periods, the moisture concentration within the enclosure will exceed that outside and there will be a net expulsion of moisture to partially recharge the desiccant.

Abstract: A head positioning system with automatic gain control for use in disk information storage apparatus employs multiphase radial position error signals derived from position reference information on the disk to control the position of a transducing head by means of a head positioning actuator. A variable gain amplifier amplifies the signals from the transducing head prior to their application to a position error signal generating means. The gain of the amplifier is controlled in a gain control loop by a gain function. The gain function is derived by combining the differnet phase position error signals to provide, at any position of the head, a measurement of the rate of change of the position error signals per track of displacement. This system affords gain control which is substantially independent of head width and limits variations in offtrack gain between heads.

Abstract: A servo system for a magnetic disk file having a voice coil motor (VCM) actuator generates a position error signal (PES) from servo information recorded on one of the disks. An electrical model of the VCM is employed through which a measure of the VCM electrical current is passed to generate a simulated PES signal which is continuous even if the regular PES is sampled or intermittent.

Abstract: PASS transistors are used to reduce the layout complexity of logic circuits by using PASS transistors connected to pass a first and second input function to an output node in response to selected CONTROL signals, thereby to generate a selected output function on the output node. The PASS transistor comprises a transistor capable of passing an input function in response to a CONTROL signal applied to the transistor thereby to generate an output function related to the input function. In general, the input function comprises less than all of a set of input variables and the CONTROL function comprises one or more of the remainder of the set of input variables.

Abstract: A magnetic recording disk substrate is provided with a capacitive servo pattern by implanting dopant material in the substrate to modify the substrate conductivity in a desired servo pattern.

Abstract: A method of making a rotor, for a dynamo-electric machine, which has a number of arcuately formed rectangular loop coils arranged edgewise in a cylindrical configuration, employs injection moulding. Moulding material is injected between adjacent coils and penetrates between and around them to form an encapsulating framework. Entry of moulding material into the central apertures of the coils is prevented by inserts. By directing the moulding material inwardly, and spacing the coils slightly from the mould core, encapsulant also penetrates behind the coil faces to form a thin skin. By use of a shutter member, which may be an integral end cap, coil terminations can be led out of the mould cavity through apertures in the shutter to protect them from damage during the moulding process.

Abstract: A servo system which generates a position error signal (PES) provides for periodically calibrating the magnitude of the PES to increase or decrease its magnitude as required by modifying the gain of a variable gain amplifier in the servo loop.

Abstract: PASS transistors are used to reduce the layout complexity of logic circuits by using PASS transistors connected to pass a first and second input function to an output node in response to selected CONTROL signals, thereby to generate a selected output function on the output node. The PASS transistor comprises a transistor capable of passing an input function in response to a CONTROL signal applied to the transistor thereby to generate an output function related to the input function. In general, the input function comprises less than all of a set of input variables and the CONTROL function comprises one or more of the remainder of the set of input variables.

Abstract: A storage stable, pre-selected magnetic coercivity is imparted to a recording disk having a film of heat curable magnetic coating composition thereon by curing the composition in an anaerobic atmosphere at a high temperature, and then heating, typically in air, at a lower temperature for a period of time effective to raise the coercivity to the pre-selected higher value.

Abstract: In a magnetic recording disk file in which one or more magnetic sliders rest on the surfaces of the disks when the disks are not rotating, a short oscillatory micromotion is imparted to the slider or sliders prior to starting rotation of the disks, this micromotion serving to free the slider or sliders from any stiction forces tending to bind them to the disk surface.

Abstract: A hermetically encapsulated magnetic record member is produced by applying a liquid mixture containing one or more organometallic compounds, an organic solvent system and magnetic particles to a thermally stable substrate, preferably of silicon. The applied mixture is then heated to melt the glass in the organometallic compound so that upon cooling of the glass, the magnetic particles are encapsulated therein.

Abstract: A method for modifying the surface properties of a material which applies a deformational force which exceeds the elastic limit of the material at the surface so that a plastic deformation of the surface occurs without modifying the bulk properties of the material.

Abstract: A process for producing an extremely smooth or planarized layer of material employs a polymeric material which, when melted has a viscosity enabling it to flow into all crevices and voids on the treated surface. Subsequent heating cures the polymer to form a planarized layer.

Abstract: A magnetizable recording disk is divided into data and servo sectors. The servo sectors include position reference information comprising a circumferentially extending and radially repeated magnetization pattern. Each such pattern comprises at least three subsets of elements from each of which a different phase of radial position error signal, indicating displacement from a data track center line, can be derived. The subsets are radially offset from each other by less than the pitch of the data tracks and their individual elements each have a radial width greater than the pitch of a data track. By making the width of the individual element of the servo pattern greater than that of the data tracks and, necessarily, greater than the physical width of the electromagnetic transducing head for reading and writing information on the disk, the contribution of neighboring elements to the signal sensed by the head via its fringing field is reduced.

Abstract: A method for improving the durability, surface finish, and magnetic properties of a magnetic recording disk, the recording disk having a magnetic coating material with load bearing particles therein, by applying thereto a deformational force which exceeds the elastic limit of the coating material.

Abstract: A track-seeking and track-following servo encodement and detection system employs a servo pattern using a reference signal and control signals, the control signals having an orthogonal phase relationship to each other by cyclically revolving in phase by 90.degree., 180.degree., 270.degree., and repeating this pattern every four tracks.

Abstract: In a magnetic recording disk file employing a transducing slider which is closely spaced from the disk surface and has side rail members extending in the direction of disk motion and tapered portions at the leading edge, the disk may be cleaned of contaminant particles by moving the slider in increments from the outside disk diameter to the inside diameter, so that the particles first encounter the slider/inner side rail and are swept away, rather than first encountering the tapered portions and being wedged into the magnetic coating.