Abstract: A circuit for selective switching through of read signals of a multiple magnetic head in a magnetic layer memory, wherein each magnetic system of a multiple magnetic head is associated with a preamplifier which has spatially separated input and final stages, the input stage being located directly on the multiple magnetic head and connected to the final stage by means of a flexible connecting line, the final stage being spatially associated with a read channel, the final stage having switching means for the selective closing of a current path between the final stage and the associated input stage by means of a selection signal, the input stage being so constructed to be in an idle state for as long as the associated final stage is not activated. Preferably, outputs of all the final stages are connected in parallel and coupled into the read channel across an output stage constructed as a differential voltage amplifier.

Abstract: An electrostatic discharge noise suppression method and system is disclosed for electronic devices, particularly those connected to data buses. Electrostatic discharge protection is provided by breaking high-frequency ground loops by inserting common mode inductors where they can be most effective-in the DC power supplies themselves, in the DC power connections, or just behind the DC connector in the electronic devices. Saturation of the cores of the common mode inductors is prevented in a preferred way by equalizing supply and return currents in the common mode inductors and by preventing DC ground currents from flowing in a chassis between the power supply and the electronic device.

Abstract: In a belt-driven tape cartridge of the type used to store data on a magnetic tape in a high speed data storage and retrieval system, the tape must be maintained at a proper tension within the cartridge so as to maintain the tape taut against the write/read head. Slackness in the tape occurs after a repeated number of changes in the tape transport direction or start/stop events, because the tension experienced by the tape is not the same in both transport directions. In a belt-driven cartridge, the tape tension cannot be directly monitored. A method and apparatus for maintaining tape tension in a belt-driven cartridge are disclosed wherein tape tension is indirectly monitored by non-mechanically monitoring a selected tape characteristic, the characteristic changing as the tape tension changes.

Abstract: A method and apparatus for compensating the alternating electrical fields present at the front surface of a cathode ray picture tube wherein the high-voltage signal supplied to the high-voltage terminal of the tube is tapped to extract an alternating voltage signal therefrom, and the alternating voltage signal is inverted and amplified and then applied to a suitable external electrode placed in the proximity of the picture tube. The external electrode can be a framing band, an aquadag region or a ring electrode, among other things. Furthermore, combination of these electrodes can be employed.

Abstract: A drive unit for driving magnetic tape held within a tape cartridge, the tape cartridge engaged to the drive unit in abutting fashion. The drive unit provides an elastomeric drive belt which surrounds a drive pulley, a tensioning pulley and an engagement pulley, the engagement pulley resiliently urging the drive belt against a cartridge roller located within the cartridge which progresses the magnetic tape within the cartridge. The drive pulley is driven directly by motor which progresses the belt around the three rotating pulleys. The arrangement eliminates the need for a separate friction roller arranged above the drive belt by using the drive belt itself to drive the cartridge roller.

Abstract: A method and apparatus performs detection of an edge and detection of holes or other data patterns on a tape or other magnetic or optical medium. An array of photodetectors in an integrated circuit chip senses the intensity of light illuminating the chip with the tape running between a light source and the photodetectors. The holes or the other data patterns are sensed on the tape based on a comparison between detected light intensities with a programmable reference level. In addition, areas which may normally be sensed as a hole are discarded if these areas fall within a specified tolerance.

Abstract: A trackball system is provided wherein a roller ball is received and supported within a ball retaining assembly. A vertical height of the ball is adjusted relative to the housing by adjusting a vertical height of the ball assembly relative to the housing. By changing vertical height of the ball relative to a top surface of the housing having an aperture through which the ball protrudes, a selectable portion of the ball will protrude through the aperture. Thus, an operator may make height adjustments of the ball relative to the top housing surface to suit his individual preference.

Abstract: For the purpose of increasing storage density of data recorded on a magnetic recording medium, particularly on a magnetic tape, a coder stage is supplied with data signals allocated to the record data and with high-frequency magnetization signals. The coder stage generates write signals which are recorded with the magnetization signals. The pulse duration or the pulse pause of the respectively existing magnetization signal is lengthened given every change of the data signals. The magnetization signals and the data signals are preferably synchronized with one another such that the polarity of the magnetization of the recording medium changes at every change of the data signals. In the playback of the data, the peak values of the magnetization have zero axis crossings of the read output signals allocated to them. At the zero axis crossings, a detector stage generates data signals for a decoding of the recorded data.

Abstract: In a system for buffering data, a buffer memory is provided for buffering data output from a data source to an asynchronous data store. When a storage medium is provided in the data store and its storage capacity is exhausted, the data still contained in the buffer memory might not be recorded on the storage medium. Independently of the physical storage capacity of the buffer memory, the logical storage capacity thereof is dynamically adapted to the storage capacity of the data store which is still available. As long as the available storage capacity of the data store is greater than a maximum physical storage capacity of the buffer memory, the buffer memory remains unmodified. When, however, the storage capacity still available in the data store becomes less than the maximum storage capacity of the buffer memory, its logical storage capacity is reduced so that all data intermediately stored in the buffer memory can still always be stored on the storage medium.

Abstract: For precise positioning of a magnetic head to various tracks of a magnetic tape, deviations occur as a consequence of manufacturing tolerances of the magnetic head, or as a consequence of the adjustment thereof. Correction values are identified wherein a read head identifies a center of a track recorded by a write head. A moving direction of the magnetic tape is reversed and the center of the track is identified again. The read head identifies the center of a track recorded by a neighboring write head. Positional values allocated to the center of the tracks are subtracted from the positional value of the write head.

Abstract: In an arrangement for recording data or a magnetic recording medium, the inputs of an amplifier whose outputs are connected to a magnetic head are preceded by filters which delay magnetic bias signals and data signals supplied to the amplifier and limit their steepness. Undesirably high voltages at the magnetic head as a consequence of excessively steep edges of a write current supplied to the magnetic head are thus avoided, and the reliability of the recording of the data on the magnetic recording medium is increased.

Abstract: For recording digital data on a magnetic recording medium, binary data signals and magnetic bias signals having a constant repetition rate are synchronized in terms of phase, are overlaid, and are subsequently supplied to a magnetic head. The phase-oriented synchronization thus occurs since the chronological spacings between two successive signal edges of the magnetic bias signals between two successive signal edges of the data signals given a plurality of magnetic bias signals are modified such that the directions of the signal edges of the data signals coincide with the directions of the corresponding signal edges of the magnetic bias signals. The sums of the components having a first binary value and a second binary value of the magnetic bias signals are identical. Preferably, the distances between two successive signal edges of each of two magnetic bias signals are respectively shortened by half between two edges of a data signal.

Abstract: In a retrieval of data stored on a magnetic medium, a phase locked loop is employed for clocking data signals allocated to the data. This phase locked loop generates clock signals synchronized with the data signals. The data signals are subject to various distortions and are subject to a shift of individual data signals dependent on the recorded data. To prevent the phase locked loop from processing these shifts as phase or frequency errors, a switch stage is provided which inhibits the control in the phase locked loop give the occurrence of such shifts. The switch stage contains a time-delay stage and a comparator. The control is inhibited when successive phase differences between the data signals and the clock signals appear in opposite directions.

Abstract: Timing signals are generated in a prescribed time duration after signal edges of data signals. Integrated data signals, rather than the data signals themselves, are sampled with these timing signals. First, data contained in the data signals is recovered from the sampling signals generated by the sampling. Noise signals are eliminated by integration of the data signals, and the data is recovered with greater protection against disturbance. The integration can occur with analog or digital components, and it is possible to provide the sampling of the data signals in addition to the sampling of the integrated data signals in order, when warranted, to recover the data from the data signals, or from the integrated data signals, dependent on the respective disturbances.

Abstract: For cleaning a magnetic head in a magnetic tape recorder, the cassette is provided with a cleaning device and is inserted in the magnetic tape recorder instead of a magnetic tape cassette. The cleaning device contains a cleaning element located at a carrier, the cleaning element pressing against the front side of the magnetic head instead of the magnetic tape and converting a rotary motion of a drive arrangement which normally drives the magnetic tape into a reciprocating motion and, under given conditions, simultaneously converting the rotary motion into a pivoting or rotational motion of the cleaning element relative to the magnetic head. The tape drive capstan of the magnetic tape recorder preferably serves a drive arrangement and the carrier is driven via an eccentric shaft which may be inclined relative to its rotational axis and via a worm gearing driven by the tape drive capstan.

Abstract: A cleaning cassette has, at one longitudinal side, a cleaning element for cleaning a magnetic head of a magnetic tape recorder, and has a cleaning element at the opposite longitudinal side for cleaning a tape drive roller of the magnetic tape recorder. Dependent on the direction in which the cleaning cassette is introduced into the magnetic tape recorder, the one cleaning element comes into contact with the magnetic head, or the further cleaning element comes into contact with the tape drive roller, for the purpose of cleaning. The magnetic head is cleaned by a reciprocating motion of the cleaning element via an eccentric arrangement effected by the tape drive roller. The cleaning of the tape drive roller upon introduction of the cleaning cassette in an opposite direction occurs due to the rotational motion of the tape drive roller given a stationary, further cleaning element.

Abstract: To improve recording of data on a magnetic recording medium such as a magnetic tape, amplitudes of write signals supplied to a magnetic head are modified, dependent on distances between edges of the write signals. The modification occurs such that, given a short spacing, a respective write signal has a greater value than given a large spacing. Amplitudes of the write signals are modified in three steps when the GCR method is employed as a writing method for recording the data, distances of the edges of the write signals being capable of assuming three different values.

Abstract: For converting analog signals into binary signals which are respectively allocated to zero axis crossings of the analog signals, the analog signals are first converted into rectangular signals whose binary values change at the zero axis crossings of the analog signals. The rectangular signals are supplied to a delay unit which delays the rectangular signals in steps by a respective time duration which is short in comparison to a shortest period duration of the rectangular signals. Dependent on the various, simultaneously appearing binary values of the delayed rectangular signals, a processing unit generates binary signals which are respectively allocated to a correct zero axis crossing of the analog signals. The processing unit can contain a read-only memory and/or a microprocessor, and can also be fashioned such that it automatically adapts to disturbances present in the analog signals in order to generate correct binary signals, despite these disturbances.

Abstract: For exact positioning of a magnetic head to various tracks of a magnetic tape by use of a stepping motor, a plurality of motor control steps required in order to position the magnetic head to the various tracks proceeding from a reference position are identified. For the compensation of manufacturing tolerances, individual positional values are identified for every magnetic tape recorder. These positional values indicate a precise position of the magnetic head on the center of the respective track. The positional values are stored in a read-only memory, or are formed by addition of stored standard values and correction values stored in a read-only memory.

Abstract: In a system for controlling the motion of a magnetic head in a magnetic tape recorder, in order to achieve an optimally uniform wear of the magnetic head at a side thereof facing the magnetic tape, the magnetic head is constantly moved back and forth during a movement of the magnetic tape during at least one of the modes fast forward and rewind. In magnetic tape recorders wherein the magnetic head is positionable to various tracks of the magnetic tape transversely relative to the moving direction of the magnetic tape, wear on the head can occur at least partially during fast fast forward and rewinding modes. By moving the head during fast forward or rewind, the magnetic head is less heavily worn and the edges of the magnetic tape are not damaged by undesirable depressions in the head.