Abstract: The present invention provides a complete digital data storage (DDS) magnetic tape system for utilization with a host unit. The invention comprises a host device interface for interfacing the host unit with the DDS system, a controller/formatter for encoding and decoding data from and to the magnetic tape, an automatic track follower (ATF) for performing automatic track following on the magnetic tape, a driver for driving the magnetic tape, a read/write (R/W) channel for channeling data thereto and therefrom, a read/write (R/W) head drum for transferring data to and from the magnetic tape, and the controller/formatter, the ATF, the driver, the R/W channel, and the R/W head drum all being under software programmable control.

Abstract: An automatic track follower (ATF) system for accurately positioning the read/write head on the tracks of a magnetic tape comprises a pilot signal generator for generating pilot signals from tape pilot marks; a sample-and-hold circuit for sampling the pilot signals from the tracks immediately adjacent a track being read; a comparator for comparing the magnitudes of the pilot signals from adjacent tracks on both sides of the track being read; a correction circuit for centering the read/write head on the track being read; and a processor for digitally controlling the generator, sample-and-hold circuit, comparator, and correction circuit and their functions, the digital control being under programmable control. Three code bit fields are discriminated from the digital data to detect the beginning of the ATF field on the tape to derive the ATF logic, timing, and control functions.

Abstract: In a digital data storage audio tape system having a host device interface unit, a main data buffer manager, a main data buffer, a processor, a data separator, a tape drive unit, and a read/write channel, this invention comprises a formatter providing track construction, encoding and decoding, error correction, and direct memory access of digital data transmitted between the host device unit and the tape drive unit and a frame buffer for buffering digital data for encoding and decoding, and error correction. The formatter is coupled between the main data buffer manager, via a direct memory access channel, and the read/write channel of the tape drive, and further is coupled to the frame buffer. The formatter is coupled to and responsive to instruction control by the processor in conjunction with instruction control of the tape drive unit by the processor.

Abstract: This invention is a beginning-of-tape/end-of-tape detection apparatus and method for use in a tape drive system having supply reel, take-up reel, and capstan motion sensors. The invention comprises monitoring means for monitoring each of the angular position signals and processor means for computing beginning-of-tape and end-of-tape utilizing the varying diameters of the supply reel and its tape pack and the take-up reel and its tape pack, and angular velocities of the reels and capstan. This invention provides a plurality of systems and methods for BOT/EOT detection with selectable tolerance levels. These include coarser detection without capstan engagement of tape (for use in high-speed spacing operations), finer detection utilizing capstan engagement, and absolute BOT/EOT detection utilizing the physical ends of the tape. This invention has the advantage of accurately determining beginning and end of tape without requiring special detectors.

Abstract: A complete digital data storage magnetic tape system for utilization with a host unit comprising a host device, an interface for interfacing the host unit with the DDS system, a controller for encoding and decoding data to and from the magnetic tape, an automatic track follower for performing automatic track following on the magnetic tape, a driver for driving the magnetic tape, a read/write channel for channeling data thereto and therefrom, a read/write head drum for transferring data to and from the magnetic tape, the controller, the automatic track follower, the driver, the read/write channel, and the read/write head drum all being under software programmable control.

Abstract: This invention is an improved digital data storage magnetic tape transport servo-control system comprising a tape supply reel and supply reel motor, a tension transducer, a head drum having at least one read/write head secured thereto and coupled to a head drum motor, a capstan and a capstan motor, a pinch roller, a take-up reel and a take-up reel motor. A processor provides programmable digital control signals to and responsive to signals from the supply reel, the supply reel motor, the tension transducer, the head drum, the head drum motor, the capstan, the capstan motor, the take-up reel, and the take-up reel motor. The processor controls tape tension in cooperation with the supply reel motor and the tension transducer, controls tape speed in cooperation with the capstan and the capstan motor, controls take-up reel torque in cooperation with the take-up reel and the take-up reel motor, and controls head drum speed in cooperation with the head drum and the head drum motor.

Abstract: This invention is a method and apparatus for the automatic calibration of the magnetic head offset angles in a helical scan rotating head drum and the generation of idealized track timing for recording and reading magnetic tape. A calibration tape is used to provide calibration marks and in conjunction with pulse generator (PG) encoder and frequency generator (FG) encoder signals, a processor calculates the offset angles. The offset is calculated from the time an FG signal edge occurs until the time of detection of a calibration feature. For a read head calibration, this provides a rough calibration of the angular location of the read head on the head drum. Using this rough calibration, data is read from the calibration tape, including the measured longitudinal position of the calibration feature. An accurate calibration of the angular location of the read head is then calculated.

Abstract: An apparatus and method for the commutation of a brushless dc motor having a rotor and a plurality of coils, and an encoder generating quadrature signals responsive to the rotation of the rotor. The commutation apparatus comprises a commutation control device, coupled to the encoder, for controlling the sequence of motor coil energization utilizing the quadrature signals. The commutation method utilizes the quadrature signals for composite signal generation, rotor rotational direction and position to achieve precise commutation. Precision commutation is achieved without the need for any additional commutation sensing devices.

Abstract: A mechanism for registering the tape contained within a cassette around a helical-scan head drum mechanism includes a sensor for sensing the presence of the tape cassette in a proper position for beginning the process of engagement of the tape in the cassette with the head assembly in the device. A symmetrical engagement mechanism includes two tape extraction roller blocks which sit at a first disengaged position. A tape extraction roller member for engaging the tape is mounted on each tape extraction roller block. When the presence of the cassette is sensed, the tape extraction roller blocks move along a predetermined path to a second, engaged position wherein the tape is correctly positioned around the head assembly. At a predetermined position along the path, a pair of symmetrically positioned entry-and-exit positioning rollers engage the tape and move it into position for passing it by the tape heads.

Abstract: A mechanism for registering the tape contained within a cassette around a hellical-scan head drum mechanism includes means for sensing the presence of the tape cassette in a proper position for beginning the process of engagement of the tape in the cassette with the head assembly in the device. A symmetrical engagement mechanism includes two tape extraction roller blocks which sit at a first disengaged position. A tape extraction roller member for engaging the tape is mounted on each tape extraction roller block. When the presence of the casssette is sensed, the tape extraction roller blocks move along a predetermined path to a second, engaged position wherein the tape is correctly positioned around the head assembly. At a predetermined position along the path, a pair of symmetrically positioned entry-and-exit positioning rollers engage the tape and move it into position for passing it by the tape heads.