Abstract: A method for reliably measuring preformatted servo patterns, on a magnetic tape, for positioning a magnetic head. The tape has constant frequency stripes marking servo pattern areas. The drive reading the preformatted tape has a read channel amplifier with automatic gain control (AGC). When a stripe is detected, AGC is enabled. Before leaving a stripe, AGC is placed on hold. The amplitudes of two servo bursts are then measured with a gain that has been calibrated by a signal from a stripe. During the time AGC is enabled, the amplifier peak output is limited to less than half the maximum amplifier peak output. The servo pattern signal amplitude is about twice the signal amplitude of a stripe, so that servo patterns are measured with almost the maximum signal-to-noise ratio. When a stripe is detected, a counter counts pulses resulting from the stripe signal, for a fixed time, to ensure that the stripe detection is valid.

Abstract: A method of calibrating signal processing circuitry in a magnetic data storage device. The method ensures that an adequate signal-to-noise ratio is achieved when reading a head-position calibration signal. First, discrimination thresholds are set to an initial low value. Then, with wide bandwidth and stationary media, amplifier gain is calibrated by adjusting gain to make the amplitude of amplified background noise equal to the initial threshold value. Finally, bandwidth is reduced and the discrimination thresholds are raised to a final value. The final threshold value ensures that a signal must exceed a predetermined signal-to-noise ratio before the signal is accepted as being valid.

Abstract: A method and apparatus for using a varying amplitude data signal from a data storage medium such as a magnetic disk or magnetic tape to calibrate the gain of the data signal amplifier to an optimal fixed gain. At initialization, amplified data signal peaks are detected over a data region of the data storage medium. The amplified signal peaks are compared to a predetermined reference. The signal amplifier gain is adjusted until only a few amplified signal peaks exceed the reference. The amplifier gain is then fixed at the final adjusted value.

Abstract: A tape drive control system with improved overall dam transfer rate. A streaming tape drive system for a multi-track serpentine data tape is controlled by a host computer. The data tape has a fixed number of data sectors per track. The host computer monitors tape position by observing data sector identification. The drive sends a ready/not-ready status signal to the host. The drive has a default mode. In the default mode, the drive generates an error signal if the host sends motor speed commands or head movement commands when the drive is sending a not-ready status. The host computer software can command the drive to enter a special mode. In the special mode, the drive does not generate an error if the host sends motor speed commands or head movement commands when the drive is sending a not-ready status.

Abstract: An apparatus and method for generating an index pulse by a data storage tape drive. The tape drive is controlled by a flexible disk controller. A multi-track tape is formatted into multiple data segments per track with erased areas between segments. A digital data signal from the tape signal processor is sampled to detect a lapse in data. Then, the analog data signal is continuously monitored to detect the reappearance of data. When filtered analog signal peaks exceed a fixed threshold, a pulse is generated from the tape drive to the flexible disk controller. In an alternative embodiment, to further protect against false triggering, index pulse generation is suppressed during most of each erased area between segments. In another embodiment, index pulse generation is suppressed if an erased area exceeds a length threshold, such as at the end of the tape. In still another embodiment, index pulse generation is suppressed if digital data reappears without triggering the analog monitoring circuit.

Abstract: A selectible computer tape drive activation and deactivation technique apparatus is disclosed. The invention integrates with existing floppy controllers in a manner which allows activation and deactivation of a computer tape drive without the need for select lines. The invention programs the floppy controller so as to generate an activation command which may be appended by an address to specify the specific drive involved. Both the command and the argument are chosen to be consistent with existing Quarter Inch Committee standards. With respect to the deselect method, additionally a failsafe, independent deactivation path exists to turn off the tape drive in the event any conflict in drive operations were to exist.