Abstract: An apparatus for encoding digital data for storage on a data storage medium includes a non-deterministic randomizer code generator. The randomizer code generator may select different randomizer codes for different portions of the data to be stored. The randomizer code used to randomize a given portion of the data may be stored on the media for use in subsequent data retrieval.

Abstract: A media element library includes a magazine of media element storage locations comprising at least one cell adjacent to an opening in the housing. The cell may be moveable so as to extend toward the opening in the housing of the media element library, thereby facilitating user access to a media element stored in the moveable cell.

Abstract: A media element library defines a viral configuration different from the physical configuration of media and drives actually present in the library. A plurality of host computer systems communicate with the library as if they were communicating with a conventional library having a physical configuration identical to the virtual configuration defined by the library.

Abstract: An apparatus for encoding digital data for storage on a data storage medium includes a non-deterministic randomizer code generator. The randomizer code generator may select different randomizer codes for different portions of the data to be stored. The randomizer code used to randomize a given portion of the data may be stored on the media for use in subsequent data retrieval.

Abstract: The present invention provides an apparatus and method of partitioning a recording medium data track into two longitudinal regions and erasing any preexisting signal on each region with a DC bias signal of polarity opposite to that of the other region. Magnetic transitions subsequently recorded over the two track regions will be shifted differently depending on the relationship of the polarity of the signal being encoded to that of the DC bias erase signal applied to each region. The complementary lead/lag errors from the two track regions produce a combined read head waveform in which the timing errors are substantially eliminated, thereby reducing system bit error rates and allowing increased data density on the medium. An apparatus and method of controlling the lateral position of the various heads are also disclosed.

Abstract: A digital data recording channel which uses variable rate encoding. The encoder monitors an input bit stream for sequences associated with selected readback characteristics, and inserts one or more bits where desirable to improve the characteristics of the stored bit stream.

Abstract: An apparatus for encoding digital data for storage on a data storage medium includes a non-deterministic randomizer code generator. The randomizer code generator may select different randomizer codes for different portions of the data to be stored. The randomizer code used to randomize a given portion of the data may be stored on the media for use in subsequent data retrieval.

Abstract: The present invention provides an apparatus and method of partitioning a recording medium data track into two longitudinal regions and erasing any preexisting signal on each region with a DC bias signal of polarity opposite to that of the other region. Magnetic transitions subsequently recorded over the two track regions will be shifted differently depending on the relationship of the polarity of the signal being encoded to that of the DC bias erase signal applied to each region. The complementary lead/lag errors from the two track regions produce a combined read head waveform in which the timing errors are substantially eliminated, thereby reducing system bit error rates and allowing increased data density on the medium. An apparatus and method of controlling the lateral position of the various heads are also disclosed.

Abstract: A data storage and retrieval system minimizes mechanical complexity and maximizes system flexibility by providing a modular rack mountable system which includes a passive transfer carriage for transferring media elements within the system. An active transfer carriage including a picker which is adapted to engage a notch on the media elements is also provided. The active transfer carriage may transfer media elements to the passive transfer carriage, and may also retrieve them from the passive transfer carriage. Drive actuation is automated with an extendable plunger which is adapted to engage an end of an actuation arm coupled to a media element reader such as a tape drive.

Abstract: A magnetic tape cartridge library includes a memory which stores calibration parameters associated with the tape cartridges and the tape drives. The tape cartridges preferably have a cartridge identifier written to the tape in a plurality of locations along the tape. When a tape cartridge is inserted into a tape drive, the appropriate calibration parameters are retrieved in order to bypass a tape drive initialization sequence.

Abstract: A variable rate bit inserter is provided which efficiently encodes data prior to writing to a magnetic storage media. In a preferred embodiment, the bit insertion technique monitors the phase and amplitude content of the data stream and inserts appropriate bit patterns to ensure that phase and amplitude lock are maintained on the data stream for reading and decoding purposes.

Abstract: A self-locking hub for a computer tape drive that uses tape tension along to actuate a tape reel torque lock. In a preferred embodiment of the invention, the torque provided by tape tension after tape is threaded from a supply reel to a take-up reel provides sufficient force to actuate an over-center, spring-tensioned engagement pawl-like hub lock mechanism that engages an inner surface of a tape reel with sufficient force to secure the reel to the hub. More than one such self-locking mechanism may be provided for a single hub to provide additional locking force. In an alternative embodiment, the self-locking engagement pawl can include an engagement flange that prevents a tape reel from being pulled off the hub or from falling off a vertically-oriented hub, thus providing additional security.