Abstract: Access time is improved in a automated library system having sequentially stored data on a recording tape medium. A multiplicity of copies of the data is stored on different tape cartridges. The copies and the original are stored in different areas of the library. Each data segment stored on the tape media copy is stored in different areas of the media length from the original. The multiple copies are created and deleted independent of any user control. The usage of the original and any copies determine the number of copies and their residence times. The library manager selects the tape cartridge that can be retrieved in the shortest response time using the location of the original and the copies, the location on each cartridge of the data requested, the drive and library robot picker availability and the respective queues.

Abstract: A system uses prevent and detect mechanisms to enable rewritable data storage media to be operated as a written-once-only media. A physical indication of the media casing serves as an indicator of the write-once-only status of the media. A watermark is magnetically recorded on the media at the factory with a portion of the mark detectable by the system and a portion only detectable by returning to an inspection station for verification. This protects against a complete erasure of all data from the media. A segment write status indication serves to indicate the write-once-only status of each segment of the written data. A portion of the written region, such as the preamble or control field of each segment, contains a status mark written randomly within the area as a status indication that the data was written once or multiple times within that segment.

Abstract: A plurality of parallel processing devices such as compression/decompression units can be tied together to sequentially process equal amounts or sets of data from a stream of data. Hardware in the upper level of each device acts as a demultiplexer to control the acceptance of only its set of data to transfer control to permit the next device to accept data and also stores its set for compaction. Essentially identical hardware in the lower half of each device acts as a multiplexer to control the acceptance of its compacted set of data to store the compacted set and to place the compacted set into the original sequence of the stream of data for storage on the tape media. The lower half reverses its role when the compacted set of data is retrieved from the media to act as a demultiplexer for the decode sequence while the upper half acts as a multiplexer to resequence the decompacted sets into its original stream.

Abstract: A thin film magnetic head and a method for making the thin film head by the use of electrical lapping guides includes the use of a resistive lapping guide that has a height dimension and an electrical resistance that optimizes the results of the comparison of the resistive lapping guide to a finished lapping guide. The resistive lapping guide is not lapped during the lapping process. The finished lapping guide is lapped and the resistive comparison between the two determines the stopping of the lapping process. An as-lapped guide which is of the same dimensions as the finished lapping guide after lapping can also be included. An interleaved magnetic head having alternating magneto-resistive read elements and inductive write elements can be precisely lapped by sensing the resistance of the lapping guide elements and using a formula to determine the final resistance of the finished lapping guide to halt the lapping process.

Abstract: An interleaved bi-directional magentic tape head for contact recording can have a poletip enhanced by providing a thin film of a soft magnetic material deposited onto a magnetic ferrite substrate. The second pole piece is a thin film of the soft magnetic material. A closure block of a non-magnetic ceramic encloses the layers together with leveling insulation layers and a deposited activating conductor turns. The stripe poletip deposited onto the magnetic ferrite extends for a distance just short of the first conductor turn and provides a balancing of the saturation moment of the pole pieces and provides for better recording capability, especially when operating in a trailing magnetic ferrite mode.

Abstract: The amount of tape wound on the hub of a reel can be determined by the tape drive by using a force/acceleration relationship. An electrical power which provides a certain torque to the motor is applied to the reel drive. The torque imparts a fixed rotational displacement over a fixed period of time. The rotational displacement is measured by a tachometer. The angular acceleration of different inertias results in different rotational displacement over the set period of time which can be used to indicate the amount of tape on the reel since the inertia of the other items, the motor, the clutch and the hub, remains the same.

Abstract: Fluid is introduced under pressure to the operative face of a magnetic head to lift the magnetic media out of contact with the transducers when the media is stationary or about to be stopped. The media is lifted only locally with respect to the multiple transducers of the magnetic head. The fluid pressure tents the tape with the pressure adjusted such that the media forms a seal with the head at the edges of the media to hold the fluid within the tent-like structure. Slots formed in the magnetic head at the leading and trailing edges allow the fluid to escape to keep the media from excessively lifting from the magnetic head. The fluid pressure is under control of a valve that introduces the pressure to the operative face of the head as well as opening the operative face to atmospheric pressure when the fluid pressure is halted to permit the media tension to quickly pull the media back into contact with the transducers by assisting the slots in dissipating the fluid pressure.

Abstract: A single reel magnetic tape cartridge includes a leader block for interfacing with an automatic threading system in a tape drive. The leader block has a slot in its leading surface that precedes an enlarged receiving cavity. The cavity and slot interface with a coupling device in a positive connection to unwind the tape from the reel into the tape drive.

Abstract: A manufacturing process for making a finer ferrite powder which can then be used to make a very dense block of the ferrite ceramic. The process for making the powder includes the steps of co-precipitation of an aqueous solution of metal ions and an ammonium oxalate solution. The co-precipitation particles are separated, washed and dried. The particles are low-temperature calcined and then vibro-energy or ball milled and dried. The particles are fluffed and broken up in a blender and pressed into a mold for sintering and pressing in a hot isostatic press procedure. The ferrite blocks are then post annealed in an oxygen atmosphere and cooled to form a dense magnetic ceramic particle. Preferably the process is for use in the production of nickel-zinc ferrite used for magnetic heads.

Abstract: A plurality of flangeless reel hubs store webs of a flexible material from a slitting operation. To quickly remove the filled reels from the individual clutch members, the inner driven diameter of the hub of the reel includes elongated diamond-shaped teeth. These teeth match with slots in the individual driving clutches. The teeth are centered and driven by the shaped slots which align and positively drive the reel. Relief cutouts are provided to accommodate the compression pressure against the hub by the many layers of web material wound under high tension onto the outer circumference of the reel hub. A single shaft with slots to match the teeth in the reel can be used to align the reels, and individual vacuum columns can accommodate the tension differences between the individual webs.

Abstract: A single reel tape cartridge is disclosed for an automatic threading tape drive. The reel includes layers of magnetic tape with a leader block attached to the free end of the tape. The leader block is held in a receiving well in one corner of the cartridge when the cartridge is out of a tape drive. The leader block interconnects with a threading pin in the drive for threading the tape through the drive to a take-up reel hub. The leader block includes conforming sections that fit the leader block into a U-shaped channel in the hub to provide a smooth hub periphery for the layers of tape.

Abstract: The sputter deposition of a thin film of material on both sides of a thin substrate is performed by positioning the substrate sides orthogonal to the target and preferably radial to the deposition center of the sputter system. The vapor deposition of alumina on a thin ferrite core for a magnetic head is accomplished by positioning the ferrite substrate in the vacuum chamber orthogonally to the target and radial to the particle deposition center. The alumina is deposited on both sides of the ferrite core simultaneously to substantially the same thickness. The deposition on both sides of the ferrite core protects the core against width erosion, and minimizes bending stress. In addition, signal output of the ferrite core when used in a magnetic head is increased.

Abstract: Diffusion bonding of dissimilar ceramics can be accomplished by the application of pressure only while the ceramics are at a temperature at which their expansion rates are the same. A process for manufacturing magnetic head cores is disclosed where a magnetic ferrite is diffusion bonded to a non-magnetic ceramic by heating the core pieces to the expansion rate crossover temperature and then applying the diffusion bonding pressure. The pressure is removed either before or after the bonded pieces are cooled.

Abstract: An automatic threading apparatus for a magnetic tape transport is disclosed using a constant force spring located outside of the plane of the tape path. A leader block attached to the free end of the tape from a cartridge is connected to a pick-up pin of the threading apparatus. The pick-up pin is attached to a spool that is connected to a constant force spring, sometimes known as a negator spring. The other end of the spring is connected to a hub which is located on a plane different from the take-up reel. A latch holds the spool with the spring adjacent to the supply reel. When the latch releases the spool, the spring on the spool will wind around the spool and pull the pick-up pin through a guide path such that the leader block is placed into the take-up spool and forms a part of the take-up hub to allow a desired smooth surface for the wraps of the tape around the hub.

Abstract: An automatic threading apparatus using a pantocam for a magnetic tape transport is disclosed. A leader block attached to the free end of the tape in a cartridge is connected to a pick-up pin attached to one end of a broken arm linkage. The broken arm linkage has its second end fastened to a rotatable shaft. The extension of the broken arm linkage is controlled by a follower link which includes a bearing that follows a cam groove. Rotating the broken arm linkage causes the tape from the cartridge to follow the tape path, such as a cucumvoluted path, in a sweeping motion past air bearing guides and a transducer into a take-up reel. The threading pin remains in contact with the leader block which forms a smooth surface for the tape with the take-up reel.

Abstract: Reels of magnetic tape used in a reel-to-reel drive system suffer from an inter-layer slip if the reel has gone through environmental changes. This slip will cause errors to occur in the reading of the tape, since a constant tension and velocity and an accurate position is required in the reel-to-reel drive. To check whether the tension of the tape needs to be refreshed, the end of the tape is firmly held while the hub is driven in a reverse direction against the firmly held end of the tape. A detected reverse rotation indicates an inter-layer slip condition. The tape tension must be refreshed by unreeling the tape and rereeling with the correct tension applied. The reel of tape is then ready for operation.

Abstract: A magnetic tape cartridge is disclosed in which a length of magnetic tape is wound on a single reel with the free end of the tape permanently connected to a generally rectangular-shaped leader block. The cartridge completely surrounds the reel of magnetic tape except for an opening provided at one corner of the cartridge. This opening permits tape wound on the reel to be unwound as the leader block is moved away from the cartridge, preferably by an automatic threading mechanism. The cartridge is characterized by one corner of the cartridge through which the tape passes being provided with a leader block receiving well in which the bottom of the well surface defines the opening in the cartridge through which the tape moves.

Abstract: This invention provides an improved method and apparatus for manufacturing magnetic recording media; specifically, that which is to be used in the manufacture of flexible, magnetic recording disks. The process provides a sequence of disorienting magnetic fields in different directions and of diminishing strengths to form a magnetic media in which the magnetic particles are essentially disoriented and the media is, thereby, devoid of modulated signal envelopes.