Abstract: A magnetic tape cartridge includes a non-volatile semiconductor memory storing either a portion of the same data as that to be written to the tape or at least control data sufficient to recover from a delaying tape drive operation or from a mechanical failure in the tape drive thereby permitting signaling to a central processing unit an assurance that the data transferring by the CPU will be correctly written onto the tape. The host data can be directly transferred to the cartridge memory if the cartridge memory is fast enough and large enough to handle the transfer. An intermediate high speed non-volatile memory in the drive is necessary if the cartridge memory is too slow to handle the direct transfer or too small to handle the data transferred by the CPU. The cartridge memory then will contain command data sufficient to control the transfer of the data from the non-volatile drive memory to the tape.

Abstract: In a mass storage library, a module storage array includes a back plate having apertures patterned to form a cartridge storage together with cell blocks that mate with the openings in the back plate. A column of cell blocks are held in place between a shelf and a spring load and include calibration targets to align the cell blocks to the library accessor and reader. One stripe the length of the storage cell stack contains a bar-code. The bar-code extends the entire length of the stripe and identifies the individual cell blocks when empty. A plurality of columns of cell blocks provide the complete storage array. Each column of the cell blocks include one stripe with a bar-code along its length that is directly fastened to the back plate with each cell of the column having a separate bar-coding on the strip. The accessor includes a sensor that reads the coding to provide an indication of an empty cell block.

Abstract: In a mass storage library, an input/output station for inserting cartridges into and out of the library includes a door pivotally mounted to the station through cams that pivotally rotate a toggle bracket having fingers, one for each cartridge cell in the input/output station. Each cartridge used at least in the input/output station includes a cartridge orientation indicator in the form of a recess at one top edge of each cartridge. After inserting the cartridges into the cells of the input/output station, the door is closed rotating the toggle bracket and its fingers into the recess of each cartridge. The door will close if all of the cartridges have the recess correctly oriented to permit the fingers to clear the cartridges.

Abstract: In an automated retrieval library with virtual storage for identifying particular cartridges in the library to protect the data in the virtual volume from overwriting in import and export operations. A convenience input/output station is set to an import mode with export/import virtual tape servers. Possible import cartridges are categorized upon insertion to prevent their access by the host computer. Recovery from erroneous identification is provided.

Abstract: Commutators on a direct current motor run at low speed for an extended period of time get covered with a coating that makes the interface between the commutator and the brushes unreliable especially with the low speed, low current operation. This is especially true for drive motors in a data processing tape drive unit where speed control is critical. The brush to commutator interface can be cleaned by applying a very high electrical current to the motor and varying the polarity of the current with a variable duty cycle to obtain the maximum cleaning currents in a relatively short time without dismantling the motors.

Abstract: A plurality of parallel 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. A data integrity system provides a Cyclic Redundancy Check on the data before and after each section of the process. The compacted data is decompacted immediately after compaction as a read back check to verify that the compacted data can be reconstructed when retrieved.

Abstract: Format compatibility between arithmetic binary compression coding devices used in a magnetic tape drive can be retained even though different numbers of compression/decompression devices are required to attain a higher throughput through the system. Each device must process the data directed to it in a known maximum amount of time. Each compaction processor contains a selected number of statistic tables for each compaction processors. Eight compaction processors are selected with the possibility of two statistic tables in each. Thus format compability can be retained using four compaction processor with two statistic tables in each or double the throughput by using eight compaction processors with one statistic table in each encoder/decoder. Data compacted on a magnetic tape using either speed compaction can be decoded by either tape drive and compatibility is insured.

Abstract: A tape drive system includes a compaction scheme whereby the data to be stored on the media is encoded and formatted to take less space along the tape length. The data to be written to tape is placed into equal byte lengths or sets. The sets of data are directed to a plurality of encoders in turn and compacted through an Arithmetic Binary Coding program having two statistic tables per encoder to allow format compatibility with a higher throughput compaction scheme. The compacted sets are sequenced and formed into packets. Then the packets are autoblocked to delineate the packets while providing a single Inter Block Gap per autoblock length and written on the tape. On read, the data is retrieved from the tape and deblocked to separate the packets. Each packet is separated into compacted sets of data. The compacted sets are directed to a plurality of decoders in turn and decompacted. The decompacted sets are to resequenced to place the data into the same state as originally transmitted.

Abstract: A magnetoresistive (MR) sensor is center tapped to provide the difference signals for servo operation on data and sum signals for the data information. The center-tap of the MR sensor is made of a high resistivity material compared to the resistivity of the MR element itself such as tantalum, Nichrome and carbon. Processes which can be used to produce the high resistivity center-tap conductor include an insulator layer to define both the track width and the center-tap conductor and a sequence which first patterns the MR sensor and then masks to define the conductor regions.

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: A low magnetic isolation closure glass for use in multitrack magnetic tape heads has been prepared by combining a specific lead borosilicate glass with a specific borosilicate glass in a 60/40 weight percent ratio. The glass formed from the combination exhibits compatibility with ferrite and has reduced wear. Controlling the anneal temperature regulates the residual stress of the closure glass produced, and thus, provides some control over the wear characteristics of the glass.

Abstract: An optical analyzer for determining changes of the polarization plane in a light beam (4) comprises a substrate (20) supporting a photodetector array (21) and a system of imaging mirrors (22-24) underneath a parallel plate (25) of high-quality optical glass. The lower surface of the glass plate is covered by a system (26) of dielectric multilayers which acts as a polarizing beam splitter over a large range of angles of incidence. The optical beam (4) enters the analyzer through the glass plate to impinge under an oblique angle of incidence on a first mirror (24) which rotates the plane of polarization in the beam by 45 degrees with respect to the polarizing beam splitter, which then generates two beams partial (202,203) to be eventually directed to photodetector array (21). The beam analyzer is used in magneto-optical storage system to extract an information signal and to generate servo control signals for the focus and track positions of the beam.

Abstract: The disclosure relates to demotion of data to a backing store (disk storage apparatus--DASD) from a random access cache in a peripheral data storage system. A cache replacement control list, such as a least recently used (LRU) list is scanned in a soon-to-be replaced first portion (portion closest to LRU entry) to identify first data to be demoted. Then the control list is scanned in first and second portions to identify further data to be demoted with the first data as a single group of data. In DASD, such data is all storable in the same cylinder of the DASD.

Abstract: In a multiunit data processing system, such as a multicontrol unit peripheral data storage system, a least busy one of the units requests work to be done from a busier unit. The busier unit, a work sending unit, supplies work to the work requesting or least busy unit. Work thresholds in the respective units determine when work is to be requested or transferred. In a data storage environment, the transferred work consists of data transfers to be achieved usually asynchronously to connected host activities, such as data transfers between a backing and a front store in a data storage hierarchy.

Abstract: In a mass storage system having a multiplicity of storage volumes containing addressable data, the assignment of newly received data sets to the best storage volume is accomplished by determining the best match of the data set to the available volumes. Such selection enables maximum storage use of each volume. The best volume is one that provides memory space efficiency for the job at hand, and considers the volume life expectancy, the numbers of users, the shareability of the volume, and the status of the volume. First, all eligible volumes are listed. Then these volumes are sorted according to each volume's match and risk factors to the data set to be stored. The best fitting volumes are selected first for the actual data transfer and storage operation.

Abstract: A linear motor actuator particularly adaptable to position a magnetic transducer in a magnetic disk storage system including a modular stator assembly and a modular carriage assembly. The stator assembly includes a frame with a first pair of spaced parallel guide rails; configured to have two flat guide surfaces adjacent to the carriage assembly and running in a direction parallel to the stroke of the actuator. A magnetic flux return path is integrally connected with a guide shaft and positioned between the guide rails. The carriage assembly includes a self supporting cantilevered coil positioned about the return path and guide rail, and offset from the flat surface. The carriage assembly is supported by a first set of angled ball bearings which ride on the guide shaft and a second set of spaced ball bearings which ride on the guide rails to preload the carriage assembly and prevent rotation.

Abstract: Non-continuous forms are welded on an automatic device using a continuous welding process (e.g., Tungsten Inert Gas Process (TIG) with a continuous welding arc. The noise level of the welding system is below that which is prescribed by the Operational Safety and Health Act (OSHA). The device includes apparatus for indexing and positioning the non-continuous forms relative to the welding electrode. The device further includes apparatus for chilling the non-continuous forms during the welding process, and apparatus for periodically shunting the welding arc away from the non-continuous forms so as to maintain a continuous welding arc.

Abstract: An MR head is disclosed in which the MR element is deposited onto a sapphire substrate with a particular crystallographic orientation and a sapphire closure piece also having a particular crystallographic orientation is used. The substrate has the MR element deposited onto either the {0001} or the {1120} plane with the {1100} plane being oriented as the wear surface. The closure piece has either the {1120} or the {0001} plane facing the MR material and the {1100} plane oriented as the wear surface.

Abstract: In a recorder having a transducer with a gap which coacts with a flexible medium to record and/or reproduce data, an endless groove is positioned on the transducer to circumscribe the gap.

Abstract: An electromagnetic transducer particularly of the magneto-resistive (MR) type is biased by an inductive circuit means and operates within the linear portion of its characteristic curve. The inductive circuit means is interconnected to the output terminals of said transducer. An amplifier means is connected to the output terminals of the transducer and the inductive circuit means. The amplifier means is also biased by the inductive circuit means. The biasing scheme is enhanced when a gyrator is used as the inductive circuit means.