Overland Data, Inc.

Overland Storage, Inc.

Cipher Data Products, Inc.

Other

Martin D Gray

William M Barton, Jr

The present invention comprises a magnetic recording system including a partial response, maximum likelihood recording channel incorporating fixed frequency read signal sampling and a digital timing control loop. Such a system is especially suitable in magnetic tape recording systems having a high degree of media speed variation during the read and write processes.

Magnetic tape drive apparatus including a variable rate encoder

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.

Write format for digital data storage

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.

Digital data recording channel

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.

Magnetic media having partitioned and presaturated data tracks

Method and system for controlling the position of a magnetic read head

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.

Automated tape cartridge library with accelerated calibration

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.

Variable rate bit inserter for digital data storage

A bit insertion apparatus and method used to error encode data stored on data storage media monitors the number of bit insertions made on a given randomized block of data to determine if the number of bit insertions falls within the tolerable limits for storing the data. If the number of bit insertions is not tolerable, the pseudo-random code used to randomize the data stream is reconfigured. 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.

Randomizing encoder for digital data storage

A magnetic tape drive capable of simulating the performance of a fast acceleration start/stop tape drive without a capstan drive or vacuum columns. A streaming type tape drive is provided with a semiconductor cache memory for storing data which may be written on, and data read from, a length of magnetic tape. Circuitry, including a microprocessor, DMA controller and service requests, handles data transfer between a host and the tape via the cache memory so that delays due to tape accelerations and decelerations are masked and the host can instantaneously read data bi-directionally and instantaneously switch between read and write operations.

Capstanless magnetic tape drive with electronic equivalent to length of

The disclosed apparatus includes a hollow column for receiving a loop of magnetic tape. A slot runs along the length of this column. A rigid conductive strip lies spaced apart from and parallel to the slot; and a flexible conductive strip lies between the rigid conductive strip and the slot. The two conductive strips form the plates of a variable capacitor. A vacuum is generated in the portion of the column lying beneath the magnetic tape loop to force a corresponding portion of the flexible conductive strip against the perimeter of the slot. Further, a partial vacuum is generated at the outside of the column near the conductive strips to force the portion of the flexible conductive strip lying above the tape loop against the rigid conductive strip. Air escape passages are included in the rigid conductive strip. As the two strips are forced together, any air lying therebetween instantaneously escapes through the passages. This substantially decreases errors between tape position and instantaneous capacitance between the plates.

Tape position sensing apparatus for magnetic tape drive

The disclosed apparatus includes a cylindrical shaped surface that synchronously rotates with a tape reel. Reflective material is patterned on this surface to form first, second and third tracks of bits running parallel to each other around the surface. A pair of light beams are aligned with the first and second tracks when a file protect reel is inserted in the tape reel, whereas the same pair of light beams are aligned with the second and third tracks when the tape reel does not have a file protect ring inserted therein. A light sensing circuit converts the portion of the light beams that is reflected from the aligned tracks into a pair of logic signals representative thereof. When the tape is moving in a predetermined direction, another circuit sets a bit in response to the logic signals as an indicator of which tracks are aligned with the light beams. Subsequently, the logic signals and the bit are used to indicate the amount of tape that is unwound from or wound onto the tape reel.

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La Jolla, CA, United States of America

Martin D Gray