Abstract: A user configurable RAID system designed to provide RAID functions as well as mass storage functions in a non-RAID mode. Flexibility is built into the system to allow the user to configure the SCSI bus to which removable drive modules are connected into one or more channels to define some of the drive modules in a RAID set and others as stand-alone drives which are independently operated or logically grouped and operated in a non-RAID mode. Removable internal SCSI bridges allow the SCSI bus to be configured into one or more channels. In the RAID mode, the system is configured to prevent a wrong drive from being removed from the system in the event of a drive failure. The system automatically unlatches only the failed drive. The RAID system includes an intelligent control unit ("ICU"), a RAID controller and a modem. The ICU allows the system administrator to access the RAID system Monitor Utility so that the status of the system may be monitored and its configuration changed.

Abstract: A magnetic storage system includes a magnetic storage medium comprising a keeper layer of relatively low permeability soft magnetic material deposited upon a magnetic storage layer or between multiple magnetic storage layers. The low permeability keeper layer may be disposed either above or below the magnetic storage layer. In the unsaturated state, the keeper layer acts as a shunt path for flux emanating from recorded transitions on the magnetic storage layer, producing an image field of the recorded transitions in the keeper. This shunt path prevents signal flux emanating from the recorded transitions from reaching the head. To read data from a recorded transition on the magnetic storage layer; a bias current is applied to windings of the head, creating a bias flux which saturates a portion of the keeper layer. Once saturated, this portion of the keeper can no longer shunt flux emanating from the recorded transition, which is the region represented by the head reproduce transducer.

Abstract: Improved magnetic tip designs attain low spacing loss and enhance the channel output signal while extending head life. One embodiment includes a relatively flat tape contacting surface whose outer edges are modified to provide a tape contacting surface of dumbbell or bow-tie shape, that is, a shape which is narrower at its center near the magnetic gap and wider at its front and rear ends. The desired shape for the tape contacting surface is attained by shaving or beveling the edges of the tip at a relatively sharp angle to remove more material along the top of the curvature of the head near the gap than at the front and rear of the tape contacting surface. This allows air to bleed from under the tape as the head tip travels past the tape. In another embodiment the desired shape is attained by polishing and/or grinding the edges of the tip at a controlled angle as small as 1.0 degree to remove sufficient material to create the desired bow-tie shaped tape contacting surface.

Abstract: The invention provides techniques for changing the quantization used in multiple generations of selected complexity of data quantization such that the errors incurred in subsequent generations are substantially the same as the error incurred in a generation given the same complexity of data. To this end, in a preferred embodiment, quantizing factors are selected from a preselected finite non-degenerative set of quantizing factors provided in the form of arrays of a periodic series of individual quantizer values, wherein a special numerical relationship is maintained between corresponding quantizer values in successive arrays. A different quantizing factor may be selected for each generation of compression/decompression as required by changing data complexity as when performing a layering process during the generations.

Abstract: A magnetic storage system is disclosed that includes a magnetic storage layer associated with a soft magnetic saturable keeper layer. A transducer is spaced from the storage layer and the keeper layer in flying relationship thereto, with an MR element contained therein to provide high sensitivity detection along with the reduced spacing loss available from the keepered storage layer.

Abstract: The flexible, particulate magnetic storage medium includes a substrate and a magnetic storage layer of hard magnetic particles held within a binder. The flexible, particulate magnetic storage medium also includes a soft magnetic keeper layer. The soft magnetic keeper layer may be established by coating the individual hard magnetic particles of the magnetic storage layer with a layer of soft magnetic material to establish a "keeper layer" around each particle. A break layer of non-magnetic material may be provided between the hard and soft layers. The individual particles are coated by methods such as in situ precipitation. The soft magnetic layer may also be established by providing a separate layer of soft magnetic material within a binder of cross linkable resins. The resulting flexible, particulate magnetic storage medium is a laminate principally comprising a substrate, a first layer of hard magnetic particles within a binder, and a second layer of soft magnetic particles also within a binder.

Abstract: A magnetic storage system includes a magnetic storage medium comprising a keeper layer of relatively low permeability soft magnetic material deposited upon a magnetic storage layer or between multiple magnetic storage layers. The low permeability keeper layer may be disposed either above or below the magnetic storage layer. In the unsaturated state, the keeper layer acts as a shunt path for flux emanating from recorded transitions on the magnetic storage layer, producing an image field of the recorded transitions in the keeper. This shunt path prevents signal flux emanating from the recorded transitions from reaching the head. To read data from a recorded transition on the magnetic storage layer, a bias current is applied to windings of the head, creating a bias flux which saturates a portion of the keeper layer. Once saturated, this portion of the keeper can no longer shunt flux emanating from the recorded transition, which is the region represented by the head reproduce transducer.

Abstract: A magnetic transducer is batch fabricated from a pair of confronting elongate composite block substrates each formed of a thin cap of non-magnetic material bonded to a much larger block of magnetic material, such as ferrite. An intermediate winding groove is formed in proximate relation to the non-magnetic material along the length of one or both composite block substrates. One (or both) of the substrates is provided with a plurality of parallel spaced V-shaped grooves oriented in a direction perpendicular to the winding groove, wherein adjacent grooves form therebetween track width defining lands. A core layer of high permeability magnetic material, such as Alfesil material, is deposited over the edges whereby magnetic poles are formed of the edges. A gap layer of insulating material is deposited on the edges over the high permeability magnetic material. Two of the composite block substrates are placed with the edges in aligned abutting relation and are assembled by glass bonding.

Abstract: In an azimuth recording format, the crosstalk of the A channel into the B channel is higher than the crosstalk of the B channel into the A channel because, at the ends of a magnetic recording where the switching contour of constant magnetic field strength is equal to the media magnetization switching field, the switching contour follows a curve. The resulting curvature at the ends of the magnetic recording vary accordingly the angle of azimuth rejection between the B to A azimuth relative to the A to B azimuth at the edges of the track. The use of a record head of a unique design wherein the trailing pole face of the head extends laterally beyond its leading pole face at the over-writing side of the head, removes the curvature at the ends of the transition recordings forming the recorded tracks.

Abstract: A flexural pantographic mount for use in a helical scan magnetic tape transport, the mount being a boxed leaf stiffened flexural pantograph mount, for holding and varying the position of a moveable head in a helical scan automatic scan tracking magnetic tape transport. The mount includes a moveable body such as a magnetic transducing head assembly coupled at one end of first and second generally parallel spaced apart elongated flexural pantographic leaves configured at the opposite free ends thereof for attachment to a fixed body. Each leaf includes first and second integrally formed and bent leaf edge extensions, which act as side stiffeners. A triangularly configured opening and a trapezoidally configured opening are formed in each leaf with each opening being configured to include tab projections for bending into the opening to provide transverse or lateral stiffening.

Abstract: A translatable capstan/tachometer assembly for use, for example, in transporting a magnetic media in a data record/reproduce apparatus, includes a capstan rotatably coupled to a tachometer unit. The assembly is supported for movement from an initial, unthreaded media position within a threading cavity of a data cassette, to a threaded or locked working position. The media path is arranged so that moving the capstan/tachometer assembly into the threaded position causes the media to wrap around the capstan with a substantial wrap angle. In play, record, jog or variable speed operational modes, movement is provided between a motor/disc assembly and the capstan/tachometer assembly to rotatably drive the capstan. In a high speed shuttle mode, the motor/disc assembly is disengaged but the capstan/tachometer assembly remains in contact with the media, thereby still providing tape speed information via the integral tachometer unit.

Abstract: A method and apparatus for data storage and retrieval including first and second banks of refreshable memory, such as DRAMs. The user application provides a write clock and a read clock, the read clock being independent of the write clock. FIFO buffers are provided between the user application and the memory, with the buffers providing for read data with associated addresses and write data with associated addresses. A DRAM controller system is provided including a timing generator for the DRAM controlled by an external clock. The controller system controls the buffers to enable the continuous writing of user data to one of the first and second banks at a given address, with the user address and data synchronized to the write clock, while enabling simultaneous reading of data at a user provided address from the other of the first and second banks, with the loading of read addresses and outputting of read data occurring continuously and synchronously to the read clock.

Abstract: A video special effects system and method includes at least one signal system operating in real time to transform one or more input video signals to generate an output video in response thereto, a work station, an operator control panel and a control system communicating with the signal systems, the work station and the control panel. Control surfaces defined by one or two control curves are developed at the work station and subsequent used by the control system to define a video effect in which portions of the input video images are selectively mapped to the control surfaces and subsequently manipulated to define an output video image. The control system operates to define each parameter controlling the output image at selected event times and to individually interpolate each given parameter between the event times at which the parameter is defined. The signal systems generate the output images in response to input images and the instantaneous values of control parameters defined by the control system.

Abstract: In a recorder/reproducer apparatus, a scanning magnetic transducer for the magnetic recording and reproducing of a data signal in a magnetic storage medium. The transducer includes one or more elongate main pole segments embedded in the periphery of a rotary drum and oriented at an angle relative to the drum's axis of rotation. An elongate stationary pole with an electromagnetic winding coupled to the data signal is spaced from the drum and oriented generally parallel to the axis of rotation. A magnetic tape is transported between the two poles in contact with the main pole segments on the drum and spaced from the stationary pole. Rotation of the drum during recording and/or playback causes the area of intersection, that is, the opposed common area or confronting face portions, of the stationary pole and each of the successive main pole segments to be moved or scanned along the face of the stationary pole.

Abstract: The presence and stability of the input digital video signal of a digital video device, such as a digital video tape recorder system, is determined by a system control microprocessor running a program for periodically reading signals from an input data clock presence detector circuit, a circuit detecting presence of timing reference code words in the input digital video signal, and circuits measuring rates of single-bit and multiple-bit errors in the detected timing reference code words. The input signal is determined present and stable if the input data clock is present, timing reference code words are present, and if measured sync data error rates do not exceed some experimentally determined threshold values.

Abstract: A low cost, high speed data storage system provides word-by-word stale data detection while avoiding the need to both read and write a single memory location during a memory read operation. Two flag data storage bits are provided for each word location in addition to the normal data storage bits. As blocks of data are received by the storage system one of the two flag bits is assigned to the block on an alternating basis. Upon writing data to an address location, an assigned flag bit is written to a first state to indicate valid data. When reading, the corresponding assigned flag bit is output as a stale or invalid data signal and the nonassigned flag bit is set to a second state different from the first state in preparation for the next block of data.

Abstract: A technique is provided for a color imaging system having a luminance component and two color difference (chrominance) components, which allots more space in the compressed data stream to the signal component of greater information content or complexity; that is, which combines the encoding of the components of the data representing a common portion of an image in response to the actual needs of the component, prior to encoding the combined data. To this end, the calculation of the quantizing factors considers the combined information content of both the luminance and chrominance components for the same image location. Thus, low chrominance complexity allows the transmission of more of the luminance information, and vice versa. The system also provides for predetermining the relative complexity of the signal components to thus pre-allot the amount of space for each signal component in the compressed data stream in proportion to its measured complexity.

Abstract: A transition overshoot of the record current is usual to compensate record head efficiency loss at high frequencies. Recording compatibility is achieved by decreasing the record current overshoot at the digital data signal transitions as the head gap depth decreases due to wear. Additionally, the different gap depth record heads of different head efficiencies require different optimum record current levels to provide maximum signal-to-noise ratio in the reproduced signal. The head gap depth thus is monitored by means of the optimum record current level without actually measuring the gap depth. The desired amount of overshoot is adaptively adjusted to the gap depth during the recording process by tracking the overshoot to the optimum record current level derived by adjusting the record drive level signal. Recording compatibility between different gap depth heads is achieved using the existing normal record current optimization process during recording.

Abstract: A two channel circuit and method for the automatic edit optimization of a recording medium which is operable with a recorder such as a video tape recorder or a disc recorder, utilizes a first channel means including an automatic scan tracking playback head and a second channel means including a record head. First and second rf peak signals indicative of variations in the stored data patterns in the medium are generated for the two channels. The gain of a variable gain amplifier coupled to the automatic scan tracking playback head is adjusted in accordance with a first correction signal derived from the generated first rf peak signal. The gain of a variable gain amplifier coupled to the record head is adjusted in accordance with a second correction signal derived from the generated second rf peak signal.

Abstract: A single channel circuit and method for the automatic edit optimization of a recording medium which is operable with a recorder such as a video tape recorder or a disc recorder utilizes the difference between signal outputs from an automatic scan tracking playback head and a record, head to provide a difference signal indicative of the rf amplitude fluctuations caused by scene or data pattern variations of the data stored on the recording medium. A correction signal corresponding to the difference signal is stored, and used as a feedback signal to normalize the gain of a variable gain amplifier. The single channel is switched at a predetermined rate between circuitry coupled to the automatic scan tracking playback head and circuitry coupled to the record head in order to obtain rf amplitude samples from both heads to develop the correction signal. Thereby, the correction signal allows a precise edit optimize so that a subsequent edit operation such as an insert edit can be precisely performed.