Abstract: An ultra small track width magnetic transducer and manufacturing method. The transducer has two coplanar confronting magnetic poles provided by a thin film layer of magnetic material. The thickness of the layer defines a track width. A transducing gap is etched in the magnetic layer by utilizing focused ion beam milling technology. The thusly obtained gap has a predetermined length and depth and it separates the magnetic layer into two confronting coplanar magnetic poles. A layer of non-magnetic material is deposited over the magnetic layer to fill the transducing gap. The transducing gap may be etched in a plane extending orthogonally to the plane of the magnetic core layer. Alternatively, the transducing gap plane may extend at an oblique angle to the magnetic core layer to obtain a transducing gap useful in aximuth recording/playback. A window in the magnetic layer interconnects conductor leads to form a transducer winding.

Abstract: A magnetic transducer has a transducing gap that is wider than that used for transferring information signals with respect to a magnetic record medium. A magnetic control flux is applied to the transducer to enable a selected segment of the transducing gap, which defines a transducing zone, for transferring information signals with respect to a selected path along the magnetic record medium. Registration of the transducing zone over the selected path is maintained by varying the applied magnetic control flux to thereby move the transducing zone along the wider transducing gap so as to compensate for deviations between the path traced by the transducing zone over the magnetic record medium and the selected path.

Abstract: An apparatus for controlling conditions in response to an operator input, the apparatus including a rotary knob coupled to the shaft of the rotor of a stepper motor having first and second stator windings, in quadrature, with each winding being center tap grounded to provide first and second winding portions for each winding. One pair of first winding portions are used for providing pulse inputs to a microprocessor on rotation of the knob, in either direction, via a pulse control system, with the microprocessor providing command signals to a braking control system, which includes a direct current power control source, which may be either a voltage or current control source. The power control source, in turn is in circuit relation with the pair of second winding portions.

Abstract: A symbol generator with pipeline architecture comprised of a series of processing stages that regenerate a complete video data signal for each display field. Any symbol in a display may be moved in real time and independently of any other symbol, because the display is regenerated for each and every field. The symbol generator includes a cpu microprocessor, vertical sorter, boundary generator, horizontal sorter, and color palette.

Abstract: An improved head mounting assembly includes a wedge-shaped rigid head support member which minimizes resonances when operating at rapid transverse head movements, and which operates in conjunction with a photo-sensitive head positioning apparatus, to provide improved tracking for a transducing head mounted on the member.

Abstract: Apparatus is described for coupling magnetic flux defining information between a first body of magnetic material and a second body of magnetic material having a magnetic flux path therein. A third body of magnetic material having a transducing zone is included and disposed to be magnetically proximate the first body of magnetic material to couple flux to or from the same, and to have a portion thereof magnetically proximate the magnetic flux path within the second body of magnetic material to provided coupling of flux to or from such flux path. In specific embodiments described, the first body of magnetic material is a magnetic storage medium such as a layer of hard magnetic material of a tape, and the second body of material is a transducer core of a soft magnetic material.

Abstract: An image data compression technique is described which utilizes calculating means and a selected series of bit calculating stages having delays, to estimate one or more quantization parameters for such data. The estimation process preferably is iterated a number of times, with the values found through each estimation being used as the trial values for subsequent estimations. In addition, an initial trial value is selected by a data look ahead technique, which assures that its value is within range of the final quantization parameter used to quantize the data. The final quantization parameter insures that the compressed data fits within a predetermined number of encoded data bits to be transmitted or recorded, for example, in a recording medium.

Abstract: A symbol generator that provides a video color signal that presents different colors for different portions of a symbol is illustrated herein. The symbol generator includes a number of separate stages that are connected in series to provide a processing pipeline. Elements for providing vertical color blends between the top of a symbol or selected background area and bottom of the symbol or background area are divided between the processing stages. Vertical color blending is achieved by mixing a difference color into a start color in an amount determined by the depth or displacement of consecutive raster lines from the top of the symbol.

Abstract: A magnetic transducer arrangement includes a core with a gap and a body of magnetically anisotropic material in which a signal transfer region is defined. Control flux flows across the gap of the core and through the body in opposite directions. The two oppositely directed flux flows influence one another and tend to cancel each other to define a null zone. This null zone, in which the flow of control flux is very low, is sensitive to flux emanating from an adjacent magnetic storage medium and therefore defines the signal transfer region. By varying the relative proportions of control flux flowing in the opposite directions, the location of the null zone can be varied along the width of the magnetic transducer to thereby scan the signal transfer region. The flux which is coupled from the magnetic storage medium into the null zone of the body does not flow through the magnetic core in a manner similar to a fringing flux.

Abstract: A slave device detecting system utilizes the past history of devices connected to a data bus to optimize the time required to re-establish communications. Whenever a master controller senses a condition that requires an assessment of devices on the bus, it examines the addresses of previously connected devices at more frequent time intervals than it does for addresses that were not previously associated with connected devices. In a preferred approach, all valid addresses can be examined in a sequential fashion, and the address of the previously connected device can be examined at every fifth or tenth position in the sequence. With such a technique, a device will be detected much faster once it has returned to the bus.

Abstract: An apparatus and method are provided for controlling the level of an audio output signal which has been recorded and is played back from a magnetic tape at a low or zero tape speed, such as utilized in jog mode or variable speed playback during editing. A gain control signal is provided to eliminate a disturbing repetitive audio signal which accompanies stop motion playback and to reduce that signal level at low tape speed playback. The gain control signal is made dependent on the magnitude of tape speed, and it is applied to adjust the audio output gain of the playback channel.

Abstract: An electromagnetically controlled scanning magnetic transducer has two magnetic core portions with confronting poles defining a transducing gap. A control winding is arranged in each core portion to provide a control flux therein. The control flux saturates a region of the transducer face of each core portion, adjacent to the gap. The saturated regions define adjacent unsaturated highly permeable regions which overlap at the gap to obtain a transducing zone. The transducing zone can be altered, moved, scanned or otherwise positioned along the transducer width by electromagnetically controlling the location and size of the saturated face regions.

Abstract: A scan tracking centering algorithm is not left at a nominal value, but is modified based on a tape timer's position into the field. That is, the scan tracking centering is adjusted forward (i.e., down) if the tape timer indicates the tape position is early in the field, and is adjusted back (i.e., up) if the indicated tape position is late in the field. Thus, the head deflection control decision which determines if the jumps, or doesn't jump, is made dependent upon tape position in the field, as well as on head elevation.

Abstract: The low frequency restorer of the invention restores the DC and low frequency contents to a digital signal which has been submitted to magnetic recording, playback and equalization processes. The restorer first provides a coarse representation of the originally recorded digital signal by clamping and subsequently hard limiting the equalized signal. The hard limited signal is then low pass filtered and the resulting signal, which is an approximation of the missing DC and low frequency components, is utilized as a correction signal, which is summed with the equalized signal, to restore the missing components. An alternative embodiment further eliminaes low frequency cross talk from the equalized signal by high pass filtering the equalized signal and low pass filtering the correction signal prior to summing.

Abstract: The decision feedback decoder of the invention receives sequentially sampled values of a signal waveform corresponding to data bits transmitted by a channel. A magnitude comparator compares the sampled values to a threshold and based on each comparison it provides subsequent decisions determining the values of the corresponding data bits. A predetermined number of previous decisions are stored and applied to a first and a second threshold adjustment circuit. Each circuit adjusts the threshold depending on the respective values of the previous decisions, while the first circuit provides the adjustment based on an assumption that the next decision to be made will have a first signal value and the second circuit provides the adjustment based on an assumption that the next decision will have a second signal value. When that next decision becomes available, it is utilized to select the correct adjusted threshold value for the next comparison by the magnitude comparator.

Abstract: In a digital tape recording system for video and sound signals, in which information in each track is stored in plural sectors having synchronizing preambles that aid in synchronizing the playback of the information, special preambles containing a frequency component that is lower than normal are used for the first sector of the first track in each video frame or field. The normal and special preambles are produced by passing the binary code". . . 01010101 . . . " (in the case of all but the first sector of each frame or field) or ". . . 011011011011 . . . " (in the case of the first sector) through a Miller Channel Code encoder to produce, in the first case, a synchronizing square wave fluctuating at one-fourth the bit presentation frequency, and in the second case, a synchronizing square wave fluctuating at one-sixth the bit presentation frequency.

Abstract: In a head displacement measuring apparatus, a folded optical path is used to introduce a collimated beam of light from a light source to a split photo detector, wherein both the light source and the split photo detector are mounted external of the support housing which secures and supports the flexible head assembly. A pair of optical prisms direct the light beam parallel to a head supporting blade integral with the head assembly. A Fresnel lens secured to the blade, preferably at the head end, varies the position of the path of the light beam in response to lateral displacement of the blade and head, to likewise vary the extent that the beam impinges one or the other of the photo detectors. The difference of the signals from the split photo detector provides a precise measurement of the transverse displacement of the head from a nominal centered position.

Abstract: To expand the interrupt capabilities of a microprocessor system without restructing system architecture, intermediate levels of priority are created for a given interrupt request. Plural interrupts can be handled on one interrupt request line to thereby permit execution of a number of functions that is greater than the number of interrupt lines. A system controller which provides this capabitlity can monitor the various functions during their execution, as well as arbitrate among plural interrupts so as to maintain the priority which has been assigned to them.

Abstract: A record current optimization technique includes a magnetic reference tape pre-recorded with a selected frequency at a precisely known level into the tape. A magnetic tape recorder is loaded with the reference tape, and a reference playback level is recovered from the reference tape with a playback head, and is stored or otherwise noted. A recording at the selected frequency then is made with a record head on an unrecorded portion of the reference tape. The new recording is simultaneously read out with the playback head and record current automatically or manually is adjusted until the new playback level matches the reference playback level. A value corresponding to this optimized record current is stored. The record head thus is optimized for any subsequent recording process, by selecting the stored value corresponding to this value. The optimization technique may be employed to optimize record currents in audio, video and data, analog or digital, recorders.

Abstract: Structures of magnetic heads having superconducting shields are disclosed for spatially directing magnetic recording/playback fields. One embodiment is a thin film magnetic head with a layer of superconductor material associated with its throat. Further embodiments provide intertrack shielding and concentration of recording/playback fields into relatively small pole tip regions.