Abstract: In a magneto-optical recording apparatus, a magnetic head is employed so as to perform vertical, or perpendicular magnetic recording. The magnetic head is constructed of a slider and a plurality of magnetic cores symmetrically positioned with respect to an axis of a magnetic recording medium. Each of the magnetic cores includes a main core, a return path core, and a gap.

Abstract: An improved method of managing media defects in disk drives keeps an operating list of the tracks in the disk drive, and for each track enters on the list the number of good sectors (i.e., those free of defects) in that track. Thus the information on the operating list is sufficient for the disk drive microprocessor to avoid use of the defective sectors, each of which is labelled in its header as being defective. This method is compatible with SCSI and other common disk drive interfaces.

Abstract: An optical integrated circuit and an optical apparatus used in optical communication or an opto-electronics apparatus such as an optical disk recording apparatus, in which various kinds of aberration caused by wavelength variation of a light source when a semiconductor laser is used as the light source. An aberration correcting grating having such grating pitches as to nearly satisfy the Bragg condition preferably with respect to a certain wavelength of the semiconductor laser beam is used. As a result, lowering of incidence (entrance) and radiation (exit) coupling efficiencies of the grating coupler and aberration such as chromatic aberration can be prevented. Even if a multi-mode semiconductor laser is used as a light source, the characteristics of the optical integrated circuit and optical apparatus do not vary largely.

Abstract: A data recording and reproducing circuit for a memory system, such as a magnetic disk memory system. The circuit includes a reflection type cosine equalizer and a data reproducing circuit. The equalizer includes a first equalizing circuit, having a first equalizing gain, and outputting a first equalized signal, and a second equalizing circuit having a second equalizing gain smaller than the first equalizing gain, and outputting a second equalizing circuit. The data reproducing circuit includes a differentiator for differentiating the first equalized signal, a window generating circuit for generating a window signal from the second equalized signal, and a data separator for discriminating the differentiated signal in response to the window signal to produce a pulsed reproduction signal.

Abstract: An apparatus for reading information performing a coarse adjustment of the time base by means of a phase difference between a reproduced sync signal obtained from a read signal read from a recording medium and a reference sync signal and performing a fine adjustment of the time base by writing data obtained by sampling the read signal according to a write clock signal being obtained based on the reproduced sync signal into a memory sequentially from a predetermined address according to a write count starting signal being in synchronism with the reproduced sync signal, and subsequently, reading out the data sequentially from the predetermined address according to a read count starting signal being in synchronism with a spindle reference signal whose phase is changed according to a jump command, in which it is adapted such that, when the time interval between generation of either one of the write count starting signal and the read count starting signal and generation of the other one becomes less than a predete

Abstract: In a system for recording digital data obtained based on an information signal on a magnetic tape and/or reproducing digital data obtained based on an information signal from a magnetic tape, a magnetic recording apparatus comprises an encoder for producing, based on the information signal, one of plural kinds of digital data which have different transmission rates respectively, a time base processor for selectively converting a time base of digital data obtained from the encoder so as to produce modified digital data having a predetermined transmission rate, a recording modulator for producing a recording signal corresponding to the modified digital data, a recording portion provided with a rotary magnetic head device to which the recording signal is supplied and a tape guide for guiding the magnetic tape and operative to cause the rotary magnetic head device to contact with the magnetic tape for forming oblique record tracks on the magnetic tape, a head driver for rotating the rotary magnetic head device at

Abstract: When data are memorized in a 2-7 RLL code on a disc shaped memorizing medium using a sector format, as an address mark in each sector a 2-7 illegal pattern is used; a 1-byte data "8B" in an NRZ signal is converted into a 2-7 RLL code, and further it is modified into the 2-7 illegal pattern.A disc controller in a disc memory inserts the 1-byte data "8B" into a specified position in an NRZ signal and transmits it to an encoder/decoder. In the encoder, the 1-byte data "8B" in an NRZ signal is detected, and a 2-7 illegal pattern is formed by reversing a specified bit of a 2-7 RLL code formed by converting the 1-byte data "8B", and the illegal pattern is sent to the read/write amplifier.

Abstract: Techniques for certifying recording sites (bit sites) on magnetic recording disks wherein test recording patterns are recorded along disk tracks: first in an analog mode, then in a digital mode; concluding in a full digital test that simulates customer operation.

Abstract: An adaptive prewrite compensation apparatus for writing data flux transition data on a magnetic medium, the apparatus incorporated in a disk drive assembly. A serial data pattern is introduced into the apparatus from a drive interface in digital form and is encoded. A combination of a transducing head and a writing location used for writing the data pattern on the magnetic medium is determined by the assembly. A predetermined write delay value based on the combination and the data pattern is computed by the assembly which then writes the data pattern on the magnetic medium with reference to the write delay value so that when the data pattern is read back, the flux transitions are preceived to be at the same distance as when entered into the apparatus.

Abstract: A system is provided for reproducing digital audio data from a recording medium on which segments of digital audio data are recorded with video data, with three segments of the digital audio data corresponding to one field of the video data, each segment including plural samples of the digital audio data, the number of the samples in four out of every five fields being different from that of remaining one of such five fields, and each segment further including identification data indicating field numbers to which each segment belongs. The system detects the identification data in each segment of the digital audio data and whether or not an error appears in the identification data, whereupon, numbering data 1 through 15 (=3.times.5) are derived from the identification data for indicating the phase of each segment in a set corresponding to the periods of the 5 fields.