Abstract: A magnetic disk drive of the type comprising at least one read/write head assembly having a read/write coil which is center-tapped to provide a pair of coil halves which are alternately excited during writing, and a write terminate resistor connected between the coil halves for preventing the flow of oscillatory current therethrough during writing. In order to electrically isolate the write terminate resistor from the read circuit also coupled to the opposite extremities of the read/write coil, alternating-current switches are connected between the write terminate resistor and the read/write coil so as to be away from the paths of write current through the coil. The alternating-current switches are rendered conductive only during writing.

Abstract: A circuit arrangement for a flexible magnetic disk drive having an index sensor for optically sensing an index hole defined eccentrically in the magnetic disk, with the index sensor putting out an electric index pulse of less than a predetermined duration each time it detects the index hole during the rotation of the magnetic disk. The index sensor is prone to put out invalid pulses of not less than the predetermined duration as a result of the displacement of the magnetic disk relative to the index sensor.

Abstract: A data transfer apparatus for use with a replaceable disklike record medium such as a flexible magnetic disk having data storage tracks thereon, comprising a disk drive motor for imparting rotation to the record medium, and a head transport motor for transporting a transducer head or heads radially of the record medium so as to enable the transducer head or heads to access the individual data storage tracks on the record medium for data transfer therewith. Also included is a control and drive circuit for controllably energizing the head transport motor. When the record medium is not loaded in the apparatus, the control and drive circuit holds the supply voltage of the head transport motor zero, or lwoer than its normal operating voltage for head transportation, for saving power.

Abstract: A data transfer apparatus for use with a replaceable disklike record medium such as a flexible magnetic disk having data storage tracks thereon, comprising a disk drive motor for imparting rotation to the record medium, and a head transport motor for transporting a transducer head or heads radially of the record medium so as to enable the transducer head or heads to access the individual data storage tracks on the record medium for data transfer therewith. Also included is a control and drive circuit for controllably energizing the head transport motor. When the disk drive motor is out of rotation, the control and drive circuit holds the supply voltage of the head transport motor zero, or lower than its normal operating voltage for head transportation, for saving power.

Abstract: An electric control system for an apparatus for writing and reading data on and from a flexible magnetic disk under the control of host equipment such as a central processor unit having an associated controller. The control system includes a time setting circuit responsive to stepping pulses, by which the magnetic head is transported from track to track on the disk, for determining an access time to be elapsed from the moment the head starts to be transported from any track on the disk to any other track thereon to the moment the head becomes stably positioned on the new track. Connected to the time setting circuit is an index pulse suppressor circuit which suppresses any index pulse, indicative of the rotation and angular position of the magnetic disk, that is generated during each access time and which permits the delivery to the host equipment of the subsequent index pulses that are generated after the lapse of the access time.

Abstract: A floppy disk drive (FDD) capable of data transfer with a track density of, typically, 96 tracks per inch (TPI) is adapted for rewriting on a floppy disk on which data has been written on concentric data tracks by a 48-TPI FDD. The data tracks, each with a width W1, are arranged with a pitch P1 on the disk. The 96-TPI FDD has a magnetic head assembly comprising a read/write head capable of providing a data track width W2 of 0.4 W1 to 0.6 W1, and a pair of tunnel erase heads each capable of providing an erase width of (W1-W2)/1 to (P1/2-W2). The opposite edge portions of each prewritten data track on the disk are erased by the erase heads of the head assembly, with the latter successively positioned intermediate the data tracks.

Abstract: A double capacity adapter circuit is connected between host equipment and one or more magnetic disk drives in order to adapt the host equipment, which has been programmed for use with relatively small capacity magnetic disks, for use with double capacity magnetic disks in the disk drives coupled thereto. As originally programmed, the host equipment formats one side of a small capacity magnetic disk with first format data in response to an index pulse from the associated disk drive, and the other side of the small capacity magnetic disk with second format data in response to another index pulse. In order to format the double capacity magnetic disks with the same program, the adapter circuit delays the index pulses by a time corresponding to half a revolution of the magnetic disk, thereby producing pseudo index pulses.

Abstract: A floppy disk drive which, together with one or more like devices, is daisy chained to host equipment comprising a central processor unit and an associated controller. Each disk drive comprises a disk motor for rotating a record disk under the control of a disk motor drive circuit, a head motor for incrementally moving a transducer head radially of the record disk under the control of a head motor drive circuit, and a read/write circuit for processing data read from, or to be written on, the record disk via the transducer head. The host equipment produces, among other control signals, a MOTOR ON signal for the on/off control of the disk motor via the disk motor drive circuit.

Abstract: In a stepping motor of the type having one or more sets of four phase windings on respective stator poles, with the four phase windings being excited sequentially to cause the rotation of a rotor having magnetic poles, a drive method and system are disclosed for stopping the rotor in exact angular positions required. Since the stator can less magnetically control the rotor when the latter is positioned with its magnetic poles in axact alignment with the stator poles, the stator windings are sequentially excited in such a manner that upon termination of the sequential excitation, the rotor comes to a stop in a position angularly displaced to a predetermined degree in a predetermined direction from a position of exact alignment with the stator poles. Basically, for stopping the rotor in such angular positions, at least two of the four phase windings are excited at a time with currents of predetermined different magnitudes.

Abstract: A magnetic disk drive is disclosed which has a disk drive motor for imparting rotation to a magnetic disk, and a head transport motor for transporting a transducer head or heads radially of the magnetic disk for track to track accessing. The disk drive motor and the head transport motor are fed from a common direct current supply terminal via first and second switching transistors, respectively, which independently control power delivery to the two motors for effectively saving power. A voltage regulating capacitor is connected only between ground and the output line of the first switching transistor for the disk drive motor. In order to prevent the flow of a surge current due to the voltage regulating capacitor upon conduction of the first switching transistor, a conduction retarder is provided which causes a gradual conduction through the first switching transistor in response to an actuating signal from host equipment controlling the disk drive.

Abstract: An information processing apparatus such as a computer of the class for office and home use is disclosed which employs a magnetic disk cartridge as an information storage medium, together with a disk drive assembly for information transfer with the disk cartridge. The apparatus has a housing having defined therein a disk drive compartment, in which there is accommodated the disk drive assembly inclusive of its own enclosure having an entrance slot for the insertion of the disk cartridge. Upon full insertion of the disk drive assembly into the disk drive compartment, the disk drive assembly is locked into position by a locking lever which, under the influence of a cantilever spring, engages a first opening in the disk drive assembly.

Abstract: A flexible magnetic disk drive is disclosed which has a disk drive motor for imparting rotation to the magnetic disk under the control of a "motor on" signal, and a stepping motor capable of stepwise rotation in response to stepping pulses for transporting a transducer head or heads radially of the magnetic disk for track to track accessing. Connected to the transducer heads for processing data transferred between them and the magnetic disk, a read/write circuit is connected to a supply terminal via a switching transistor. This switching transistor has connected to its base a switch control circuit for holding the switching transistor nonconductive when the disk drive motor is out of rotation and when the stepping motor is in rotation, and for holding the transistor conductive at least during the progress of data transfer between the transducer heads and the magnetic disk.

Abstract: An apparatus for data transfer with a magnetic disk having a metal made hub attached centrally thereto, with the hub having a first opening defined centrally therein and a second opening defined eccentrically therein. The apparatus includes a turntable mounted on a drive spindle which is engageable in the first opening in the hub of the magnetic disk loaded on the turntable. A retractable drive pin is mounted eccentrically on the turntable so as to be sprung into engagement in the second opening in the disk hub upon register therewith. In order to assure engagement of the drive pin in the second opening in the disk hub immediately upon loading of the magnetic disk on the turntable, a disk drive motor for driving the turntable via the drive spindle is connected to a supply terminal via a power control switch.

Abstract: A drive method and system are disclosed for a stepping motor typically having several sets of four phase windings on respective stator poles of annular arrangement, and a rotor having several alternating N and S poles at constant circumferential spacings. Normally, the windings are sequentially excited as by a single or two phase drive mode to cause the rotor to rotate by increments. For stopping the rotor in a required angular position, any one or two of the four phase windings are excited in a normal direction to polarize the associated stator pole or poles into one polarity to attract one of the opposite poles of the rotor. Further, the other phase windings on both sides of the noted one or two windings are excited in the reverse direction, as by the discharge of capacitors, with the consequent polarization of the associated stator poles into the opposite polarity.

Abstract: An apparatus for data transfer with a magnetic disk having a diameter of, say, 86 millimeters, having a pair of transducer heads for data transfer engagement with the opposite surfaces of the disk mounted on a turntable driven directly by a disk drive motor. In order to hold the magnetic disk exactly level on the turntable for proper data transfer contact with the transducer heads, a leveling mechanism is provided whereby at least the turntable is made adjustably movable in its axial direction with respect to the frame of the apparatus, as by the manual turn of an adjusting screw or screws. In one embodiment, the turntable is movable with a drive spindle on which it is mounted coaxially and which forms an output shaft of the disk drive motor. In another embodiment, the turntable travels with the complete disk drive motor.

Abstract: A data transfer apparatus is disclosed as typified by a floppy disk drive which, together with one or more like devices, is daisy chained to a central processor unit via a controller. Each disk drive comprises a disk motor for driving a record disk under the control of a disk motor drive circuit, a head motor for incrementally moving a transducer head radially of the record disk under the control of a head motor drive circuit, and a read/write circuit for processing data read from, or to be written on, the record disk via the transducer head. Also included in each disk drive is a sensor control circuit associated with an optical sensor assembly for producing a DISK PRESENCE signal representative of the presence or absence of the record disk in the disk drive.

Abstract: A data transfer apparatus is disclosed as exemplified by a floppy disk drive which has photoelectric sensors such as a TRACK ZERO sensor for sensing whether a transducer head or heads are in the "track zero" position on the floppy disk, and a FILE PROTECT sensor for sensing whether the disk is protected against erasure of any prerecorded data. In order to avoid waste of power, at least the TRACK ZERO sensor, preferably the FILE PROTECT sensor as well, has its light source such as an LED connected to a power supply via a power saving switch herein shown as a switching transistor. Connected to the base of the power saving transistor is a switch control circuit which causes conduction through the transistor, and hence the energization of the sensor light source, only when the operation of the sensor is required, as for a preassigned length of time immediately after the apparatus is electrically turned on.

Abstract: A video disc player for use with a record disc having recorded along a spiral track thereon a succession of information streams to be reproduced and a series of addresses identifying the successive turns of the track. Also recorded on the record disc, prior to the information streams, is an index listing at least the starting addresses of the information streams. An optical pickup assembly reads the record disc by traveling in its radial direction in step with the rotation of the disc. A memory stores the index read from the record disc and, upon actuation of one of information selector switches by the operator, delivers the starting address of the selected information stream to a comparator circuit. During the subsequent process of access to the selected information stream, perhaps with the pickup assembly fed at high speed toward same, the comparator circuit receives another input representing that address on the record disc which corresponds to the position of the pickup assembly relative to the disc.