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: 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 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 storage file for particular use with a flexible magnetic disk having a series of concentric magnetic tracks thereon, comprising a four phase stepping motor for moving a transducer head radially of the magnetic disk. The stepping motor has several sets of first, second, third and fourth phase windings arranged sequentially in the order named. A radial drive control circuit is provided which normally acts to cause energization of the stepping motor windings in a single phase drive mode to cause rotation of the rotor by discrete increments. In order to prevent the rotor from being trapped in alignment with the third phase windings, instead of being returned to the first phase windings, when the disk file is electrically turned on, the radial drive control circuit further functions to briefly energize a selected one or more of the second, third and fourth phase windings of each set, with the simultaneous or subsequent energization of the first phase windings.

Abstract: Several data storage devices for use with flexible magnetic disks are daisy chained to a central processing unit via a controller to be selectively driven thereby for data transfer with the magnetic disks. Each storage device has a motor control circuit for setting the magnetic disk into rotation when a corresponding DRIVE SELECT signal from the controller assumes a prescribed state for the first time after and IN USE signal common to all the storage devices has assumed a prescribed state. Further the motor control circuits sets the magnetic disk out of rotation when the DRIVE SELECT signal assumes the prescribed state for the first time after the IN USE signal has been set out of the prescribed state. Thus the storage devices are held out of operation to avoid unnecessary power consumption even after the production of the IN USE signal, until the associated DRIVE SELECT signals are applied.