Abstract: A seek control device for use in a floppy disk apparatus, for performing a reverse seek operation to detect the zero track position on a magnetic disk as a reference for moving the magnetic head to a destination track on the magnetic disk. The device includes a driving section for seeking the zero track position in response to an input reverse seek instruction and for seeking a destination track position in response to an input forward seek instruction, a track zero signal generating section for generating a track zero signal when the magnetic head is on the zero track, and a seek control section. The seek control section determines if a seek error has occurred, and in response, temporarily interrupts the input seek operation, generates forward drive instructions until the track zero detection signal has been turned off, generates a reverse drive instruction to the driving section in order to seek the zero track position, and then continues with the input seek operation.

Abstract: A floppy disk drive apparatus capable of using high- and low-density disks includes an erase section. When it is determined that a floppy disk to be used has a high-density, data is immediately written on the floppy disk in response to a write command. However, when it is determined that the floppy disk to be used has a low-density, data, which has previously been recorded on the recording area of the track where the read/write head is currently located, is erased prior to the writing of new data. After erasure is completed, the new data is recorded on the recording area, in response to a write signal.

Abstract: Disclosed is a self-compensating device for a magnetic disc apparatus with a velocity servo system in which an output signal of a velocity detector detects the velocity of a read/write transducer is automatically compensated by the combination of a control means and a compensator. While supplying a given velocity command signal to the velocity servo system, the control means measures the velocity of the transducer by using a track detector and adjusts the compensator on the basis of the result of the measurement.

Abstract: Disclosed is a self-compensating device for a magnetic disc apparatus with a velocity servo system in which a change of the characteristic of an actuator for positioning a read/write transducer is automatically compensated by the combination of a control means and a compensator. While supplying a given velocity command signal to the velocity servo system, the control means measures the motion of the transducer by using a track detector and adjusts the compensator on the basis of the result of the measurement.

Abstract: A servo track apparatus comprising at least one unit pattern area including 2n (n=2, 3, 4, . . . ) servo tracks T.sub.i (i=0, 1, . . . 2n-1) and 2n.sup.2 flux transitions R.sub.jk (j=0, 1, . . . 2n-1; k=0, 1, . . . n-1). The tracks and flux transitions satisfy a condition TT requiring that track T.sub.p be adjacent to track T.sub.p+1 ; a condition TR requiring that transition R.sub.pq occur on track T.sub.p+q (mod 2n); a condition RR requiring that transitions R.sub.pq and R.sub.pr (r.noteq.q) have the same polarity and occur at the same position; and a condition RR requiring that transitions R.sub.pr and R.sub.qr (q.noteq.p) occur at different positions.