Method and apparatus for writing information on magnetic disk with single-gap magnetic head

An apparatus for writing information on a magnetic disk having a multiplicity of concentric recording tracks on a recording surface thereof, each of said recording tracks having at least one sector each including a sector-identification field storing sector identification data identifying each respective sector, each sector further including a data field on which the information is written, said apparatus comprising:

• a disk-drive device for rotating said magnetic disk;
• a single-gap magnetic head for writing, reading and erasing information on a selected one of said multiplicity of recording tracks;
• a head-positioning device for moving said magnetic head along the recording surface of said magnetic disk in a substantially radial direction of the disk;
• head-position control means for controlling said head-positioning device, to position said magnetic head at a centerline of said selected track, at a first erase position of said selected track which is displaced from said centerline of the selected track by a predetermined distance in one of radially inward and outward directions of the disk, and at a second erase position of said selected track which is displaced from said centerline by a predetermined distance in the other of said radially inward and outward directions;
• and
• erase/write control means connected to said disk-drive device, said magnetic head and said head-position control means, operable for (a) activating said magnetic head in said first erase position, to perform a first erasing operation on the data field of a selected one of said at least one sector of said selected track, after the sector-identification field of said selected sector has passed said magnetic head, (b) activating said magnetic head in said second erase position, to perform a second erasing operation on the data field of said selected sector, after the sector-identification field of said selected sector has passed said magnetic head, and (c) activating said magnetic head at said centerline of the selected track, to write said information on the erased data field of said selected sector, after the sector-identification field of said selected sector has passed said magnetic head.