Magnetic disk memory track change servo

Claim 1

A disk control circuit for a magnetic disk apparatus comprising: a magnetic disk operably connected to said apparatus for storing data, including servo data on tracks; a carriage, operably connected to said apparatus for radial movement with respent to said magnetic disk; a first magnetic head operably connected to said carriage for reading data from and writing data to said magnetic disk; a second magnetic head, operably connected to said carriage, for reading said servo data; a motor operably connected to said carriage, for moving said carriage; motor driving circuit means, electrically connected to said motor, for driving said motor; convertor circuit means, electrically connected to said first head and said second head, for converting said servo data read out from said second head to a position signal to indicate the position of said first head with respect to said magnetic disk, to a speed signal to indicate the speed of said first head, and to a track pulse to indicate passing of said first head over a track of said magnetic disk; processing means, electrically connected to said converter circuit means, for generating target speed information, said target speed information corresponding to the distance between a target track and a track which said first head is positioned above whenever said data processor receives said track pulse, to control the speed of said first head, and for generating track offset information to control the position of said first head; a servo control register means, electrically connected to said processing means, for storing said track speed information and said track offset information from said processing means; a digital to analog convertor means, electrically connected to said servo control register means, for converting said track speed information and said track offset information from said servo control register means to analog signals; signal selecter means, electrically connected to said processing means, said convertor circuit means and said digital to analog convertor means, for selectively generating motor control signals based on predetermined combinations of said speed signal, said position signal and said analog signal from said digital to analog convertor; and a motor drive controller means, electrically connected to said signal selector means and said motor driving circuit means, for generating and coupling to said motor driving circuit means motor drive control signals in response to said motor control signals.