Abstract: A circuit provides a normalized position signal in response to a position of an illuminated spot on a lateral effect photosensor. The photosensor provides a concurrent pair of analog signals. The spot is illuminated by a light emitting diode. The circuit includes a summing circuit that provides a sum signal in response to an algebraic sum of the pair of signals, a first difference circuit that provides the position signal in response to the algebraic difference between the pair of signals, and a second difference circuit that provides an error signal in response to the algebraic difference between a reference signal and the sum signal. The error signal is coupled to the light emitting diode for governing an intensity of the spot, thereby normalizing the position signal.

Abstract: A circuit provides a normalized position signal in response to a position of an illuminated spot on a lateral effect photosensor. The photosensor provides a concurrent pair of analog signals. The spot is illuminated by a light emitting diode. The circuit includes a summing circuit that provides a sum signal in response to an algebraic sum of the pair of signals, a first difference circuit that provides the position signal in response to the algebraic difference between the pair of signals, and a second difference circuit that provides an error signal in response to the algebraic difference between a reference signal and the sum signal. The error signal is coupled to the light emitting diode for governing an intensity of the spot, thereby normalizing the position signal.

Abstract: A linear or rotary disk memory drive having provision for compensating or cancelling track position syncopation. Due to interference among the magnetic fields of magnetic dibits recorded in and adjacent to a servo code field in a magnetic memory disk, magnetic field intensities are displaced, producing an indication of a track center displaced from the actual track center. A magnetic head tracking such displaced magnetic fields is consequently displaced from track center, which is unacceptable. Four phases of magnetic dibits of servo code are recorded in each of at least four consecutive circumferential frames in a memory disk, in differing servo code formats or patterns of magnetic dibits.

Abstract: An improved system and process is provided in a disc drive for determining and for compensating head/track offsets when a data (target) head is moved to a new data (target) track position. Such disc drives typically include an armstack with transducer heads thereon, either pivotally or linearly mounted to move the transducer heads radially across a plurality of memory discs in a disc stack. A dedicated reference head is provided for scanning dedicated servo tracks on a dedicated memory disc, and a data head is provided on each data disc.Head/track position offset is determined by generating an initial position offset signal indicative of the position offset between the dedicated head and an adjacent dedicated track while a selected data head, called the present head, is centered on its data track.