A disk drive comprises a disk, an actuator arm and a servo controller using a position error signal to generate a controller output signal to control the actuator arm. The barcode reading station includes a holster for a barcode reader, the barcode reader producing a scan volume, a barcode reading table for identifying a target location for barcode reading, and a mirror for deflecting the scan volume of the barcode reader towards the barcode reading table. By such arrangements, when the user puts on the shoe, the present invention can rectify the positions of the toes and can massage the toes by the bioelectricity discharged by the biochemical balls. An ending value associated with an end of the preamble portion is determined based at least in part on the first intermediate value and the second intermediate value.