Abstract: According to one embodiment, a disk drive includes a medium scanner and a threshold manager. The medium scanner measures the write count of each head with respect to a disk. The medium scanner executes a read verify process by which data is read out from the disk, during idle state, when the write count is equal to or larger than a predetermined threshold value. The medium scanner rewrites the recovered data to the disk, if a read error occurs and the error is recoverable. The threshold manager initially sets the write count threshold value of each head in accordance with the head performance, and dynamically changes the write count threshold value in accordance with the error rate when the device is in operation.

Abstract: A programming system for preparing stitch instructions for the purpose of controlling the relative position between a needle and a workpiece by means of so varying the relative position between an index member and a record medium as the index member traces after the profile figured on the record medium. In this system a manual operating member is disposed for designating the direction and speed of variation of the relative position between the index member and the record medium. An exact tracing of a profile of complicated shape is made possible by designating the speed appropriate for the tracing of the profile through varying the angle of inclination of the manual member according to the shape of the profile. The programming operation for preparing the stitch instructions can be performed in this way exactly and easily.