Method and structure for locating and skipping over servo bursts on a

Abstract

A novel disk controller and method performed by a disk controller is disclosed which provides a highly efficient means of interrupting the reading or writing of a field in a sector on a magnetic disk, for skipping over a servo burst located anywhere within the field. The servo burst may be located at a different location in the fields of successive sectors. In the preferred embodiment, the servo burst skipping operation is controlled by microcode in the disk controller's sequencer RAM, and the servo burst skipping operation is initiated by a servo interrupt signal. The servo interrupt signal is generated by the disk controller when a servo burst is about to occur. This servo interrupt signal may be generated at fixed time intervals, using a count from a disk clock, or by counting the bytes in a sector leading to the servo burst. The number of bytes leading to the servo burst may vary, and, in one embodiment, the number of bytes before the servo burst occurs within a sector is contained in the ID field for that sector. The servo burst skipping operation performs the steps necessary for skipping over the servo burst and causing the microcode to return to an appropriate instruction in the microcode.