Abstract: A method is disclosed for determining fundamental-frequency repeatable runout (1FRRO) coefficients in a disk drive. The disk drive includes a transducer head, a rotating magnetic disk having a plurality of concentric data tracks defined by embedded servo wedges that provide position information, and an actuator coupled to the head. In the method, the head is caused to move in a substantially constant velocity motion across a selected portion of the tracks of the rotating magnetic disk in response to a control signal. The position information is read from the embedded servo wedges as the head moves across of the selected portion of the tracks. The 1FRRO coefficients are determined based on the position information read as the head moved in a substantially constant velocity motion across the selected portion of the tracks.

Abstract: Disclosed is a control system for processing sampled servo data in a disk drive. The control system includes a microprocessor and a servo processing accelerator circuit for performing operations on the sampled servo data while the microprocessor is executing firmware code. The accelerator circuit supports the use of a higher servo bandwidth thus allowing a higher track density resulting a greater storage capacity for the disk drive. Also, the accelerator circuit relieves the microprocessor of the ordinary servo processing function. Thus, the microprocessor's limited processing capacity to be directed to other controller and interface functions of the disk drive. Only under unusual conditions, such as a write-unsafe (WUS) limit exception, does the microprocessor need to direct processing capacity to the servo processing function. Further, the accelerator circuit may be a decreased response time after reading the servo data from the disk.

Abstract: The present invention is directed to a disk drive which can assert control over the information content supplied in response to a read request from the host by performing a selective translation of addresses received from the host. The disk drive can include hardware, firmware, or a combination thereof, to unambiguously detect a command block to read a predetermined location on the drive. The drive, upon detecting occurrence of a predetermined address included in the command block, translates the address to initiate a read from an alternate, substitute location information stored at the substitute location is returned to the requesting host in satisfaction of the host's request. The information can be blocks of data, such as audio/video data, or can be executable code including, but not limited to, code used to boot a substitute operating system stored at a location known only to the drive.