A disk drive is a device used to retrieve and/or store data as part of a computer system's memory. The disk drive operates upon a disk, or platter, which holds the data. All disk drives are electromechanical in nature, meaning that they combine electrical circuitry with moving parts to perform the tasks of data storage and retrieval. Although there are different types of disk drives, they all share some common types of components, namely (1) an electric motor to rotate the disk; (2) a mechanism to store and retrieve data to and from the disk, usually called a read-write head. The read-write head can move from near the center of the disk out to its edge. By spinning the disk and moving the head from center to edge, the read-write head can access any area of the disk; (3) a disk controller, composed of digital circuitry, which performs...