CS 121 Lecture Notes - Lecture 37: Stepper Motor, Hard Disk Drive, Removable Media
28 Jul 2020
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Lecture 37: with each access to information, the hard disk performs a wide range of tasks. Below are the fundamental steps involved in each disk access: first, several translation stages are performed, which make a direction (a number pointing to a disk position) translate into a geometric location, of type (cylinder, head, sector). Then, the disk is rotated, if it was not already running. When the disk reaches a stable speed, the heads are moved to the desired cylinder, using the stepper motor that controls the arms. Once in the appropriate cylinder, the head corresponding to the desired plate is activated. Then, wait the time needed for the disc to turn to the desired sector under the head. When this happens, the information is read or written in that sector: as we have already mentioned, this process only includes the basic steps. In fact, the process involves several additional steps.
