How Does a Disk Really Work?
A disk and a disk drive are somewhat like a record and a record player. The disk holds the files, just as a record holds the music. The disks, however, don’t have grooves. The disk has a smooth surface which is magnetized. When you format a disk, it’s divided into circular tracks, each of which is divided into ten sectors or so. This is just like the painted lines on a parking lot. The lines are magnetic lines. Of course, the size and numbers of the sectors can be adjusted to hold larger or smaller files. Take an old, used disk. Slide back the metal shutter and hold the disk at an angle to a bright light. You’ll see very small shiny concentric lines. These are the tracks. The disk drive has an arm, just like a record player’s arm. Instead of a needle, however, the tip of the head is a small electromagnet. When the drive is writing to the disk, the head magnetizes the disk surface in a sequence of positive or negative magnetic fields. Each field is a bit. For example, the letter B, whic
