Basic components of hard disk

A hard disk is comprised of four basic parts: platters, a spindle, read/write heads, and integrated electronics.

Platters are rigid disks made of metal or plastic. Both sides of each platter are
covered with a thin layer of iron oxide or other magnetizable material.
• The platters are mounted on a central axle or spindle, which rotates all the platters at
the same speed.
• Read/write heads are mounted on arms that extend over both top and bottom
surfaces of each disk. There is at least one read/write head for each side of each
platter. The arms jointly move back and forth between the platters’ centers and
outside edges; this movement, along with the platters’ rotation, allow the read/write
heads to access all areas of the platters.
• The integrated electronics translate commands from the computer and move the
read/write heads to specific areas of the platters, thus reading and/or writing the
needed data.