What Are the Parts of a Hard Drive?

One of the key components of a computer system is the hard disk drive (HDD). It contains the operating system, programs and user-created files. While the operation of a hard disk drive is technologically complex, its physical makeup is relatively simple.

Magnetized Platters

Digital information is stored in an HDD on platters that resemble a CD-ROM disc. Both sides of the platter are finished with a magnetic coating that holds the information intact even after power is removed.

Read/Write Heads and Motor

The heads that read and write information to the platters are mounted on an actuator arm that is controlled by its own motor. The arm moves the heads on a linear track from the center of the platter to its edge.

Spindle and Motor

The spindle holds multiple platters at the spacing required to allow the heads to pass freely between them. The spindle motor rotates the platters at several thousand rpm, which causes the heads to "fly" on a micro-thin layer of air and allows for data access.

Electronics

The electronic controls for the HDD are contained on a printed circuit board attached to the underside of the drive case. One end of the case contains the power and data cable connections, and jumper pins for master, slave or cable select options.

Case

The case provides a solid base for the rotating parts and is sealed to prevent particles from contaminating the airflow between the heads and platters.

References

• Computer History Museum