Chapter 14. Hard Disk Drives
Replacing the original hard disk or adding a hard disk is one of the most common upgrades. It’s easy to do, and a very cost-effective way to extend the life of a PC. This chapter explains what you need to know to choose, install, and configure hard disks and interfaces.
How Hard Disks Work
All hard disks are constructed similarly.
one or more
, which are thin, flat, circular
objects made of metal or glass, substances chosen because they are
rigid and do not expand and contract much as the temperature changes.
Each platter has two
, and each surface is coated with a
magnetic medium. Most drives have multiple platters mounted
concentrically on the spindle, like layers of a cake. The central
spindle rotates at several thousand revolutions per minute, rotating
the platters in tandem with it.
A small gap separates each platter from its neighbors, which allows a
mounted on an
to fit between the platters. Each surface has its own read-write
head, and those heads “float” on
the cushion of air caused by the Bernoulli Effect that results from
the rapid rotation of the platter. When a disk is rotating, the heads
fly above the surfaces at a distance of only millionths of an inch.
head actuator assembly
resembles a comb with its teeth
inserted between the platters, and moves all of the heads in tandem
radially toward or away from the center of rotation.
Platters are cheaper than ...