How Computers Work, Ninth Edition

Chapter 11. How Disk Drives Save Information

IN more ways than one, a computer’s disk drives are where the action is. The platters on which data is stored spin at speeds of up to 15,000 revolutions a minute—167 spins each second. Each time the hard drive is accessed to read or save a file, it causes the read/write heads to burst into a flurry of movement that must be performed with microscopic precision. So exacting are the tolerances in a hard drive—the gaps between the heads and the platters aren’t big enough to admit a human hair—it’s a wonder the drive can perform its work at all without constant disasters. Instead, it keeps on plugging away ...