If You Want to Know More
How Does a Disk Store Information?
Part I: Getting To Know Your Computer
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How Does a Disk Store Information?
The answer depends on the type of disk.
Hard Disk and Diskettes
Hard disk and diskette drives work in the same way, although the
hard disk has much higher capacity and provides much faster data
access than a diskette.
Like a tape recorder, a disk drive reads and writes magnetically
encoded information on magnetic media. The drive positions a
read/write head above the surface of the disk when it records and
retrieves information.
Before a drive can read from or write to a disk, the disk must have
a specific structure. Formatting a disk creates this structure.
Tracks and sectors of a disk
Formatting divides each side of the disk into concentric circles
called tracks. Each track is divided into sectors. Each item of infor-
mation stored on a disk has a specific address composed of its
side, track and sector number. This address makes it possible for
the computer to locate the information on the disk.
A diskette has just two surfaces. A hard disk consists of a set of
platters on a central spindle. So it has several surfaces, with a read/
write head for each.
Tracks
Sectors (within one track)
Item of information
000-book.bk : 14-nerd.fm5 Page 316 Wednesday, May 15, 1996 4:15 PM