Epson 3865X Plus User Manual page 78

All disks are divided into data storage compartments by sides,
tracks, and sectors. Double-sided diskettes store data on both
sides. On each side, there are concentric rings, called tracks, on
which a disk can store data.
A disk is further divided by sectors. To understand what a sector
is, picture the spokes on a bicycle wheel radiating from the hub
of the wheel to the tire. The space between one spoke and the
next is like a sector on a diskette. The figure below provides a
simple representation of tracks and sectors.
Double-sided, double-density diskettes have either 40 or 80
tracks on each side, and double-sided, high-density diskettes
have 80 tracks on each side. Diskettes can have 8,9,15, or 18
sectors per track.
Using Your Computer
3-11