Epson 20 - Manual (Page 66)

A hard disk consists of two or more platters stacked on top of one
another; so it has four or more sides with many more tracks per side
than a diskette. (The number of tracks depends on the capacity of the
hard disk. You do not need to know how many sides and tracks your
hard disk has.)
A disk is further divided by sectors. To understand what a sector is,
picture the spokes on a bicycle wheel radiating from the center of the
wheel to the tire. The space between one spoke and the next is like a
sector on a diskette; the lines dividing the sectors cut across the
tracks. (See the figure below.) A diskette can have 8, 9, 15, or 18
sectors per track. The number of sectors on a hard disk depends on
the type of hard disk.
track
Your computer uses the read/write heads in a disk drive to store and
retrieve data on a disk. To write to a disk, the computer spins it in the
drive to position the area on the disk where the data is to be written
under the read/write head. A diskette has an exposed area where the
read/write head can access it.
Using
the Equity 386 4-9