<hardware, storage> (Or "hard disk drive", "hard drive", "floppy
disk drive", "floppy drive") A peripheral device that reads and
writes hard disks or floppy disks. The drive contains a motor to
rotate the disk at a constant rate and one or more read/write
heads which are positioned over the desired track by a servo
mechanism. It also contains the electronics to amplify the
signals from the heads to normal digital logic levels and vice
versa. In order for a disk drive to start to read or write a
given location a read/write head must be positioned radially
over the right track and rotationally over the start of the
right sector. Radial motion is known as "seeking" and it is this
which causes most of the intermittent noise heard during disk
activity. There is usually one head for each disk surface and
all heads move together. The set of locations which are
accessible with the heads in a given radial position are known
as a "cylinder". The "seek time" is the time taken to seek to a
different cylinder. The disk is