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ground: A conductor to which all components of an electric circuit are
connected. It is connected to the earth and is the point of reference
for voltages in the circuit.
GUI (Graphical User Interface): A user interface that uses a mouse and
a bit-mapped graphics display to make basic computer operations
substantially easier for the user. Standard features include message
boxes, a clipboard, dialog boxes, scroll boxes, WYSIWYG (what-
you-see-is-what-you-get) on-screen page presentation, and multiple
on-screen windows.
H
half duplex: A type of data transmission in which data flows between
two devices in one direction at a time. See also full duplex.
handles: Eight small boxes that appear around a graphical object when
you select it. You can use the handles to change the size and shape
of the object. Dragging the middle handle on one side of an object
stretches or shrinks the object in that direction, changing its shape as
well as its size. Dragging a corner handle makes the object larger or
smaller while preserving its shape.
hard disk: A storage device composed of a rigid platter or platters that
store information magnetically. Hard disks hold much more
information than diskettes and are used for the long-term storage of
programs and data. The primary (or only) hard disk in a personal
computer is usually fixed, but some computers have secondary hard
disks that are removable. In a server, all hard disks may be
removable. By default, the primary hard disk is referred to as drive
C.
hardware: The physical, electronic, and mechanical components of a
computer system, including devices such as a screen, disk drive,
printer, mouse, and processor.
hexadecimal: The base-16 numbering system used by programmers to
represent binary numbers. Digits above 9 are represented by letters
(the 15 digits are 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F). Two
hexadecimal digits are equivalent to the eight bits in a byte. For
example, F1 in hexadecimal is equivalent to 11110001 in binary.
See also binary, decimal.
high-density diskette: A diskette that holds 1.2 MB (5.25-inch) or 1.44
MB (3.5-inch) of information.
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Glossary
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