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Unformatted text preview: a voice response system are soft-copy output.
2. Hard-copy output. A hard-copy output is an output, which is produced on a paper or
some material that can be touched and carried for being shown to others. They are
permanent in nature and can be kept in paper files or can be looked at a later time when
the person is not using the computer. For example, output produced by printers or plotters
on paper are hard-copy output.
Monitors are by far the most popular output devices used today for producing soft-copy
output. They display the generated output on a television like screen (see Figure 9.19). A
monitor is usually associated with a keyboard and together they form a video display
terminal (VDT). A VDT (often referred to as just terminal) is the most popular
input/output (I/O) device used with today's computers: That is, it serves as both an input
and an output device. The keyboard is used for input tu the computer and the monitor is
used to display the output from the computer. The name "terminal" comes from the fact
that a terminal is at the terminal, or end, point of a communication path.
The two basic types of monitors used today are cathode-ray-tube (CRT) and flat-panel.
The CRT monitors look much like a television and are used with non-portable computer systems. On the other hand, the flat-panel monitors are thinner and lighter and are
commonly used with portable computer systems like notebook computers.
How a CRT Monitor Displays an Output?
A CRT monitor is a glass tube with a screen at one end and an electron gun at the other
end. Its major components are shown in Figure 9.20. The electron beam generator has an
oxide-coated metal called cathode and a heating filament. The cathode emits a large
number of electrons when heated by the filament. In front of the electron beam generator
is a control grid that is applied with an appropriate positive voltage to allow the exact
number of electrons, out of the generated ones, to pass through it for striking at the
monitor's screen. Larger is the positive v...
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This document was uploaded on 04/07/2014.
- Spring '14