2.1.6 Output Devices

Output from a computer system may be used by the decision makers at all levels of an
organization. Output can take two basic forms. It can be either printed on paper or any
other permanent media. Also it can be displayed on a screen or output by other nonpermanent
means. This is called a softcopy such as on a floppy disk.

Sometimes the output from one computer can be an input to another computer. The form
of output might be visual, audio or digital.

Visual Display Unit (VDU)/Monitors

The display monitor is a TV-screen like device on which output from the computer is
displayed. A pixel is a dot of color on a photo image or a point of light on a display
screen. It can be in on or off mode. The quality of a screen is often measured by the
number of horizontal and vertical pixels used to create it. A monitor’s ability to display
color is a function of the quality of the monitor, the amount of RAM in the computer
system and the monitor’s graphics adapter card. The color graphics adapter (CGA) was
one of the first technologies to color images on the screen. Today it has changed to
super video graphics array (SVGA), providing vivid colors and superior resolution.

There are different types of VDUs. Based on the range of colors they can display two
types can be identified:
• Monochrome display screens
• Color display screens
Monochrome display screens can display only one color text on single color background,
i.e. white letters on blue, or green characters on black. In color screens various colors
can be displayed.

Another way of grouping them is based on their internal structure. The most common
type of monitor uses a cathode ray tube (CRT). Liquid Crystal Display (LCD) screens are
used in laptops. LCD monitors use the same technology which used for pocket
calculators and digital watches. This is a good solution especially if you do not have desk
space for a large CRT monitor or you need a portable computer. Plasma screens are
used for very large screens and in some modern laptops. They are flat screens with
good color, but are quite expensive. These screens are much easier on human eye
comparing to the CRT monitors. If you are using the monitor for long periods it is better
to purchase a high priced, low power consuming LCD panel, but if your usage is not
that frequent you could go for a low cost CRT monitor.

Printers

The job of a printer is to put on paper what you see on your monitor. How easy and how
successfully it is done depends on the choice of your printer. Selection of a printer is
based on many parameters such as cost, speed, type of paper used, quality or
resolution, size, type of cable connection etc. There are different types of printers. The
less expensive but a noisy version is a Dot matrix printer whereas expensive ones are
inkjet and laser printers. These are capable of producing high quality printouts and their
biggest advantage is that they are noiseless.

Plotters

A plotter consists of a device that can move paper both backwards and forwards. On the
top of the device one or more pens are able to move horizontally across the paper. The
combined movement of the pens horizontally across the paper and the vertical
movement of the paper allows complex continuous diagrams to be drawn. A plotter is a
specialized output device designed to produce high-quality graphics. Plotters are
especially useful for creating maps and architectural drawings, although they may also
produce less complicated charts and graphics.

Some plotters allow different colour pens to be used to create diagrams in multiple
colours.

In other types of plotters, the paper lies on a flat bed. The mechanics of the plotter are so
designed that the pens can move both across and down the paper to create the diagram.

Computer Output Microfilm Devices
Companies use computer output microfilm devices to place data from the computer
directly onto microfilm for future use.

Music Devices
MP3 is a standard format for compressing a sound sequence into a very small file while
preserving the original level of sound quality when it is played. Compressed sound file
requires less time to download the file and less storage space on a hard drive. MP3 is
facing competition from Windows Media from Microsoft, RealNetwork’s Real Audio and
an upgraded version of MP3 is called mp3PRO.