There
are several devices used for inputting information into the computer: a
keyboard, some coordinate input devices, such as manipulators (a mouse, a
track ball), touch panels and graphical plotting tables, scanners, digital
cameras, TV tuners, sound cards etc.
When personal computers first became popular, the most
common device used to transfer information from the user to the computer
was the keyboard. It enables inputting numerical and text
data. A standard keyboard has 104 keys and three more ones informing about
the operating mode of light indicators in the upper right corner.
Later when the more advanced graphics became to
develop, user found that a keyboard did not provide the design capabilities
of graphics and text representation on the display. There appeared
manipulators, a mouse and a track ball, that are usually used while
operating with graphical interface. Each software program uses these buttons
differently.
The mouse is an optic-mechanical input device. The mouse has three or two buttons
which control the cursor movement across the screen. The mouse provides the
cursor control thus simplifying user’s orientation on the display. The
mouse’s primary functions are to help the user draw, point and select images
on his computer display by moving the mouse across the screen.
In general software programs require to press one or
more buttons, sometimes keeping them depressed or double-click them to issue
changes in commands and to draw or to erase emages. When you move the mouse
across a flat surface, the ball located on the bottom side of the mouse
turns two rollers. One is tracking the mouse’s vertical movements, the other
is tracking horizontal movements. The rotating ball glides easily, giving
the user good control over the textual and graphical images.
In portable computers touch
panels or touch pads are used instead of manipulators. Moving a
finger along the surface of the touch pad is transformed into the cursor
movement across the screen.
Graphical plotting tables (plotters) find application in drawing and inputtig manuscript
texts. You can draw, add notes and signs to electronic documents by means of
a special pen. The quality of graphical plotting tables is characterized by
permitting capacity, that is the number of lines per inch, and their
capability to respond to the force of pen pressing .
Scanner is used for optical inputting of images (photographies, pictures, slides)
and texts and converting them into the computer form.
Digital videocameras have been spread recently. They enable getting videoimages and photographs
directly in digital computer format. Digital cameras give possibility to get
high quality photos.
Sound cards produce sound conversion from analog to digital form. They are able to
synthesize sounds. Special game-ports and joysticks are widely used in
computer games. |