input devices

igcse info on input devices.

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  • Created on: 10-08-12 18:08
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An input device is something you put in a computer.
E.g.
QWERTY keyboard: when you press a key, a number code is sent to the computer to tell it what key
you pressed.
Concept keyboard: a flat board that has a grid of switches. Each switch is programmed to do what
you want. It can be used in tills at restaurants; it has all the meals that can be bought. The waiter
presses the right meal name when a meal is bought.
Scanner: can be used to put printed images or photos into the computer .It shines a light on the
image and measuring how much light reflects back using an optical sensor. They read the information
one line at a time.
Mouse: is used as a pointer that points things. You move it around on the mat and the pointer on the
screen follows your movements.
Joystick: used for playing games. You can move it in one of eight directions and it tells the computer
what direction is being pulled and it uses that info to move your character on the screen. The best
ones can tell how far in that direction it is being pulled.
Light pen: used to draw on the screen, but they can be inaccurate and hard to use, and were more
popular in the 1980's and the 1990's.
Graphics tablet: is a flat pad where you can draw using the stylus. As you draw on the pad, the
picture appears on the screen. It can produce a much more accurate picture than when using a mouse.
Digital camera: Digital cameras do not use film, inside one are light sensors. When a picture is taken
the array of light sensors are used to input the image. The pictures can then be transferred onto a
computer.
Touch screen: It can be used for the information system in tourist's office window, where a mouse
can get very wet or dirty, but it can be tiring to keep touching the screen.
Tracker ball: Works as the same way a mouse does, except the ball is on the top. By turning the ball
with your hand you can move the pointer on the screen, and it doesn't need as much space as a
mouse either.
Video digester: Takes an image from a TV or a video camera and converts it so it can be stored in a
computer. It can capture moving images.
Voice recognition: They listen to what people say and carry out their instructions. Some can only
understand a few words spoken by each person, while others can recognise a wide vocabulary but
need to be trained to recognise each voice.

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Direct Data Entry Devices (DDE):
Inputting large amounts of stuff directly into the computer.
Bar codes: made of a lot of bars different sizes which represent different numbers. They are read
into a computer using a fixed scanner.
Magnetic strips: can store 60 characters of info stored magnetically. They are normally on credit
cards, and have to be swiped through a machine to read the pattern of magnetism.
Smart Card: looks like a magnetic stripe card but it contains a small RAM chip.…read more

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