Input and Output Devices

INPUT DEVICES

A device that can be used to insert data into a computer or other computational device. Ex - Keyboard, Microphone etc. An input unit takes the input & converts it into binary form so that it can be understood by the computer.            Input devices are various types it can be shown in below: KEYBOARD                 This is most commonly used device which acts as input device. Its structure is like typewriter.It contains no. of  keys which have some specific ASCII values. Like ‘A’ has ASCII value 65. When this is pressed , it is converted into 65 & this 65 is sent to CPU in the form of Binary language (i.e. 1000001). Then operations are done on this data. MOUSE                This is a pointing device which contains a roller in its base. When the mouse is moved on any surface, the pointer on the screen is also moved. It contains a potentiometer coupled with the roller. This potentiometer senses the motion of mouse & convert it into digital value. A mouse may contain two or three buttons.  BAR CODE READER It is a device which is used to read the code from the products which are usually in the form of Bars. It contains a light sensitive detector which identifies the values of the bars on the product & converts them into numeric code.These Bar readers are used in Shopping malls in a very large scale. DIGITAL CAMERA As the name specifies, these camera stores the data digitally, which then can be stored in the computer & can be stored for a long time. But it has very limited storage capacity. These are very popular because of less expensive photographs & Speed. LIGHT PEN It is a pointing device which contains a photocell mounted at its tip. It senses the light from the screen when it becomes closer to the screen, & generates a pulse. So for identifying a particular location on the screen these light pens are very useful. But this is not in very much use these days.

SCANNER

The scanner is an input device like the photocopier machine which makes the electronic copy of the picture or document which can be further edited.

MIC's or MICROPHONES

The scanner is an input device like the photocopier machine which makes the electronic copy of the picture or document which can be further edited.

OUTPUT DEVICES

             The devices which are used to display the data to the user either in the form of hard copy or soft copy are called output devices.

Output devices are various types it can be shown in below:

SPEAKERS

Speakers receive the sound in the form of electric current from the sound card & convert it to sound format. These are used for listening music, chatting , seminars for presentations etc.

VDU (Visual Display Unit)

This is also called monitor. It is used to get the data in the form of soft copy. Their functioning is exactly similar to the television. It contains a CRT which emits the electrons to trace a regular pattern of horizontal lines on the screen.

PRINTER

These devices gives the hard copy of the output. These are in different types.

Impact - Have mechanical contact in between paper & printing head

Non Impact - No mechanical contact between paper & printing head

IMPACT :

Line Printers - print line wise (E.g. Drum Printer)

Character Printer - print character wise (E.g. Daisy Printer)

NON IMPACT -

Electromagnet Printers

Thermal Printers

Electrostatic Printers

Inkjet Printers

Laser Printers

LCD (Liquid Crystal Display)

These screens are used in laptops & notebook sized PCs. A special type of liquid is sandwiched between two plates. The top plate is clear & bottom plate is reflective. The molecules in these liquids are normally aligned & the computer signals are used to align these molecules.