Computer is an electromechanical device. Which accept the data, instruction evaluate them and finally provide the result according to relevant target. The entire procedure of computer working is depending on IPO (input process output) cycle.

Characteristics: speed, accuracy, storage, deligency (repetition of job), etc.

Input and output device:

Input device:-

input devices read information prepared by human and translate the human languages into machine and vice versa. A computer system may have one or more of the following input devices depending upon its use.

1. Keyboard
2. Mouse
3. Scanner
4. Light Pen
5. MIC
6. OCR  etc...

key bord: The keybord is one of the most input device for computer.by which raw material and instruction are sent to comuter system .The layout of the keybord is like that of the traditional typewriter keybord,An ordinary keybord  contain 101 keys. Entire lays of keybord is divided in to 6 phages.

1. Numeric key(0-9)
2. alfabatical key(a-z,A-Z)
3. Functional key(f1-f12)
4. special key( spacebar, tab, shift,Alt,Ctrl ,enter, Page up, page dn del, backspace, etc)
5. arrow key
6. multimedia key (power, play, stop, mail, mycomputer etc)

Mouse: The mouse is a handy device which can be moved on a smooth surface. The object on the screen can be selected by playing the arrow shaped cursor on the object and clicking the mouse button. The muse could be optical offering realiable operation,or mechanical which is cheaper but noiser.the advantage of mouse is that we donot have to physically type the characters available on the keyboard

Scanner: It is an input device which send the image into computer stystem through absorbing property basically picture cartoon complicated graphics are input through this device

Light pen: It is a pointing input device which is similar to a dot pen into physically construction with this device drawing and artistic work can be done

Output device

The device  which  is used to translate the computers output into its human readable form either in the form of a hard copy or in visual way.
The following output device are :

1. VDU.
2. Printer
3. Plotter
4. Speaker
5. Modem

VDU:- IT’S  full from is visual display unit. It is often in the form of  T.V. it consist aC.R.T which produse the beam of electron that make picture on the screen. It do not receved t.v signal. It is also called moniter or screen.
There are three type of VDU :

1. MONOCHROME MONITER
2. VGA or RBG (Vidio graphic array)
3. SVGA (Super video graphic arry)

Printer: It is a complet output device which provide the hard copy output in form of permanent.

Plotter: I is very power full and expencive output device because it contain the latest technology hardware resorce . it provide real and natural image of the thing.

Ploter: It is very powerfule and expencive output device because it contain the latest technology.
            
Speaker: It is output device. They produse sound.

Modem: A device that allows a computer to transmit data over telephone lines. It is the most common way that people connect to the Internet. A modem modulates data by converting it to audible tones that can be transmitted over a telephone line, and then demodulates received signals to get the data.