Examples of Input Devices

Input Devices

                   

Input devices are used ti input the data into the computer, processing.The data input to a computer can be in the form to text,audio,video,etc.The various input devices are given below:

• Keyboard
• punch card
• mouse
• trackball
• joystick 
• digitizers/digitizing tablet
• light pen
• touch screen
• touchpad
• Speech recoginition 
• Digital camera

Keyboard 

this is the standard input device attached to all computers.The layout of keyboard is just like the traditional typewriter of the type QWERTY.It also contains some extra command keys and function keys.It contains to a total of 101 to 104 keys.you have to press correct combination of keys to input data. The computer can recognize the electrical signals corresponding to the correct key combination and processing is done accordingly.

The keys of the keyboard are divides as:

1.Alphanumeric key:The alphanumeric keys are arranged the same way on almost every keyboard and look like a typewriter keys.

2.Numeric Keypad:Numeric keypad is usually located on right side of the keyboard,look like and adding machine,with its ten digits and mathematical operators(+-*/).

3.Function keys:This part of the keyboard consists of the function key(F1,F2........F10) arranged in arow along the top of the keyboard.Each function key's purpose depends on the program you are using.

4.Cursor Movement keys:Cursor movement keys allow you to move around the screen.Most keyboards have the keys such are arrow keys to move the cursor up/down single line or left/right one character space, home/end key,page up/page down key.

5.Special Purpose key:These keys perform a specialized functions.The special purpose keys are insert,delete,esc,print screen,scroll lock,pause etc.

6.Modifier Keys:These keys are used to modify the input or other keys.You press another key-whole holding down one on of the modifier key.The various modifier keys are shift,ctrl,alt.

Punch card 

Punch cards were actually invented before electronic computers. originally patented by Herman Hollerith,the punch card was first used with tabulating machines to record vital statistics.

  Punch card(or punched card ),a recording ,medium in the form of a card made of paper,paperboard,or,more rarely,plastic and of a standard shape and size;data are recorded on the card by punching holes.Punch cards are used primarily for the input and output of data in computer and as the basic recording medium in punch card processing equipment.They exists in many types,which differ in shape,size,volume, of information stored,and the shape and arrangement of the holes.Most of the punch cards used have 80 columns-45 columns are encountered in obsolete computer units-and are made of heavy paper stock 0.18 mm thick in the shape of a rectangle with sides of 187.4 and  82.5 mm.The top left corner of the card is cut off for convenience in sorting and stacking.The columns are marked off across the card from left to right.The card is also divided into 12 rows-10 primary and 2 supplementary.Up to 80 characters-approximately 10-15 words-can be recorded on one punch card.The processing rate for machine punch cards can reach 2000 cards/min.Data are ready by means of electromechanical readers or photoelectric cells.Punch card with 90,40,and 21 columns and 6,12,10 rows,respectively are also used.Special forms of punch cards and 21 columns and 6,12 and 10 rows,respectively are also used.Special forms of punch cards are edge-punched cards,which are used in information systems,and cards for automatic typewriters.

input devices
input devices of computer