Author Topic: IN-PUT DEVICES of COMPUTER  (Read 638 times)

Offline Md. Al-Amin

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« on: April 02, 2014, 02:53:59 PM »

Which components are used to give information or data or instructions to the computer are called as In-put devices.


1. KEY BOARD (Standard): Keyboard is one of the most common input devices for computers. The layout of the keyboard is like that of the traditional QWERTY type writer, although there are some extra command, function keys provided for substantial development has taken place in the ergonomics of keyboard design to ensure that operator strain is minimal. Keyboard usually contain the following keys.

a. FUNCTION KEYS : Which are preprogrammed for specific operations. These can also be programmed by the user so as to work in a way he desires. These are labeled from F1 to F12. These are placed in the upper side of keyboard sequentially.

b. TYPE WRITER KEYS : These keys are in the form of standard QWERTY layout of the type writer.

c. SPECIAL KEYS: Esc, Ctrl, Alt, Enter/Return, Print Screen, Insert, Del, Scroll Lock, Pause Break, Caps Lock, Nums Lock, Shift.

d. CURSOR CONTROL KEYS : Which are usually used for cursor controls. Left arrow, R-arrow, U-arrow, D-arrow, PgUp, PgDn, Home & End.

e. NUMERIC KEY PAD : Which are arranged as a pad as same as calculator, which are used for inputting numeric values. These are placed in the right most corner in the keyboard.

2. MOUSE : This In-put device is used specially for graphical user interface (G U I). Which can be moved on a smooth surface to simulate the moment of cursor that is desired on the display screen. It contains one to three buttons. One can point to any place on screen, make selections click an option etc. So that input is provided to the computer. This is used as a pointing device. This is also called as MICE.

3. MICR (Magnetic Ink Character Reader/Recognizer) : This MICR reader reads the characters, which are written using special magnetic ink. These are also human readable. This way of input using magnetic ink is used in banking where cheque numbers, account numbers and banks identification number are printed using special magnetic ink. The major limitation of MICR is that it can recognize. Only 10 digits and special character, you can not use alphabetic characters.

4. OCR (Optical Character Reader/Recognizer) : This is the most sophisticated optional recognition, which recognizes specially shaped numeric and alphabetic characters. It directly reads any printed character and no special ink is required. OCR can read at a speed of about 2,400 characters per second.

5. BCR (Bar Code Reader/Recognizer): Bar code is a special code, which is forming with vertical lines. This code contains cost of the item, date of manufacturing, batch number and manufacturer information. The bar code reader is used to decoding the above information.

6. MODEM (Modulator De-modulator) : It is used for communication of information between two or more computers. It can convert digital signals into analog signals. This process is called as modulation and convert analog signal into digital. This is called as De-modulation.