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Light Pen
A light pen is a pointing device shaped like a pen and is connected to a VDU. The tip of the light pen
contains a light-sensitive element which, when placed against the screen, detects the light from the
screen enabling the computer to identify the location of the pen on the screen. We generally use it to
Light Pen make a selection or draw anything on a screen.
Touchscreen
Touchscreen is the latest in the input devices where the input can be taken from the
user through a touch of a finger, stylus or a light pen on a display screen. We can
give the entire set of commands by touching. Nowadays most of the laptops, Smart
TV, smartphones, tablets, etc. also have touch screens where the use of the keyboard
is minimised. It is a very useful and convenient alternative to a mouse or a keyboard
in a graphical user interface. Touchscreen
Microphone
Microphone is a device that converts the sound received into a digital audio form which can be
easily stored or manipulated in a computer.
Microphone
Barcode Reader
A bar code is a set of parallel lines that appear on the products as their identification.
You will find most of the packages having these barcodes that can be easily read by
barcode readers. Bar code readers work by placing a beam of light on the lines that
make up the bar code and detecting the amount of light that is reflected back. The
barcode read is then stored in the computer for preparing invoices. Barcode Reader
MICR
The bank account number and other details are printed onto bank cheques which are
read by Magnetic Ink Character Recognition using a special magnetic ink. They are useful
to find out whether the cheque is genuine or fake.
MICR
PROCESSING DEVICE CENTRAL PROCESSING UNIT (CPU)
After taking the input from the input devices, the information is sent for processing. The computer uses its brain to
process the information. The computer’s brain is called the CPU or Central Processing Unit. CPU is basically divided into
three parts:
• ALU stands for Arithmetic Logic Unit. It is responsible for all arithmetical and logical
calculations.
• CU stands for Control Unit. It controls the flow of information in the system. The control
unit is responsible for the flow of data from input devices to the processing unit and then
to the output devices. It works like a traffic policeman who controls the traffic on the road.
• MU stands for Memory Unit. It is a storage unit that holds the processed or unprocessed
CPU Chip data.
60 Trackpad Information Technology-IX

