Page 65 - Computer - 9(A&B)

OMR Sheet

Processing Device
Processing is the manipulation of data as per the given instructions. It is the logical
sequence of steps undertaken by a program to convert data into meaningful information.
The CPU (Central Processing Unit) is the processing device of a computer. It stores data,
intermediate results and instructions (program). It controls the operations of all parts of
the computer.

The CPU consists of three units:
 ALU or Arithmetic Logic Unit performs all the arithmetic and logical operations such as addition,
subtraction, division, multiplication, greater than, less than, etc.
 CU or Control Unit controls the activities of a computer system. It decodes instructions, determines the
storage area of instructions and data. It takes data to the ALU, and from the ALU to the main memory, and
then to any output device.
 MU or Memory Unit receives data, holds it, and delivers it according to the instructions from the Control
unit.
It is the Control Unit (CU) which is directing the data fl ow in IPO cycle to produce the desired result.

“CPU is called the brain of the computer.” Justify the statement.
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Output Devices

The output generated by the computer is stored digitally in the main memory of the system. Output devices are
used to produce these results in a user readable form. Mainly the user output is produced either in hard or soft
copy. Various types of devices like monitor, speakers, printer, plotter, etc are used to get the different types of
output.
Let us discuss the functioning of these devices one by one.

Monitor or VDU (Visual Display Unit)
This is the most commonly used output device which is used to display the user’s information in soft copy. It
looks like a TV screen on which images are formed with the help of thousands of picture elements present on the
screen called pixels. The quality of the output depends upon the number of pictures elements present per unit
area. Higher the number of pixels, better, will be the quality of output. The display can be color or monochrome
form.

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