fig. 1
A computer as shown in Fig. 1 performs basically five major operations
or functions irrespective of their size and make. These are 1) it accepts data
or instructions by way of input, 2) it stores data, 3) it can process data as
required by the user, 4) it gives results in the form of output, and 5) it
controls all operations inside a computer. We discuss below each of these
operations.
1. Input: This is the process
of entering data and programs in to the computer system. You should know that
computer is an electronic machine like any other machine which takes as inputs
raw data and performs some processing giving out processed data. Therefore, the
input unit takes data from us to the computer in an organized manner for
processing.
2. Storage: The process of saving
data and instructions permanently is known as storage. Data has to be fed into
the system before the actual processing starts. It is because the processing
speed of Central Processing Unit (CPU) is so fast that the data has to be
provided to CPU with the same speed. Therefore the data is first stored in the
storage unit for faster access and processing. This storage unit or the primary
storage of the computer system is designed to do the above functionality. It
provides space for storing data and instructions.
The storage unit performs the following major functions:
- All data and instructions
are stored here before and after processing.
- Intermediate results of
processing are also stored here.
3. Processing: The task of
performing operations like arithmetic and logical operations is called processing.
The Central Processing Unit (CPU) takes data and instructions from the storage
unit and makes all sorts of calculations based on the instructions given and
the type of data provided. It is then sent back to the storage unit.
4. Output: This is the process
of producing results from the data for getting useful information. Similarly
the output produced by the computer after processing must also be kept
somewhere inside the computer before being given to you in human readable form.
Again the output is also stored inside the computer for further processing.
5. Control: The manner how instructions
are executed and the above operations are performed. Controlling of all
operations like input, processing and output are performed by control unit. It
takes care of step by step processing of all operations in side the computer.
FUNCTIONAL UNITS
In order to carry out the operations mentioned in the previous section
the computer allocates the task between its various functional units. The
computer system is divided into three separate units for its operation. They
are 1) arithmetic logical unit, 2) control unit, and 3) central processing
unit.
1 Arithmetic Logical Unit (ALU)
After you enter data through the input device it is stored in the
primary storage unit. The actual processing of the data and instruction are
performed by Arithmetic Logical Unit. The major operations performed by the ALU
are addition, subtraction, multiplication, division, logic and comparison. Data
is transferred to ALU from storage unit when required. After processing the
output is returned back to storage unit for further processing or getting
stored.
2 Control Unit (CU)
The next component of computer is the Control Unit, which acts like the
supervisor seeing that things are done in proper fashion. The control unit
determines the sequence in which computer programs and instructions are
executed. Things like processing of programs stored in the main memory,
interpretation of the instructions and issuing of signals for other units of
the computer to execute them. It also acts as a switch board operator when
several users access the computer simultaneously. Thereby it coordinates the
activities of computer’s peripheral equipment as they perform the input and
output. Therefore it is the manager of all operations mentioned in the previous
section.
3 Central Processing Unit (CPU)
The ALU and the CU of a computer system are jointly known as the central
processing unit. You may call CPU as the brain of any computer system. It is
just like brain that takes all major decisions, makes all sorts of calculations
and directs different parts of the computer functions by activating and
controlling the operations.
Key
board
Key board is the main input device for our computer. It is fast accurate
device. The multiple character allow us to send data to our computer as a steam
of characters in a serial manner. It is efficient for jobs like data entry.
A full size key board has the distance between the centre of the key
caps is 0.75 inches. The key caps have a top of about 0.5 inches.
The key board layout is the array of the keys across the key board. The
most popular layout is QWERTY. Q,W,E,R,T,Y are the first six letters of the top
row of the alphabets of the QWERTY layout.
Monitor
Monitors are also known as Visual
Display Unit (VDU). A monitor is the television like box connected to our
computer. It shows what our computer is thinking. It has a display which is
technically defined as the image producing device that is the screen. They have
great sharpness and colour purity and operate at higher frequencies. They have
been classified on the basis of colour, signals and technology.
On the basis of colour monitors are classified into three types:-
1. Monochrome monitor
2. Gray colour monitor
3. Colour monitor
On the basis of signals monitors are classified into two types:-
1. Digital monitors
2. analog monitors
On the basis of technology monitors are classified into two types:-
1. Cathode Ray Tube (CRT) monitors
Mimetic technology monitors (LCD monitors) 
this is really helps to computer students. and mainly rural area students also.
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