COMPUTER AND ITS FUNCTIONAL COMPONENTS

WHAT IS COMPUTER ?

FULL FORM :- commonly operating machine particularly used for trade, education and research

Fig. Computer System

DEFINATION :- A  computer is an electronic device that can perform a variety of operations in accordance with a set of  instructions called program.

 Computer can access and process data millions of times faster than humans can. A computer can store data and information in its memory, process them and produce the desired results. Computers can do a lot of different tasks such as playing games, railway reservation, weather forecasting, error detection and controlling the flight of a space aircraft etc.

FUNCTIONING OF A COMPUTER

Before we start discussing the functioning of a computer, let us understand the way we function. To understand this, we will take some examples.

1.      Consider a case when your mother ask  you  to bring a cake and pastries from the market. You go to the market, purchase both the things and give it to your mother.

2.      You want to talk to one of your friends. His phone number is 123589654. So you dial up the number and speak to your friend.

In all, the examples certain thing(s) were needed to work upon, the actual work was then carried out accordingly and finally the result was obtained. In these examples undergoes three stages : the first stage (things to work upon) is called input stage ; the second ( the actual work being performed) is called process stage and the third stage ( the result) is called output stage.

FUNCTIONAL COMPONENTS OF A COMPUTER

Since a computer follows input-process-output cycle, the first stage is performed in computer by input unit, second stage is performed by its central processing unit and the third stage is performed by output unit. Thus the basic structure of a computer is as shown in fig.1

Fig.1 Basic Computer System

INPUT UNIT :-

The input unit is formed by the input devices attached to the computer. Examples of input devices and media are keyboard, mouse, magnetic ink character reader (MICR), optical mark reader (OCR), joystick etc.

The input unit is responsible for takinginput and converting it into computer understandable form ( binary code). Since a computer operates on electricity, itcan under stand only the language of electricity i.e. either ON or OFF or high voltage or low voltage.

CENTRAL PROCESSING UNIT :-

It is the control centre for a computer. It guides, direct and governs its performance. It is the brain of the computer. The CPU has two components which are responsible for different functions. These two components are control unit and Arithemetic Logic Unit.

ARITHMETIC LOGIC UNIT ( ALU ) :-

The ALU performs all the four arithmetical ( +, -,*,/ ) and some logical ( <,>,=, >=, <> ) operations. When two numbers  are required to be added , these numbers are sent from memory to ALU where addition take place and the result is put back in the memory .In the same way , other arithmetic operations are performed ( through ALU only ).

       For logical operations also, the numbers to be compared are sent from memory to ALU where the comparison take place  and the result is returned to the memory. The result of a logical operations is either TRUE or FALSE .These operations provide the capability of decision –making to the computer.

CONTROL UNIT:-

The control unit controls and guides the +interpretation, flow and manipulation of all data and information. The CU sends control signals until the required operation are done properly by ALU and memory. Another important function of CU is the program execution. The CU gets program instructions from memory and executes them one after the other. After getting the instructions from memory in CU, the instruction is decoded and interpreted.

  The control unit even controls the flow of data from input devices to memory and from memory to output devices

OUTPUT UNIT:-

 The output unit is formed by the output devices attached to the computer . The output coming from the CPU is in the form of electronic binary signals which needs conversion in some form which can be easily understood by human beings i.e. characters, graphicalor audio visual . This function of conversion is performed by output units. Some popular output devices are VDU ( Visual Display Unit ), printer, plotter, speech, synthesizer and coder etc.

THE MEMORY:-

If a computer has a brain ( CPU ), it must also have the faculty which we call memory .

The memory of the computer is more like a predefined working place, where it temporarily keeps information and data to facilitate its performance. When the task is performed, it clears its memory and memory space is then available for the next task to be performed. When the power is switched off, everything stored in the memory gets erased and cannot be recalled.