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What is Computer ? कम्प्यूटर क्या है?





WHAT IS A COMPUTER? 
    Computer is a device which accepts input, processes it, stores the data, if required and gives desired output as per user requirement. The term computer is used to describe a device made up of a  combination of electronic and electromechanical (part electronic and part mechanical) components. By itself, a computer has no intelligence and is referred to as hardware. In general the computer does the  following. 
1. Accept user supplied data and instructions. 
2. Stores large volume of information given at high speed as per the instruction given. 
3. Process the information given at a high speed as per the instruction given. 
4. Output the results according to user specifications
5. Transfers Data, Images, Sound and Graphics through cables at a very fast rate 

    In other words, we supply to the computer; the data to be processed and the instructions to 
process the data with. The computer remembers both the data and the instructions, does the processing 
when asked to, and give us the result in the specified format. 


Fig. shows the functional block diagram of a typical computer system.

Input Device 
    The function of the input device is to feed the necessary data and the instruction to the computer in computer understandable language. With the help of input device a user can communicate with  computers. Examples are keyboard, mouse, joystick, OCR, touch screen monitors etc. 

Output Device 
The function of output device is to translate the computer’s output into a language understandable by human beings. These devices are similar in operation to input device but perform opposite function. The examples are: Printers, monitor, plotters etc. 

Arithmetic and logic unit (ALU) 
It is one of the parts of central processing unit (CPU). As its name indicates it perform all arithmetic operation such as addition, subtraction, multiplication and it also takes logic decisions based on certain digital gates. Data is to be processed is taken from main memory and loaded into the accumulator in the ALU. After execution of data the result is sent to main memory under the direction of  control unit. 

Control unit 
It is also part of CPU and is clock of the computer. Its function is to fetch the instructions one by one in proper sequence and ensure that these instructions are properly executed by other units. It controls and co-ordinates all hardware. 

Main memory 
    Main memory is used to store information, which can be accessed when required. It is fast memory and data stored on it can be immediately retrieved from it. The main memory of computer is generally RAM, which is volatile semiconductor memory and stores the data awaiting processing and also processed data for short duration. 

Auxiliary/ secondary memory 
    As compared to main memory it has much larger capacity but not as fast as main memory .They are used to store the data and software of the computer permanently. Hard disk is the most commonly used secondary memory which stores the operating system, applications and the user’s data .The other examples are floppy disk CD and DVD etc. 

CHARACTERISTICS OF A COMPUTER 
    The four factors that lead a person to use a computer are Speed, Accuracy, Reliability, & Storage. 
In a nutshell, computers are fast, accurate, and reliable, they do not forget anything; and they do not 
complain. 

     Speed: One of the major advantages of the Computer is its Speed. It is determined by the number of instructions it can carry per second for the various process involved in a computer. It is measured in milliseconds, or thousands of a second. The speed of a computer is closely related to the amount of data it must process. To classify the speeds of different computer systems, the industry has developed the criterion of Million Instructions per Second (MIPS). 

     Accuracy: Computers cannot make mistakes. Errors do occur in computer-based information 
systems, but these errors are human errors. The probability of computer error is quite small and often traceable to faulty data. Computers rarely make mistakes and can accurately perform all kinds of complex computations.

     Reliability: Computer systems are widely accepted because of their exceptional reliability. Unlike most humans, they are capable of operating under the most adverse conditions for extended periods of time without showing any signs of fatigue. They do not take sick days and coffee breaks, and they seldom complain. Anything below 99.9 percent uptimes is usually unacceptable. Computers consistently provide the same accurate results under all operating conditions. Of course, computers do break down the require seneed regular maintenance checks to ensure that they are operating at peak performance level. 

     Storage: Computer systems have total and instant recall of data and an almost unlimited capacity to store these data. A typical computer system and perhaps thousands of graphic images, stored and available for instant recall. When properly used, a computer can improve the efficiency of an organization. It provides a fast, accurate, and reliable device with which data can be processed. 

HARDWARE 
    It is a general term which describes all the physical components used in the construction of a computer itself. It covers all tangible items of a computer that can be seen and touched.

Hardware Components 
    Fundamentally, a computer is a lot like the human body. The human body contains a brain, organs to help the body functions properly, and skin to protect the internal organs. All of the various parts of your body’s internal structure work together or create fully functional human being. 
The main hardware components of a computer are as under: 
1. System boards 
2. CPUs 
3. BIOS 
4. Memory /Storage
5. Input/output devices
6. Interfaces 
7. Display systems
8. Power System 
If you open any computer, you should be able to identify the above-mentioned components inside

.


अन्य विषय 
अन्य जानकारी


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