Unit-VIII Information and Communication Technology (ICT)  

          ICT: General abbreviations and terminology.

                                 Fundamentals of Computer 

Computers have now become an integral part of our daily life. People use computers for a variety of reasons and purposes. Be it education, business, entertainment, communication, government service or transportation, computers are inevitable today.

Data and Information

Data denotes raw facts and figures such as numbers, words, amount, quantity etc. that can be processed or manipulated. Information is a meaningful and processed form of data.

Data processing

Data processing refers to the operations or activities performed on data to generate information. So we can say that information is the result of data processing.

Functional units of a computer

Computer consists of some functional units namely Input Unit, Central Processing Unit (CPU), Storage Unit and Output Unit. Each of these units is assigned to perform a particular task.

1)-Input unit 

The collected data and the instructions for their processing are entered into the computer through the input unit. They are stored in the memory (storage unit). The data may be in different forms like number, text, image, audio, video, etc. A variety of devices are available to input the data depending on its nature. Keyboard, mouse, scanner, mic, digital camera, etc. are some commonly used input devices. In short, the functions performed by input unit are as follows: 1. Accepts instructions and data from the outside world. 2. Converts these instructions and data to a form acceptable to the computer. 3. Supplies the converted instructions and data to the computer for processing.

2. Central Processing Unit (CPU)

 The CPU is the brain of the computer. In a human body, all major decisions are taken by the brain and other parts of the body function as directed by the brain. Similarly, in a computer system, all major computations and comparisons are made inside the CPU. It is also responsible for activating and controlling the operations of other units of the computer. The functions of CPU are performed by three components - Arithmetic Logic Unit (ALU), Control Unit (CU) and registers.

                           a. Arithmetic Logic Unit (ALU) 

The actual operations specified in the instructions are carried out in the Arithmetic Logic Unit (ALU). It performs calculations and logical operations such as comparisons and decision making. The data and instructions stored in the storage unit are transferred to the ALU and the processing takes place in it. Intermediate results produced by the ALU are temporarily transferred back to the storage and are retrieved later when needed for further processing. Thus there is a data flow between the storage and the ALU many times before the entire processing is completed.

                                b. Control Unit (CU) 

Each of the functional units has its own function, but none of these will perform the function until it is asked to. This task is assigned to the control unit. It invokes the other units to take charge of the operation they are associated with. It is the central nervous system that manages and co-ordinates all other units of the computer. It obtains instructions from the program stored in the memory, interprets the operation and issues signals to the unit concerned in the system to execute them. 

                                  c. Registers 

These are temporary storage elements that facilitate the functions of CPU. There are variety of registers; each designated to store unique items like data, instruction, memory address, results, etc.

 3. Storage unit 

The data and instructions entered in the computer through input unit are stored inside the computer before actual processing starts. Similarly, the information or results produced after processing are also stored inside the computer, before transferring to the output unit. Moreover, the intermediate results, if any, must also be stored for further processing. The storage unit of a computer serves all these purposes. In short, the specific functions of storage unit are to hold or store: 

1. data and instructions required for processing. 

2. intermediate results for ongoing processing. 

3. final results of processing, before releasing to the output unit. 

The storage unit comprises of two types as detailed below:

 Primary storage: It is also known as main memory. It is again divided into two - Random Access Memory (RAM) and Read Only Memory (ROM). RAM holds instructions, data and intermediate results of processing. It also holds the recently produced results of the job done by the computer. ROM contains instructions for the start up procedure of the computer. The Central Processing Unit can directly access the main memory at a very high speed. But it is costly and has limited storage capacity.

 Secondary storage: It is also known as auxiliary storage and it takes care of the limitations of primary storage. It has a huge storage capacity and the storage is permanent. Usually we store data, programs and information in the secondary storage, but we have to give instruction explicitly for this. Hard disk, CDs, DVDs, memory sticks, etc. are some examples. 

4. Output unit 

The information obtained after data processing is supplied to the outside world through the output unit in a human-readable form. Monitor and printer are the commonly used output devices. The functions performed by output unit can be concluded as follows: 1. Receives the results produced by the CPU in coded form. 2. Converts these coded results to human-readable form. 3. Supplies the results to the outside world. 

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