Computer

Computer have made great in roads in everyday in our life and thinking. They are put to use for all sorts of application ranging from complex calculations in the field or frontline research, engineering simulations down to teaching, printing books and recreational games. The ease with which computers can process data, store and retrieve it painlessly has made them inevitable in office and business environments. The areas of application of computers are confined only by limitations on human creativity and imagination. In fact any task that can be carried out systematically can be performed by a computer. Therefore, it is essential for every educated person today to know about a computer, its strength, its weakness and its internal structure.

Computer- 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 time faster than human 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 space aircrafts etc.

A computer is used essentially as a data processor. The term data and information are very commonly used. We must understand clearly between the two.

Data: Data in computer terminology means raw facts and figures. For example ‘Mohan’, 1977, ‘A’, -162.19, + 75.2 are data.

Information: It means what e=we get after processing data (meaningful data). Data are aggregated and summarized in various meaningful ways to form information. For example ‘Mohan, whose roll number is 1977, has got grade A’ is an information as it is conveying some meaning.

Functioning of computer- Before we know the functioning of computer, let us understand the way we function. To understand this, let see some examples.

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

(ii)You want to talk to one of your friends. His phone number is 9042564846. So you dial up the number and speak to your friend.

(iii)Your mom has to make tea. So she takes some things (ingredients) i.e. ¾ cup of water, ½ teaspoon tealeaves, ½ teaspoon sugar and ½ cup of milk. She makes the tea by following certain steps like boiling water, adding tealeaves, sugar and milk. Finally you get prepared tea.

Above examples illustrate the way human being function. Consider all the three examples. There are certain things common in them. In all the examples certain things were needed to work upon, the actual work was then carried accordingly and finally the result was obtained.

Following table explains it

INPUT, PROCESS AND OUTPUT

All the above examples undergo three stages. The first stage (things to work upon) is called input stage. The second stage (the actual work being performed) is called process stage and third stage (the result) is called output stage. Certain input is necessary to accomplish a task; a process is carried out on the input to obtain the output.

Every task follows this input-process-output (IPO cycle in short). A computer is not exception to this rule. A computer also follows the I-P-O cycle i.e. it needs certain inputs, carries out a process and produces the output.

FUNCTIONAL COMPONENTS OF A COMPUTER

Since a computer follows input-output-process cycle the first stage is performed in computer in computer by input unit, second stage is performed by output unit. Thus the basic unit of a computer is as shown in below figure.

INPUT UNIT------------------------------CENTRAL PROCESSIG UNIT (CPU) ---------------------------OUTPUT UNIT

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MAIN MEMORY

(BASIC STRUCTURE OF COMPUTER)

The main memory holds the input and intermediate output during the processing.

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 (OMR), optical character reader (OCR), joystick etc.

The input unit is responsible for taking input and converting it in to computer understandable form (the binary code). Since a computer operates on electricity, it can understand only the language of electricity i.e. either ON or OFF or high voltage or low voltage. That means a computer can understand two stages ON/OFF or HIGH/LOW voltage or the binary language that uses just two symbols: 1 for ON and 0 for OFF.

An input unit takes the input and converts it in to binary form so that it can understand by the computer.

Consider the input of three earlier examples. All the inputs consisted of data (on which the action is to performed) as well as the instruction (the action to be taken)

INPUT COMPRISED OF DATA AND INSTRUCTION

On the same line, the computer input also consists of data and instruction. For example, if the given input to the computer is Add 2 and 3 and instruction is Add. Similarly, if the given input ‘Manisha’ then the data consists of ‘Manisha’ and instruction is print.

CENTRAL-PROCESSING UNIT -The CPU is the control centre for a computer. It guides, directs 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 its control unit (CU) and arithmetic logic unit (ALU).

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 takes place and the result is put back in the memory. The same way other arithmetic operations are performed.

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

Control unit (CU) – The CU controls and guides the interpretation, flow and manipulation of all data and information. The CU sends control signal until the required operations are done properly by the ALU and memory. Another important function of CU is the program execution i.e. carrying out all the instruction stored in the computer. 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 i.e. which operation is to be performed. Then they asked operation is carried out. After the work of this instruction is completed, control unit sends signal to memory to send the next instruction sequence to CU.

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 performed by the out 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 of electronic binary signals which needs conversion in some form which can be easily understand by human beings i.e. characters, graphical or audio visual. This function of conversion is performed by output signal is performed by output units. Some popular output devices are VDU (Visual display unit), printer, plotter, speech synthesizer and coder etc.

THE MEMORY

Well, if a computer has a brain (CPU), it must have a faculty which we call memory. Indeed, it does posses a memory, however, the memory of a computer is most unlike human memory. A human being can remember stored information for a long period whereas a computer cannot. Its memory is temporary (volatile), it cannot remember anything after it gets switched off.

The memory of a computer is more like a predefined working place, where it’s temporarily keeps information and data 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.

The memory of a computer is often called as main memory or primary memory. It is generally the third component of CPU. The memory of a computer can be thought of as cells. The memory cell may also be defined as a device which can store a symbol selected from the set of symbols.

Each of these cells is further broken down in to smaller parts known as bits. A bit means a binary digit i.e., either 0 or 1. A number of bits are used to store data instructions by their combination.