INTRODUCTION TO COMPUTER SYSTEM

INTRODUCTION TO COMPUTER

DEFINITION:- Computer is an electronic device, which is used to compute or proceed and organize store information and used to process data. It is also use for arithmetic calculation. A computer is an electronic device, operating under the control of instructions stored in its own memory that can accept data as a input, process the data according to specified rules and regulation and produce result or information known as a output, and store the information for future use.  Computer can also be defined in terms of functions it can perform.  A Computer can - 1.) Accept data  2.) Store data  3.) Process data as desired4.) Retrieve the stored data as and when required and  5.) Print the result in desired format.  Enroll in our C Programming Language Course for FREE.

BASIC COMPUTER OPERATIONS :- A computer performs basically five major operations or functions irrespective of their size and make the simplification the task. These are :1) It accepts data or instructions by way of input,2) It stores the data,3) It can process data as required by the user,4) It gives results in the form of output, and5) It controls all operations inside a computer.

We discuss below each of these basic 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 inside the computer. 

 

FUNCTIONAL  OPERATIONS OF COMPUTER

    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.    

TYPES OF COMPUTER/ CLASSIFICATION OF COMPUTER:-

There are three types of classification of computer-

    1.Based on Technology

2.Based on Principal

3. Based on Size, cost & function

1. Analog Computers:-

The analog computers represent data in the form of continuous electrical signals having a specific magnitude. These computers are very fast in their operations to be carried out at the same time. They are a powerful tool to solve differential equations.

Analog computers represent variables by physical quantities. Thus any computer which solve problem by translating physical conditions such as flow, temperature, pressure, angular position or voltage into related mechanical or electrical related circuits as an analog for the physical phenomenon being investigated in general it is a computer which uses an analog quantity and produces analog values as output. Thus an analog computer measures continuously. Analog computers are very much speedy. They produce their results very fast. But their results are approximately correct. All the analog computers are special purpose computers.

 2. Digital Computers:-

The digital computer is also known as the digital information processing system, is a type of computer that stores and processes data in the digital form. Therefore each type of data is usually stored in these computers in terms of 0s and 1s. The output produced by these computers is also in the digital form.

Digital computer represents physical quantities with the help of digits or numbers. These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.

Ex – Desktop pc

3. Hybrid Computers:-
The hybrid computer is a combination of analog computer and digital computer because it encompasses the best features of both these computers. Therefore the hardware components of hybrid computers are usually the mixture of analog and digital components. The hybrid computer is also less expensive than the digital computers.

Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system. Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world. The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form.

2). Based on Application:-Different computers are designed for a different purpose so that they can perform their tasks according to their capabilities. On the basis of different applications or purpose, computers can be classified into the following categories:

    1. General purpose computers:-They are designed in such a manner that they can work in all environments. The general purpose computers are versatile and can store a number of programs meant for performing distinct tasks. The general purpose computers are not efficient and consume a large amount of time in generating the results. Ex-Micro computer Minicomputer.

 2. Special purpose computers:-They are designed in such a manner that they can perform only a specified task. The special purpose computers are not versatile and their speed and memory size depend on the task that is to be performed. The special purpose computers are efficient and consume less amount of time in generating the results. Ex. Main frame & Super computer .

   3) Based on size and Capabilities:-

Computers differ from each other in terms of their size, shape, and weights. Each type of computers perform some unique functions and can be employed in the fields suited to them. On the basis of size, shape the computers can be classified into the following categories.

 1. Microcomputers:-
A microcomputer is a small and cheap digital computer that is designed to be used by individuals. It is built around a microprocessor, a storage unit, and an I/o channel. The microcomputers are generally in the form of PCs, workstations and notebook computers.

The computer uses Microprocessors are called Micro computer. The first microprocessor computer was built of 8-bit chip. Means 8-bit of data can be send for process into C.P.U. Further it improved to 16-bit system. Which is known as 8086 and 8088,80486. These computers were first introduced by Intel Corporation. The storage capacity of this computer is about 1 GB and onwards. The latest  computers are of 32-bit and are known as Pentium I/II/III/IV etc. These computers are widely used for general purpose works or house hold works. It also known as Personal Computer (PC).

  Example: Personal Laptop, PC etc.

2. Mini Computers:-
A minicomputer was first introduced in the year 1960 by Digital Equipment Corporations(DEC). They were called minicomputers because of their smaller size than the other computers of those time.

  Mini computers are the multi-user systems. It is mainly used in a official networks or like that networks. Where some terminals are connected trough this computer. Mini computers have large storage capacity and have high C.P.U speed. These computers are generally 8/16 bit computers.

Mini computers are smaller than mainframes, both in size and other facilities such as speed, storage capacity and other services. They are versatile that they can be fitted where ever they are needed. Their speeds are rated between one and fifty million instructions per second (MIPS). They have primary storage in hundred to three hundred megabytes range with direct access storage device.  

Example- PDP-8,PDP-II etc.

  3. Mainframe Computers:-

A mainframe computer is a very large computer that is employed by the large business organization for handling major applications such as financial transaction processing.

  Example: IBM z Series, System z9 and System z10 servers.

  4. Super Computers:-
A super computer is the fastest type of computers that can perform complex operations at a very high speed. The super computer was first presented in the year 1960s by Seymour Cray at Control Data Corporation(CDC). They are more expansive than the other categories of computers.

 Large scientific and research laboratories as well as the government organizations have extra ordinary demand for processing data which required tremendous processing speed, memory and other services which may not be provided with any other category to meet their needs. Therefore very large computers used are called Super Computers. These computers are extremely expensive and the speed is measured in billions of instructions per seconds.

Example: Cray, Param, jaguar, roadrunner .

     5. Embedded Computers:-

Embedded computers are fixed into products designed to perform specific functions. Such products are mostly household appliances and cars. Embedded computers are put into household appliances and electronic devices like dishwashers, microwaves, washing machines and coffee makers in order to perform designated tasks. Electronic devices around the home like watches, answering machines, sewing machines, DVD players, television sets, pen, necklace and watch recorders and so forth, also make use of embedded computers. Cars also use embedded computers to assist with diagnosing faults, notifying the user of important conditions like under inflated tires, an oil filter that need changing, and controlling the use of airbag and other safety devices.

v  Example of Embedded Computers
ATM Digital Cameras Microwave ovens Factory controllers Washing machine Calculator TV remote Medical imaging Robots Traffic lights Anti-lock banking system	Microwave ovens Digital cameras Mp3 players Digital watches Mp3 player video games consoles Printers GPS receivers Dishwashers Thermostats