OSI Reference model

OSI Reference model

OSI Stands for open system interconnection model,

It was developed by International standards Organization(ISO) in 1984.The OSI model describes seven layers that computer systems use to communicate over a network.

The OSI model helps users and operators of computer networks:

 ■Understand and communicate the process followed by components communicating across a network.

 ■ Determine the required hardware and software to build their network.

 ■  perform troubleshooting ,by identifying which network layer is causing an issue and focusing      

       efforts  on that layer.

There are seven types of OSI reference Model:

1.Physical Layer: 

       ■ It specifies how many No of pin, plug, socket to connect computer.

       ■ Single specification

       ■ It specifies media is guided or unguided.

       ■ Topology (Star, Ring, Bus, mesh)

       ■  HUB and Repeater works on this layer.

       ■  It simply transmit Raw bit data .

       ■   It totally deal with hardware devices.

2.Data Link Layer:

       ■ Framing done at this layer.

       ■  Node to Node error control.

       ■Node to Node flow control.

       ■Bridge and switch device works on this layer.

       ■Physical addressing (MAC ,address size 48BIT)

3.Network Layer:

       ■ logical addressing (IP address size IPV4-32BIT, IPv6128BIT)

       ■  Congestion control.

       ■  Routing 

       ■   Router operation on this layer.

4.Transport Layer:

        ■  Segmentation and Reassembly.

        ■   End to End error control.

        ■    End to End flow control.

        ■    Destination Search.

        ■   TCP(Transmission control protocol)

5.Session Layer:

       ■  Dialogue control

       ■  Token Management.

       ■   log information

6.Presentation  Layer:

       ■ Encryption a

nd Decryption

       ■ Compression and Decompression.

7. Application Layer:

        ■ Email, Telnet, FTP works on this layer.

                                 

      

Computer Generation

 Computer Generation

It means enhancement in hardware technology .Each generation defined by a significant technology development that changes fundamentally how computer's operate .less expensive efficient and robust machine .

There are different types of computer Generation:

1.First generation computer(1942-1956)

⇒The period 1942 to 1956, roughly considered as the First generation of computer.

⇒The working technology of first generation computer was vacuum tubes.

⇒Magnetic drums are uses for memory, first generation computer uses machine level language.

⇒The input of this system was based on punched cards and paper tape, however ,the output was displayed on printouts.

⇒The changes of hardware failure is very high.

⇒Generated large amount of heat.

⇒It takes large amount of electricity.

⇒Ac is mandatory, Bulky in size etc.

⇒ The first generation computers worked on binary-coded concept ( Language of 0-1)

Example:

 ENIAC(Electronic Numerical Integrator and Computer)

UNIVAC(Universal Automatic computer)

2.Second generation computer(1959-1965):

⇒The second generation uses Assembly level language or High level language

     like FORTRAN, COBOL.

⇒Reliable in comparison to first generation computer.

⇒Smaller size as comparison to first generation computer.

⇒Generated less amount of heat as comparison to first generation computer.

⇒Consumed less electricity as compare to first generation computer.

⇒ Still very costly.

⇒It is faster than first generation computers.

Some popular computer of this generation :

◼ IBM   1620 

◼IBM    1604

◼IBM    7094

◼IBM    3600

3.Third generation computer(1965-1971):

⇒ The period  of third generation computer was from 1965 to 1971.

⇒The working technology of third generation computer was integrated circuit.

⇒Pascal ,Basic ,Algol high level language were used during third generation computer.

⇒More reoviral then other to generation.

⇒Smaller in size generated less amount of heat require less mountainous.

⇒consumed less electricity.

⇒Sported High level language.

⇒IBM-360,PDP(personal data processer)

⇒TDC-316 are some popular example of third generation computer.

4.Fourth generation computer(1971 -1980):

⇒ The period of Fourth generation computer was 1971 to 1980.

⇒ The working technology of fourth generation computer is microprocessor.

⇒ A microprocessor chip is made from hundreds of Integrated circuits constructs on a single silicon             chip.

⇒ Computer of fourth generation used very large scale integrated circuit.

⇒ Fourth generation computer became more powerful compact reliable and affordable.

⇒ In this generation science showing read time Network and distributed operating reacting system               Where used.

⇒ All the high level language like C,C++, Q-Basic ,VB(Visual Basic).

⇒ Concept of Internet was introduce.

⇒ Pipeline processing is also introduced in fourth generation computer.

⇒ very small size.

⇒ Great development in the fields of network.

Example of fourth generation computer:

 

◼IBM -4341

◼DEC-10

◼STAR-1000

◼PUP- 11

             

    5.Fifth Generation computer(1980  to till that):

⇒ The period of Fifth generation computer is 1980 to till that.

⇒ ULSI(ultra large scale integrated) technology is used in Fifth generation computer.

⇒ All the high level language like C, C++,Java, VB. Net  are used in this generation.

⇒ Development of natural language processing.

⇒ More user friendly interfaces with multimedia features.

⇒ Ability of very powerful and compact computer at cheaper rate.

⇒ This generation is based down parallel processing Hardware and AI(Artificial intelligences).

     Artificial intelligence is a very broad category in computer science that incorporates various other            technologies.

     Some of the main elements in AI include the following:

   ■Robotics

   ■Neural networking

   ■Game playing

   ■Natural language understanding and generation.

   ■ Development of advanced systems that can take decisions on real-life situations

   

   Various types of computer exist in this generation, which are given below:

    1.Desktop

    2.Laptop

    3.Notebook

    4.Ultra book

    5.Chrome book

       Classification of Generation of computers

   Generation of computer                   Generations timeline                                Evolving hardware

1. 1st generation                                    1942-1956                                                     Vacuum tubes
2. 2nd generation                                    1959-1965                                                       Transistor 

3.3rd generation                                      1965-1971                                                      Integrated circuit 

4.4th generation                                      1971-1980                                                      Micro processor

5.5th generation                                      1980-Present & Future                                    Artificial                                                                                                                                                         intelligence   

        

 

Basic operation of computer

Basic operation performed by computer:

᩿Inputting

᩿Storing 

᩿Processing 

᩿Out putting

᩿Input interface/output interface

   

  Hello friends, I would like to explain  a New topic "Basic operation of computer".

 if you read this article carefully you will understand all about what is computer operation?

There are five basic operation performed by computer:

1.Inputing:

                The process of entering data and instruction to the computer is called inputting.in other words

An input is a data that is entered into or received by a computer is called inputting.

2.Storing:

                 Before actual processing start data and instruction enter to the computer must be stored somewhere inside the computer. similarly results produced by the computer are required to restored before it is paned to the output unit. the intermediate result produced by the computer must also be stored  processing .

3.Processing:

                  The task of performing calculation and comparison are known as processing .CPU stands for central processing unit. CPU is a responsible for processing.

  CPU consist following thing:

᩿ALU(Arithmetic Logic unit):   ALU is the place where actual execution of the instriction takes place during the processing operation.

᩿CLU:  ALU doesn't know what should be done with the data like output unit doesn't know when the result should be display.

It manages and co-ordinate the entire system.

4.Out putting:

               The process of giving final result to outside world is called out putting. This include data produced at a software level. such as the result of a calculation or at a physical level such as printed document.

ex-Printer, monitor, speaker, plotter etc.

5.Input interface:

                    The process of converting user acceptable format into machine acceptable forms is responsible for input interface.

 ᩿Out put interface: It is responsible for converting machine acceptable format into user acceptable format.

                                

What is computer?

What is Computer:

 Computer is a programmable device or electronic device .It accept data supplied by the user. it gives output according to user requirement.

Generally it means to calculate or programmable machine. computer can not do anything without a program. It represent the decimal numbers through a string of Binary digits.

               Charles Babbage is Called the Grand father of the computer

                                                

History of Computer

  The first computer was invented in the 1820s by  Charles Babbage .However the first electronic digital computer were developed between 1940 and 1945 in the united states and in the united kingdom. The history of computer hardware covers the developments from simple devices to aid calculation, to mechanical calculators, punched card data processing and on to modern stored program computers. The tools  or mechanical tool used to help in calculation are called calculators while the machine operator that help in calculations is called computer.

                       Computer works in IPO cycle:

I-Input

P-Process

O-Output

It perform both type of operation  Arithmetic as well ass logical operation.

Characteristics of computer

1.Speedc

2.Versatality

3.Accuracy

4.Power of remembering

5.No tiredness

1.Speed: 

            It is a very fast device .the computer takes a fraction of second to perform any operation . A powerful computer is capable of performing  about 3-4 million simple operations per second. 

 A computer is very speed as compare to  men.

2.Versatality:

                  versality is one of the most wonderful things about the computer.one moment it can do any one operation and next moment if can perform any other operation.

a computer is capable of performing almost any task according to given instructions.

3.Accuracy:

              the accuracy of computer is very high and the degree of a particular computer depends upon its design. but for a particular computer, each and every calculation is performed with the same accuracy.

4.Power of remembering:

                                  It is capable for remembering information about data .The computer can store and recall the information at any time because of the presence of the  secondary storage devices, but this is not possible with the human beings.

Although the brain of human being can store unlimited data .

5.No tiredness:

                It is no tiredness because A computer is a electronic or programmable device.

you can do different types of  operation on computer without any problem. It is always useful when can you use it.

       computer organization:*

The internal arrangement of different computer of computer system is called computer organization.

      

            Computer Architecture:*

The internal design of different component of computer system is called computer architecture.