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    Computer Generations and

    Classifications

    First generation

    Second generation

    Third generation

    Fourth generation

    Moores law

    Classification of computers

    By Trupti V.G,Asst. Prof, PESIT

    BY PRADYUMNA S A

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    First generation of computers

    First electronic computer- 1946 by a team Eckert andMauchly. It was called Electronic Numerical

    Integrator and calculator (ENIAC)

    Vacuum tube switching devices and small memory.

    Stored programming- John Von Neumann.

    EDSAC(Electronic Delay Storage Automatic

    Calculator)- 1st computer that used stored

    programming concept Table 1

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    Second generation of computers

    Invention of transistors made of germanium

    semiconductor material.

    When compared to vacuum tubes:

    They were reliable since they had no filaments to burn.

    Less space and power. 1/10thpower of tubes.

    Switching from 0 to 1 was faster.

    Cheaper than vacuum tubes.

    Magnetic cores for storage- tiny rings made of

    ferrite

    Table 1

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    Third generation of computers

    Germanium transistors replaced by silicontransistors.

    Integrated circuits ICs consisting oftransistors,

    resistors, capacitors grown on a single chip ofsilicon and wired interconnection between

    components.

    Main memory size reached 4MB

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    Fourth generation of computers

    Advent of microprocessor chip

    Magnetic core was replaced by semiconductor

    memories.

    semiconductor memories-16MB.

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    Moores Law

    1965: George E. Moore predicted on data

    available at that time, that the density of

    transistors in integrated circuits will double at

    regular intervals of around 2 years.

    The prediction was found to be accurate.

    The number of transistors per integrated circuit

    chip has approximately doubled every 18 months,

    this observation has been called Moores law.

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    In 1970 there were around 1000 transistors placed in an

    integrated chip whereas now there are nearly 1 billion

    transistors are placed in a chip and still the researches are

    going on to increase the number.

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    Classifications of computers

    Pocket or hand held PCs:

    Used as Fax, mobile phone. OS: Windows CE

    Simputer: Simputer is a mobile handheld

    computer.

    Open source OS: Linux

    Laptop PCs: less power, portable

    Personal Computers: Desktop machines

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    Workstations: Processor speed is 10 times more than PCs. High end computers for scientific applications.

    They are commonly connected to a local area network.

    Workstations offered higher performance than desktopcomputers, especially with respect to CPU and graphics,

    memory capacity, and multitasking capability. Operating system: UNIX

    Servers: Systems that provide services.

    They are used for specific purposes such as high performancenumerical computing, web page hosting, e-mail service,database store

    Usually connected to network.

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    Thin clients:

    It is a computer or a computer program which depends

    heavily on some other computer (its server) to complete

    its task.

    its a terminal to access a server(s).

    Advantages:

    Cheaper than desktops

    software cost is lower as they do not have native OS, virus

    protection and application software.

    Disadvantage:

    Dependence on network,

    Cannot be used as independent computer

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    Mainframe computers:

    Are computers used primarily by corporate and governmental

    organizations for critical applications, bulk data processing suchas census, industry and consumer statistics, enterprise resource

    planning, and transaction processing.

    Expensive

    Faster and larger than workstations Manufacturers of mainframes: IBM, Hitachi

    Operating system: extensive service such as user

    accounting, file security, control. They are reliable

    compared to PCs. Ex: z/OS

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    Supercomputers:

    They are fastest computers used for intensive numerical

    calculations.

    are used for a wide range of computationally intensive

    tasks in various fields, including quantum

    mechanics, weather forecasting, climate research, oil and

    gas exploration, designing aircrafts