Generations Of Computers and their Evolutions  ?

FIRST GENERATION OF COMPUTERS (1949-55) :

    The first electronic computer was introduced in 1946 by a team led by Professors Eckert and Mauchly at the University of Pennsylvania in U.S.A.-This computer was called Electronic Numerical.integrator and Calculator (ENIAC). It used high speed vacuum tube switching devices. It had a very small memory and  was designed primarily to calculate the trajectories of missiles. 

The ENIAC added two digits in around 200 microseconds and multiplied in about 2800 microseconds. 

 IMPLEMENTATION OF PROGRAM LOOPS :

The first computer was designed and commissioned in 1949  at Cambridge University, U.K. under the leadership of Professor Maurice Wilkes. This computer called EDSAC (Electronic Delay storage Automatic Calculator) used mercury delay lines for storage.

    Early in the 1950s, stored programme electronic computers saw commercial manufacture. One of the early computers of this type was UNIVAC I built by Univac division of Remington Rand and delivered in 1951. This computer also used vacuum tubes.Vacuum tubes had a finite lifespan because they relied on filaments as an electron source. About 0.5 watts of power were consumed by each tube.. Computers typically used about ten thousand tubes. Power dissipation was very high. As a large number of tubes, each with limited life, was used in fabricating these computers, their mean time between failures was low - of the order of an hour. 

    Machine language was the primary programming language used at the time. The early 50s saw the invention of assembly language. Its initial applications were in science and engineering. With the advent of UNIVAC, the prospects of commercial applications of computers were perceived. The concept of an operating system had not yet emerged. By and large during this period one had to be a good electronics engineer, and understand the logical structure of a computer in great detail. One also had to know how to program an application in order to use a computer. tt was somewhat like the early days of motorcars when one had to be a good mechanic to be able to drive a car! 

 THE SECOND GENERATION (1956-65)  :

            A big revolution in electronics took place with the invention of transistors by Bardeen, Brattain and Shockley in 1947. Transistors made of germanium semiconductor material were highly reliable compared to tubes since transistors had no filament to burn, They occupied less space and used only a tenth of the power required by tubes. They could also switch from a Oto a 1 State in a few microseconds, about a tenth of the time needed by tubes. Thus switching circuits for computers made with transistors werg about ten times more reliable and ten times — cheaper than those using tubes. ' %

    Computer manufactures thus changed over to transistors from tubes. The second generation computers emerged around 1955 with the use of transistors instead of vacuum tubes in computers. This generation lasted till 1965. 

    Another major event during this period was the invention of magnetic cores for storage. Magnetic cores are tinny rings made of ferrite and can be magnetized.in either clockwise on anticlockwise direction. The two directions are used to represent a 0 and a 1. Magnetic cores were used to construct large random access memories. . 

Memory capacity in the second generation computers was about 100 kilo-bytes. 

     High level languages were developed as a result of improved computer reliability and vast amounts of memory being available. During this generation, Fortran, COBOL, Algol, and Snobol were developed. The second generation saw the emergence of effective batch operating systems, particularly those found on IBM 7000 series machines. 

 THE THIRD GENERATION (1966-75) :

    The third generation began in 1965 with germanium transistors being replaced by silicon transistors. Integrated circuits, circuits consisting of transistors, resistors and capacitors on a single chip of silicon eliminating wired interconnection between components emerged. Switching speed of transistors went up by a factor of 10, reliability increased by a factor of 10, power dissipation reduced by a factor of 10 and computer size was also reduced by a factor of 10. 

    There were significant imp ovements in design of magnetic core memories. The size of main memories reached about 4 Megabytes. Magnetic disk technology improved rapidly. 100 Megabytes on drive became feasible. 

     High level languages improved. Fortran! IV and optimizing Fortran compilers were developed. COBOL 68 was standardized  by the American National Standards Institute. PL/ 1 of IBM emerged and was quite a powerful language. 

 THE FOURTH GENERATION :

FIRST DECADE (1976-85)  -

     The fourth generation may be identified with the advent of _ the microprocessor chip. Medium scale integrated circuits yielded to Large and Very Large Scale Integrated circuits (VLSI) packing about 50000 transistors in a chip. Magnetic core memories were replaced by semiconductor memories. Disk memories became very large (1000 Mbytes/drive). The most ambitious language of.this period was ADA. Another important development was interactive graphic devices and language interfaces to graphic systems. 

Fourth generation saw the coming of age of UNIX OS and time-shared interactive systems. These systems became user-friendly and highly reliable. The effective cost of computing come down. Computers also became all pervading. ie | acing. 

SECOND PHASE (1985-2000) -

    The speed of microprocessor and the size of main memory and hard disk went up by a factor of 4 every 3 years. The alpha microprocessor chip designed by DEC in 1994 packed 9.3 million transistors in a single chip. It was driven by a 300 MHz clock and could carry out a billion operations per second. It had a built-in 64-bit floating point arithmetic unit, used 64-bit data and 64-bit address busses. 

    Microprocessors such as Pentium, Power PC, etc, are being used as the CPU of personal computers and portable laptop and palm held computers. 

    In the ared of languages, C language became popular. The C++ language emerged as the most popular object-oriented language. PROLOG was designed for logic-oriented specification language and MIRANDA, FP etc as functional specification oriented languages. With the emergence of distributed computers connected by networks considerable effort has gone into programming distributed: s#stems. A number of parallel computers were built but no commonly accepted standard parallel programming language has enmerged.

 THE FIFTH GENERATION  : 

     It is not yet clear what direction the fifth genération will take, It is estimated that by 2005 we may see computers of this generation. 

Even though computers in the last 50 years have become very fast, reliable and inexpensive, the basic logical structure proposed by Von Neumann has not changed. The basic block diagram of a CPU, memory and |/0 is still valid today. With the improvements in integrated circuit technology, it is now possible to get specialized VLSI chips at a low cost. 

 MOORE'S LAW  :

In 1965 Gordon E. Moore, one of the founders of Fairchild Semiconductors, (U.S.A), predicted, based on data available at that time, that the density of transistors in integrated circuits will double at regular intervals of around 2 years. Based on the experience from 1965 to date, it has been found that his ’ prediction has been accurate. In fact the number of transistors per integrated circuit chip has approximately doubled every 18 months. The observation of Moore has been called “Moore's Law”. The present generation microprocessor is already a 64bit processor with clocks in the range of 1 GHz to 2 GHz. 

Another interesting point to be noted is the increase in the disk capacity. In 1984 disk capacity in PCs was around 20 MB, whereas it is 20 GB today - a 250 fold increase in about 14 years again doubling every 20 months which is akin to Moore's Law. 

EVOLUTION OF COMPUTERS 

    The evolution of computer started from 16th century and resulted in the form that we see today. The present day computer, however, has also undergone rapid changes during the last fifty years. This period, during which the evolution of computer took place, can be divided into five distinct phases known as Generations ‘of Computers. Each phase is distinguished, from the other on the basis of the type of switching circuits used. 

FIRST GENERATION COMPUTERS 

    First generation computers used Thermion valves. These computers were large in size and writing programs on them was difficult. Some of the computers of this generation were

> ENIAC :

 It was the first electronic computer built in 1946 at University of Pennsylvania, USA by John Eckert and John Mauchly. It was named Electronic Numerical integrator and Calculator (ENIAC). The ENIAC was 30 to 50 feet long, weighed 30 tons, contained 18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and required 150,000 watts of electricity. Today your favourite computer is many times as powerful as ENIAC, still its size is very small. 

> EDVAC : 

It stands for Electronic Discrete Variable Automatic Computer and was developed in 1950. The concept of storing data and instructions inside the computer was introduced here. This allowed much faster operation since the computer had rapid access to both data and instruction. The other advantage of storing instruction was that computer could do logical decision internally. 

OTHER IMPORTANT COMPUTERS OF FIRST GENERATION 

> EDSAC: 

It stands for Electronic Delay Storage Automatic Computer and was developed by M.V. Wilkes at Cambridge University in 1949. 

> UNIVAC - 1 :

Eckert and Mauchly produced it in 1951 by Universal Accounting Computer setup. 

LIMITATIONS OF FIRST GENERATION COMPUTER :

    Following were the major drawbacks, of First Generation ee Computers -- 

1. The operating speed was quite slow. 

2. Power consumption was very high. 

3. They required large space for installation. 

4. The. programming capability was quite low. 

SECOND GENERATION COMPUTERS  : 

    Around 1955 a device called Transistor replaced the bulky electric tubes in the first generation computers. Transistors are smaller than electric tubes and have higher operating speed. They have no filament and require no heating. Their manufacturing cost was also very low. Thus the size of the computer got reduced considerably. 

It is in the second generation that the concept of Central Processing Unit (CPU), memory, programming language and input and output units were developed. The programming languages such as COBOL, FORTRAN were developed during this period. Some of the computers of the Second Generation were

> IBM 1620: Its size was smaller as compared to First Generation Computers and it was mostly used for - scientific purpose. 

> IBM 1401 : Its size was small to medium and it was used for business applications. 

> CDS 3600 : Its size was large and it was used for scientific purposes. 

THIRD GENERATION  COMPUTERS :

The Third Generation Computers were introduced in 1964. - They used Integrated Circuits (ICs). These ICs are popularly known as Chips. A single IC has many transistors, registers and capacitors built on a Single thin slice of silicon: So it is quite obvious that the size of the computer got further reducéd. Some of the computers developed during this period were IBM-360, ICL-1900, IBM-370 and VAX-750. Higher level languages such as BASIC (Beginners All-purpose Symbolic Instruction Code) was developed during this period. 

Computers of this generation were small in size, low in’ cost, large in memory and very high in processing speed. 

FOURTH GENERATION COMPUTERS :

        The present day computers that you see today are the Fourth Generation Computers that started around 1975. Such a computer uses Large Scale Integrated Circuits (LSIC) ~ built on a single silicon chip called microprocessors. Due to the development of microprocessor it became possible to place computer's Central Processing Unit (CPU) on a single chip. These computers are called microcomputers. Later Very Large Scale Integrated Circuits (VLSIC) replaced LS!Cs. 

Thus the computer which was occupying a very large room - in earlier days can now be placed on a table. The Personal Computer (PC) that you see in today is a Fourth Generation Computer. 

FIFTH GENERATION COMPUTER 

These computers are still in design phase and are called Fifth Generation Computers. The speed will be extremely high in Fifth Generation Computer. Apart from this it would perform parallel processing. The concept of Artificial _ Intelligence has been introduced to allow the computer to take its own aay oie still 9 developmental stage. 

This generation is based on parallel processing hardware and AI (Artificial Intelligence) software. AI  interprets the means and method of making computers think like human . All the high-level languages like C and C++, Java, .Net etc., are using  in this generation of Computers and IoT devices .

Common AI includes −Robotics , Neural Networks, Game Playing, Development of expert systems to make decisions in real-life situations, Natural language understanding and generation, machine learning ,deep learning ,natural language processing etc.

Some computer types of this generation are - Desktop ,Laptop, tablets, NoteBook ,UltraBook ,Quantum computers ,workstations , etc.

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