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Sunday, December 19, 2010

1st GENERATION COMPUTER (1945 -1955)

          The development of electronic computers had clearly helped to visualize the concept of computer. The computer system has teken a big leap forward with each technological breakthrough during the development process. The functions performed by the computers and speed of their operations have been changing. There have been a great variation in size and cost of the computers.
Technological breakthrough in hardware and software resulted into more and more advanced computer system belonging to one particular technological class (or trend) is said to belong to a particular computer generation.


FIRST GENERATION COMPUTER ( 1945 - 1955)


          First generation computer used vacuum tubes as memory devices. The computers were large size and very costly and used the assembly language for programming.
  • Colossus  was  the first  electronic  computer  of  this  era.  It's  every  aspect  was  kept secret by British Government.
  • In 1945,  Von  Neumann  Architecture was introduced. Eckert and Mauchley began working  on  EDVAC  (Electronic  Discrete Variable Automatic  Computer)  but  it  never completed. Later Von Neumann developed his own EDVAC (IAS machine).
  • In 1946, the development of ENIAC (Electronic Numerical Integrator and Computer), which was started in 1943, was completed.
  • Some other  computers of this generation are  UNIVAC,  MARK  II,  MARK  III,  Z2, Z4, SSEC (Selective Sequence Electronic calculator) and some IBM computers series such as IBM 604, IBM 650, IBM 701, IBM 702.
  • In 1954, first version of FORTRAN (Formula Translator) was published by IBM.

2nd & 3rd - GENERATION COMPUTER (1955 - 1965 - 1974)


Second Generation: Transistors and Batch System (1955 - 1965)

          Second generation computers used transistors as CPU components and ferrite cores for main memory and magnetic disk drum/tapes as secondary memory.

  • Some  high  level  languages  introduced  in  this  generation  are  FORTRAN,  ALGOL, BASIC and COBOL.
  • Transistors increased the processing power of computer and decreased the size, cost and power usage as well. Thus, vacuum tubes computers were obsolete.
  • Some  of  the  computers  in  this  generation  are  TX-0  (Transistorized  experimental Computer),  TX-2,  NEAC   1101  (from  NEC),  PDP   series  computers  from  Digital
  • Company, IBM series computers such as IBM 709, IBM 1400 series etc               CDC (Control  Data  Corporation)  built fast computers called supercomputers  -  CDC 6600. 


Third Generation: Integrated Circuits and Multiprogramming (1965 - 1980)

The invention of silicon ICs (Integrated Circuits) allowed dozens of transistors to be put on a single chip. They used magnetic disks as memory devices but later they were replaced by semiconductor memories. Some of the major achievements are:

  • Multiprogramming was introduced.
  • The computers were more powerful and smaller than previous generations.
  • OSes like UNIX OS, system /360 OS, IBM MVS, BSD was developed.
  • Some of the programming languages built in this generation are: ada, PASCAL, BCPL,
  • SHRDLU, FORTRAN 66 and 77, SEQUEL (nowadays SQL)
  • Intel introduced its microprocessors - Intel 4004, Intel 8080, 8086, 8088.
  • Examples  of  third  generation  of  computer are  Apple  computers,  CDC's  Cyber-  175 and PDC series, STAR 1100 etc.

 
 

4th & 5th – GENERATION COMPUTER (1975 – 1990 – Present)

Fourth Generation: Very Large Scale Integration (1975 to present)

The  fourth  generation  computers  use  VLSI  chips  for  both  CPU  and  memory.  The  VLSI technology allowed millions of transistors on a single chip. This high density of fabrication directly affected the size and sped of the machine. With heavy drop in price, it was feasible for  single individual  to  have  his/her  own  computer.  Some of the achievements  in  this generations are:
  • RISC (Reduced Instruction Set Computers) was introduced.
  • Superscalar computers and personal computers were introduced.
  • User friendly and fast computer with virtual technology is available in the market.
  • Progress in neural  network and AI has helped to produce intelligent machines that the  fifth  generation  computers  are  under  development  stage.  Highly  developed can learn, adopt and analyze the knowledge itself.
  • Improvement on distributed system, and network communication system.
  • Examples of fourth generation computers are: Apple Macintosh, IBM PCs etc.



Fifth Generation: (Present and Beyond)

  • The fifth generation computers are under development stage. Highly developed countries such as have undertaken projects to design and develop such computers. These computers  will  use ULSI (Ultra  Large Scale Integration)  chips.
  • There will  be progress  on  intelligent  system  and  expert  system  to  develop  intelligent  computers which  can  have  vision,  learning  ability,  object  recognition  and  synthesis  ability, natural language understanding ability.
  • The  input  and  output  of  the  computes  will  be  in  the  form  of  speech  and  graphic

ANALYTICAL ENGINE

BABBAGE'S ANALYTICAL ENGINE
Babbage, still wanted to design a bigger machine, called an Analytical Engine. The idea of an Analytical Engine developed in 1833 was considered as a most significant step in the history of computers, because of his idea only, the dream of modern computer has come true. That is why he is famous as "Father of Computer".
In addition to the arithmetic functions like addition, subtraction, multiplication, division, finding square root and percentage, Babbage wanted his Analytical machine to control itself (i.e. capacity to make decisions). He also wanted the machine to store numbers from where he could draw desired numbers. The machine would be able to store a thousand 50-digit numbers. It would be able to add or subtract two 50 digit numbers in one second and multiply two 50 digit numbers in one minute.
Babbage intended to have his machine to have a mechanism to input data and output the results. He wanted to input data with the help of punched cards and the output to be printed on copper plates. Babbage's analytical engine and modern day computers are similar in their structure. This engine had four major units.
1. Store     : A memory or store which could store data and intermediate results.
2. Mill       : An arithmetic unit which was called a 'Mill'. It could perform calculations.
3. His machine had mechanism having gears and shafts by which data and results were transferred between the store and the mill which is similar to the control unit of today's computer.
4. Input and Output devices.
Technology of the time of Babbage was not advanced enough to make gears, shafts and other mechanical devices. So the dream of Babbage could not become true in his life time.

EDVAC & UNIVAC

EDVAC (Electronic Discrete Variable Automated Computer)
          In 1945, a noticeable improvement in the development of the computer took place when John Von Neumann, the Hungarian mathematician genius developed the idea of Stored Program Concept. He proposed a new computer called EDVAC (Electronic Discrete Variable Automated Computer) which would utilize his stored program concept.
The stored program concept would overcome the drawbacks of ENIAC. People would not have to rewire the machine to go to a different program, the machine itself would read the instruction from the Computer’s storage to switch or change to a new program. According to Newman, EDVAC would use Binary Number system instead of Decimal Number System used in ENIAC.
Prof. Maurie Wilkes used the similar program concept to design the computer called EDSAC (Electronic Delay Storage Automatic Computer). EDSAC was developed completely in 1949.


UNIVAC (UNIVersal Automatic Computer)
          After developing ENIAC, Mauchly and Eckert formed their own company in 1946. This company built a new computer called UNIVAC-I (UNIVersal Automatic Computer-I) in 1951. UNIVAC was delivered to the Census Bureau. Business organizations too started using UNIVAC. Hence, it was the first commercially used electronic computer in the world.
IBM company paid much attention to the development trends of the computers and it could grasp the opportunity of the need of computer in the world. It started manufacturing series computers. The IBM 650 series computer started its service in Boston in 1954. Other companies also emerged during this time.

ENIAC ( Electronic Numerical Integrator And Computer)

          In the true sense, the first electronic computer was developed by John Mauchly and John Presper Eckert. It was developed at the university of Pennsylvania and called ENIAC (Electronic Numerical Integrator And Computer). ENIAC used high-speed vacuum tubes (switching devices). The high speed operation of the computer in the world was first experienced with ENIAC. It could add two numbers in 200 microseconds and multiply two numbers in 2800 microseconds. Number of vacuum tubes used was 19,000. It occupied an area of 150 square meters.
In fact, ENIAC was the result of the efforts made by US armed force to complete new trajectory tables for use in World War-II. But ENIAC was completed in 1946. So they could not make use of it in war.
Note: Trajectory Table:- The table show the firing rangers and paths of different types of artillery in different geographical settings from energy conceivable angle.
Even though it was so fast, there were few drawbacks in ENIAC. Those were:
1.       Large amount of heat generated by vacuum tubes needed a cooling facility.
2.       Storage capacity was small.
3.       Whenever the program is changed, the machine had to be rewired.

ELECTROMECHANICAL & ELECTRONIC COMPUTERS

ELECTROMECHANICAL COMPUTERS
    
   In the early part of twentieth century, tabulating machines were growing rapidly. Meanwhile, the computational need of the nations was also increasing. So, governments, universities, and research organizations were trying to find the solution to meet those needs.
In 1984, next important event occurred in history. The electromechanical computer was born with the development of MARK I by Howard Aiken and other was constructed MARK I at Harvard University under the sponsorship of IBM (International Business Machine).
The MARK I also known as the Automatic Sequence Controlled Calculator. It was 50ft. long and 8ft. high. It used electronic tubes and electrical relays.
MARK I took 41/2seconds to multiply two 23 digit numbers. It was able to produce ballistics tables that were used in connection with Second World War. The input device used was the punched paper tape.


ELECTRONIC COMPUTERS

          The age of electronic computer began after 1890 when vacuum tubes were introduced. Such tubes were thousands of times faster than the earlier electromechanical devices.
The first electronic digital computer was developed by John V. Attansoff and his student Clifford Berry. It was called Attansoff-Berry Computer (ABC computer).
ABC computer used vacuum tubes (electronic device) instead of electromechanical relays. It was comparatively very fast as compared to the previous computers.
ABC computer could not become popular because it could solve only certain type of problem and it used advanced electronic technology of that time.

PUNCHED CARD MACHINES

          Punched Cards were originally used by Joseph Marie Jacquard. Charles Babbage had used the punched cards and operated them by mechanical devices.


Dr. HERMAN HOLLERITH

          The first card machine which was electrically activated was used by Dr. Herman Hollerith to compute the statistics of the 1890 United States census. Hollerith was an American mechanical engineer and statistician, working for Census Bureau.
He used the punched cards to store data, with the holes  representing data values. After trying for several formats, Hollerith designed cards which were the size of a dollar bill. It had 288 locations for punching holes.
He developed an electromechanical tabulating machine for punched cards. In those machines all the data to be processed are keyed in cards. Because of his sincere efforts, the census of 1890 could be processed in one-third the time of 1880 census.
Hollerith's punched cards method became very popular and widely used. So he started his own company, Tabulating Machine Company in 1896, to manufacture both machines and cards. The interesting fact in the history of computers manufactures is that Hollerith's company was merged with other companies to form the International Business Machine (IBM) Corporation. Today, IBM is the leading company to manufacture the computers and develop software in the world.

GEORGE BOOLE

          George Boole, a British mathematician, introduced mathematics of logic known as Boolean Algebra. It laid the foundation of digital computers. Boolean considered two valued binary notation (i.e. 0 and 1) to represent any form of data. In fact, Boolean Algebra is very useful when we analyse or the design binary system.

DIFFERENTIAL ENGINE

BABBAGE'S DIFFERENTIAL ENGINE

          In 1812, another interesting development took place in the history of computers. Charles Babbage, an English Mathematician, invented the Differential Engine. Babbage is called his device a Differential engine because it was based on the difference tables of the squares of numbers. For example, the following table shows the level difference between values of Y in the formula i.e. Y=X2

Table showing Level difference

Value of X
Value of Y
1st level difference
2nd level difference
0
0
1
2
1
1
3
2
2
4
5
2
3
9
7
2
4
16
9
2
5
25
11
2


As shown in the table, the second level difference is constant (i.e. 2). Y can be found for any value of x by adding (for x=5) as:
y=2+7+16=25
Babbage wanted to calculate Polynomial functions using the method of differences but such machine was to have hundreds of gears, shaft and counters. Unfortunately, the differential engine was not completed.

 

HISTORY OF COMPUTING MACHINES

INTRODUCTION

          A computer is an invention of human beings to enhance their capabilities to accomplish tasks. Modern computers are developed after a gradual change over a long period of time.
Tribal life in ancient time required man to remember a lot of information, so an early man felt the need to count the things. Then he started counting using his own fingers. However, the limited number of fingers had made it difficult for him to remember more facts. Thus, he started different methods to count using stones, sticks, scratches on a rock or wall or a knot in a string. As a result, during fifth century Hindu philosophers were able to develop a new method of counting using the numbers (digits) 0 to 9. Since there are ten digits, the Arabic Number System method was called Decimal Number System of counting. Hence, the history of computer implies the gradual change in the concept over a long period of time. Under following titles, we have explain the history of computing machines from their early forms to the most modern high speed electronic computers.


ABACUS

          In early days, people used pebbles or beads on a counting board carry out simple calculations. This tool is called the Abacus. Its exact origin is unknown. It may have originated in China, Egypt and Greece during 5000 B.C. to 2000 B.C.
The abacus employs a positional number system (Place Value Notation). The value of a bead depends on its location, the majority of abacuses use decimal system. The abacus has several rows of beads string on rigid wires fixed in a rectangular frame. The beads on the rightmost wire represent ones, on the next adjacent wire towards left represent-tens; on the third wire representing hundreds, and so on. If an abacus has 11 wires the beads in the left most wire will have a place value of 1010. A bead is counted by moving the same towards the crossbar. A bead above the cross bar is equivalent to five of these below the cross bar.
An abacus can be used to add, subtract, multiply and divide. Even today the abacus is used in many parts of the world (example China). If the operator is a skilled one, the abacus could be as fast as a desktop calculator.


NAPIER'S BONE

          In 1614, John Napier, a Scottish Mathematician, first published the first table of logarithms. It was very helpful in simplifying multiplication of large numbers.
In 1617 Napier also developed a numbered rod in order to multiply, divide and extract roots, known as Napier's bone. It was called so because it was made up of strips of bones on which numbers were painted. By the combination of these bones, direct multiplication could be done.
The Napier's bone uses the principle of performing multiplication by the addition of logarithms.
Napier constructed his Napier's bone using nine pieces of card; each divided vertically into nine squares. Each square is divided diagonally from the top right hand corner to the bottom left hand corner.


SLIDE RULE

          In 1620, Slide Rule was developed by William Oughtred, UK which is an analog device. It used the principle of logarithms.
There are two graduated scales, one scale slides or slips upon the other. With the proper alignment of the two scales, it is easy to find the product, quotient or any other function simply by viewing on the scales.
Whenever the 1 of middle scale is aligned with 2 of the top scale, we can easily read the multiple of 2 along the scale. Similarly, the division may be performed.


PASCAL'S ADDING MACHINE

         Better techniques for keeping the records by hand along with specialized calculating device continued to be developed through the centuries. The first real calculating machine that could add and subtract was a mechanical calculator called Pascal's Adding Machine or Pascaline, invented by a French scientist Blaise Pascal in 1642.
Pascal's Adding machine consisted of toothed wheels or gears with each wheel or gear heaving digits 0 through 9 engraved on it. The addition or subtraction was performed by turning these wheels. The wheels were turned in such a way that when one wheel made a complete revolution, the next adjacent wheel towards the left made one tenth of a revolution. It could be said that wheels had different place values following the decimal number system.
This machine had the capacity to add or subtract 8 - Column numbers. The maximum number that it can add or subtract is up to 9,99,99,999 and it had an automatic carry generation capacity. The disadvantage of this machine was that it could add subtract, but it could not carry out multiplication and divisions.


LEIBNIZ'S CALCULATOR

          The first calculator that could perform automatic addition, subtraction as well as multiplication and division was developed by a German philosopher Gottfried Wilhelm Von Leibniz.
It worked on the principle that multiplication and division can be accomplished by repetitive addition and subtraction respectively.
In 1694, Leibniz modified his calculator. It was also known as Stepped Reckoner. It consisted of a drum upon which teeth were mounted, nine at one end. A gear wheel was positioned on the shaft mounted along the drum. The gear wheel could be moved to mesh in with the teeth of the drum at any position.
For example to multiply by 5, the gear wheel was moved 5 positions on the drum. One revolution of the drum moved the gear wheel through 5 teeth, two revolution through 10, and so on. The carry-over mechanism was also employed. Leibniz used the new concept of binary system in a calculating machine.


JACQUARD'S LOOM

          At the beginning of the nineteenth century (i.e. A.D. 1801), Joseph Marie Jacquard of France invented a punched card as an accessory to the loom. The punched card could automate the loom for  Weaving of intricate patterns. Thus, he could control the weaving loom through the set of holes in a card, which could store the instruction for the loom. The holes could allow the wires to pass through and cause the thread to be lifted (as the wires were attached to the wrap thread in a fabric). The jacquard's loom.