The first electronic computers were developed in middle of 20th century. They were of the size of a large room and consumed power as much as several present personal computers do. Modern day computers are made up of integrated circuits or chips which have eased our life in many ways. Many of us think that  personal computers are the only computers but the definition of a computer is a device which performs calculations and executes the list of instructions called program. From MP3 to fighter aircraft and from toys to industrial robots are most numerous embedded computers.  Infact, computer is  any programmable electronic device that can store, retrieve, and process data.

Thirst for invention for computer started from a desire to club two technologies: Automated calculation and Programmability.  The name computer suggests that this is a device for calculation but variance between a calculator and computer is the ability of programming.

In early period there were many devices invented for the purpose of calculation such as abacus, slide rule. Later calculator was invented. Subsequently many attempts were made by several scientists to invent a device which can perform both the activities. Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions. This became the essence of programmability.

The “castle clock”, an astronomical clock invented by Al-Jazari in 1206, is regarded as earliest programmable analog computer. The length of day and night could be re-programmed to compensate for the changing lengths of day and night throughout the year. In 1801 a Frenchman, Joseph-Marie Jacquard has invented a loom powered by water that weaves by reading punched holes stored on small sheets of hardwood. These plates are then inserted into the loom which reads the pattern and creates the weave. Later after a period of 36 years Charles Babbage who is known as father of computers conceptualized and invented fully programmable mechanical computer. Computer invented by Babbage was a poor communicator and record-keeper. The incomplete project of Babbage was sufficiently developed by Ada Lovelace. She actually developed a device that would translate short stories mechanically. She is regarded as first programmer.

In the late 1880s, Herman Hollerith invented the recording of data on a machine readable medium. These were the punch cards similar to the ones used 80 years earlier to create weaves by Joseph Marie Jacquard. To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith’s company. This Hollerith Tabulating Company is a forerunner of today’s IBM.

By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter. Part of the problem lies in the international situation that makes much of the research secret. Other problems include poor record-keeping, deception and lack of definition.

During first half of the 20th century many more models of modern computers were made but they were not as accurate as the modern digital computer. In 1936 Alan Turing widely regarded as father of modern computer provided the concept of algorithm and computation with his Turing machine. With this he was regarded as the most influential person of the 20th century by the” Times” and it stated “The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine”.

In the year 1937 George  Stibitz who is internationally regarded as father of modern digital computer  invented and built a relay-based calculator he dubbed the “Model K” (for “kitchen table”, on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability. In 1930’s and 1940’s more powerful and flexible computing systems were invented by adding  the key features which we enjoy now in our modern computers. Notable inventions among them were:

  • Konard Zuse’s electromechanical “Z-machines”. This is later regarded as world’s first operational computer.
  • Atansoff-Berry computer (1941) which used vacuum tubes for computation.
  • The secret British Colossus computers which were used to break German war time codes.
  • Harvard Mark’s large scale electro mechanical computer in 1944.

The U.S. Army’s Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse’s Z3 of 1941 used electromagnets instead of electronics). ENIAC was designed by John Mauchly and J. Presper Eckert of the Moore School, they got help from John von Neumann and others. In 1944, Havard Mark I is introduced. Based on a series of proposals from Howard Aiken in the late 1930′s, the Mark I computed complex tables for the U.S. Navy. It uses a paper tape to store instructions. Aiken hired Grace Hopper as one of three programmers working on the machine. Thomas J. Watson Sr. played a pivotal role involving his company, IBM, in the machine’s development. Von Neumann proposed the concept of a “stored program” in a paper that is never officially published. And at last work on ENIAC completed in the year 1946.

Basically ENIAC had many problems. But these flaws were rectified by many scientists who developed ENIAC. Computers using vacuum tubes as their electronic elements were in use throughout the 1950s. John Bardeen, Walter Brattain and William Shockley were the scientists who developed transistors. These scientists received Nobel Prize in Physics in the year 1956.The first transistorized computer was demonstrated at the University of Manchester in 1953. As a result by the 1960s vacuum tubes had been largely replaced by transistor-based machines, which were smaller, faster, and cheaper to produce, required less power, and were more reliable. In 1956 FORTRAN is introduced, it took three years for this compiler to be developed. Two additional languages, LISP and COBOL, are added in 1957 and 1958. Other early languages include ALGOL and BASIC. ALGOL is the basis for many of today’s languages though it is not used widely.

Integrated circuits are introduced by two men, Jack Kilby and John Noyce, actually they worked independently. Fairchild Semiconductor introduced another integrated circuit. Within ten years all computers used these instead of the transistor. In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. In 1975 the first personal computer is marketed in kit form. The next year Apple started marketing PC’s, also in kit form. It includes a monitor and keyboard.

By the late 1970s, personal computer exploded on the American scene. Microsoft, Apple and many smaller PC related companies were formed.  By 1977 stores began to sell PC’s. Continuing today, companies strive to reduce the size and price of PC’s while increasing capacity. Entering the fray, IBM introduced it’s 2nd PC in 1981 as the first failed. ‘Time’ selects the computer as its Man of the Year in 1982. Many products such as video recorders contained dedicated computers called microcontrollers, and they started to appear as a replacement to mechanical controls in domestic appliances such as washing machines.

The 1980s witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the households.

The modern computer which was invented by contributions of several scientists is useful to people in many ways by providing various opportunities such as Internet, word-processing, digital video or audio composition, desktop publishing, mathematical calculation, E-learning etc. they are used in several fields such as medical, aero space, sports, robotics, defense, etc. It is being used in every aspect of human life. Computers have leapfrogged the human society into another league. The growth and development of computer technology is a continuous process. Costs are plummeting . Computing capacity is increasing at an unprecedented pace. The developments in tele communications that facilitated connectivity between two computers has unveiled the computer based virtual age. The myriad uses of computer make this instrument inseparable part of modern human life.

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