Understanding what a computer is and it’s impact on our lives is very important especially now that we are in Information Age. The tool for harnessing information is computer. The computer has been described in various ways- an intelligent machine, a robot, an idiot, a magic machine etc. what is true about the computer is that it has no intelligent of its own but if properly instructed, can perform numerous tasks with an unimaginable speed, consistency and accuracy. We can then define a computer as an electronic device operating under stored-programme concepts that accepts data as input, processes the data and produces result as output.

Owing to the usefulness and application of computers to every area of our lives-business, education, medicine, commerce etc, the knowledge of computers is a must for every individual that wants to remain relevant to the present society.


No one person invented the computer. The computer evolved over hundreds of years ago. Before machines existed,people found ways to calculate e.g. with fingers, arranged stones in piles or rows, and made scratches on the ground.

As the need to calculate increased, people sought ways to help them. The oldest known mechanical aid for calculation is the Abacus. The Abacus is a portable device that consists of beads strung on wires or wooden rods. With it one can rapidly and accurately add and subtract numbers. The Abacus is still used in some parts of the world day. As civilization advanced the need for more advanced computing tools arose e.g. Money lenders had to computer interest on loans. In 1642 Blasé Pascal invented the first mechanical calculating machine called pascal’s Adding Machine. This machine was made of a combination of interlocking wheels and gears. The numbers 0 to 9 were printed on the Wheel. When the first wheel made a complete turn from 0 to 9 it automatically cased 2 wheel to advance to the next number. When the second wheel moved past 9, it caused the third wheel to turn and so on. This machine was used only to add and subtract. Abacus and pascal’s adding machines were limited in capability. A German mathematician, Gottfried von Leibnitz in 1694 invented a stepped Reckoner. He improved the pascal’s adding machine, instead of using wheels and gears, he used cylinders.

The stepped Reckoner could handle addition, subtraction, multiplication, division and square root. Less than a century later, people were again seeking a better calculating machine. About 1812, Charles Babbage a professor of mathematics conceived the idea of the modern computer, He devised a machine that could compute mathematical table automatically. The automatic calculator was called a difference engine since it used a difference method of computation. He conceived another type of machine called an Analytic engine in 1838′ Which he worked on most of his life without completion. According to his design, this would have been a steam powered mechanical computer. It would have been to receive instructions, perform calculations and produce printed output. Programs for the analytical engine would be coded and punched into cards. The concept of punched card was not new but Babbage was the first person to apply it to a computing machine. Babbage borrowed the idea of punched-card input from Joseph jacquard, a French weaver. In 1801 the weaving loom marker Joseph Jacquard developed a method of “programming “a loom to automatically weave complex patterns, using card in which holes were punched. Different cards with different patterns of holes produced different woven design. Charles Babbage may have been the first to link punched cards and computers but it was Dr. Herman Hollerith (a Statistician) who put the card to practice. Hollerith invented a machine to help the U.S census Bureau count the population. Every ten years the government conducts a census. The 1880 census took about 8 years to tabulate the results. With Hollerith’s tabulating machine the 1890 census was completed in less than three years. This machine used punched cards to store information for calculating and manipulation. It was not until the first half of the twentieth century that the first true computer appeared. These machines were more than mechanical calculators that could add, subtract and multiply, they were capable of solving complex problems.

In 1930, an American scientist Vannevar Bush built the first calculating machine. Bush’s machine was called Differential Analyzer. It was the first analog computer. Analog computers computed by measuring the continuous change in a physical quantity e.g. temperature. This machine could solve complex mathematical problems very quickly. It ran on electricity and used vacuum tubes to store information. It had so many parts that it filled an entire room.

In 1937, Howard Aiken of Harvard University designed a machine called an Automatic Sequence Control Calculator Known as Mark I. This machine prepares mathematical tables by automatically performing a set of sequences of arithmetic operation. The Mark I was not fully electronic in operation however, it was electro-mechanical that is it used electronic signals in combination with mechanical gears, switches and wheels. Mark I was huge, it was over 50 feet long and 8 feet high and it had more than 750,000 parts. J. Prester Eckert and John W. Mauchly designed computer in 1946 called ENIAC (Electronic Numerical Integrator and Calculators). It was faster than Mark I although it was more enormous. ENIAC was 100 feet long and occupied 3,000 cubic feet of space. It used 18,000 vacuum tubes. These tubes enabled the computer to store and process data electronically rather than mechanically ENIAC’s Vacuum tubes presented problems of their own. They occupied a lot of space and generated a great deal of heat. They were not as reliable as today’s electronic components.

Using ENIAC to perform calculations was much more complicated than using a modern computer. Programming instructions had to be given manually by plugging in hundreds of wires.

Once a program was carefully wired in the order of instructions could not be changed until the whole program had run. Each new program required another new combination; therefore creating and running even simple programs took quite long.

Von Neumann originated the ideal of storing programs in computer memory. A stored-program computer represented a big step forward from ENIAC and other earlier machines. It does not need to be rewired manually for each new task therefore it was faster and more flexible than earlier computers. The first stored program machine was EDSAC (Electronic Delay Storage Automatic Calculator) invented in 1949. Today all computers are stored-program computers.

In 1951, John Mauchly and J. Presters Eckert built their own stored-program computer called UNIVAC, wich was sold to the Census Bureau. After that, many other models of the UNIVAC were made sold to business organizations. Thus, UNIVAC became the first commercial computer. It was also the first computer to use magnetic tape for input instead of punched tape or card.


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