INTRODUCTION TO COMPUTER 

A computer is an electronic data processing machine or device that performs processes, calculations and operations based on instructions provided by a program. Computers are now used vastly in every field of life. The advancement in computer caused advancement in knowledge, science and technology. Today, computers are used in fields of business, industry, education, banking, transportation, research, explorations, media, entertainment , etc. 

1.1.1 Evolution Of Computers 

The computers which we see today are modern shape of computers which have been evolved since centuries. The evolution of computers is generally divided in following three eras. 

(i) Mechanical Era (Dark Age) 

Men have been trying to invent machines that can solve mathematical problems. In mechanical era, human became successful to make simple machines that could help performing simple arithmetic operation, in other words computing. These machines were manually operated since the electricity was not invented. Some of the important machines of this era are: 

(a) Abacus (3000 B.C.) Abacus was invented about 5000 years ago. It is also known as counting frame. Abacus is still used to teach basic arithmetic operations to the students. Abacus is considered as first computer prototype. 

(b) Napier’s Bones (1612 A.D.) Scottish mathematician John Napier developed Napier’s Bones, in 1612.It is also called Napier’s Rods. It was a small machine that contained ten rods. The rods were made up of bones, wood or metal. Napier’s Bones was used for multiplication and division. 

(c) Slide Rule (1622 A.D.) English mathematician William Oughtred invented a Slide Rule. This was basically a pair of two moveable rules placed side by side. They had a standardized set of markings called scales. These scales were used for mathematical computations. Slide Rule was used to multiply and divide numbers. The modern slide rules are still used in some countries. 

(d) Pascaline or Pascal’s Calculator (1642 A.D.) French mathematician Blaise Pascal invented a mechanical calculator which was called Pascaline. He developed this machine to help his father who was a tax collector. Pascaline can perform addition and subtraction by eight figures. User had to adjust wheels in order to perform these calculations. 

(e) Leibniz’s Calculator (1694 A.D.) Leibniz’s Calculator was developed by the German mathematician Gottfried Wilhelm Leibniz. It was also called stepped reckoner. It was the first calculator that could perform all four basic arithmetic operations; addition, subtraction, multiplication and division. 

Babbage’s Difference and Analytical Engines (1822 and 1837 A.D.) 

Charles Babbage was an English mathematician and mechanical engineer. He is known as Father of Computer because he developed the first complete computing machine. His first invention was Difference Engine. It was an automatic mechanical calculator. Difference Engine was a large machine, made of metal and was powered by steam. The Difference Engine had storage (mechanical memory) that could hold the data temporarily for processing and to store results. It was used to allow a user to enter calculations and get printed results. The Difference Engine worked on difference equations. Then, Charles Babbage designed but could not build a very big machine in 1837. This was named Analytical Engine. The proposed design included an ALU with basic programmatic flow control. It was programmed using punched cards and contained integrated memory. Historians consider it to be the first design concept of a general-purpose computer because of its comprehensive design.

Electro-Mechanical Era (Middle Age) 

This era starts from the mid of 19 century. In this era scientists became able to develop faster and more accurate computing machines as they were powered by steam and electricity. One of such machines was Tabulating Machine. 

Herman Hollerith’s Tabulating Machine (1890 A.D.) 

It was invented by American inventor Herman Hollerith in 1890.Hollerith’s first tabulator was used for the U.S. 1890 Census. Because of Hollerith’s tabulating machine census data took only six months to compile, which was very fast as compared to previous U.S. census in 1880 which took 7 years to be completed. Hollerith Tabulating Machine became very famous and used in many offices of U.S. Government. 

(iii) Electronic Era (Modern Age) 

The advancement in the vacuum or electron tube gave birth to the electronic era. In this era the true computers were invented which worked on the principle of input, store, process and output. Continuous advancement in electronic engineering increased efficiency and speed of computers considerably. The electronic era may be categorized in generations on the basis of core technology used to build computers. 

(a) First Generation of Computers (1940 to1956) Based on vacuum tubes, first generation computers were very large in size. This generation computers used machine language (i.e. 1’s and 0’s).Magnetic drums were used as primary internal storage medium and punched cards for input. In this generation mainly batch processing operating system was used. Computers of this generation were primarily used for scientific and research purposes. Electronic Numerical Integrator and Calculator (ENIAC), Universal Automatic Computer (UNIVAC) are examples of fi rst generation computers.