**Introduction**

Evolution of computer exist when people lived on the earth for centuries without keeping records, but as social organizations such as tribes began to form, record keeping became necessary. The early man used stones and pebbles for counting cattle. Later the stones were replaced by sticks, marks on the earth, scratches and symbols on the stones, knots on the ropes etc. He found it very difficult to use these computing aids, because they required some physical efforts from him. Moreover, the computing speed was also very slow. This necessitates the development of new machines for better and faster computation. Let us now study some of the important developments that led to the development of modern computers.

**Chinese Abacus**

Abacus was one of the **earliest calculating devices** developed by Chinese **3000 years ago**. The Chinese abacus is called **suan pan**, which means counting board. It was made up of wooden frame with horizontal rods consisting of beads strung on them. It has two regions-heaven and earth separated by a mid-bar. There are two beads in the heaven which has the value of five and five beads on the earth which has the value of one. The calculation was done on abacus by shifting the beads from or towards the mid-bar. It is still used by millions of people throughout Asia to illustrate the principles of counting to school children.

**Napier’s Bones**

A Scottish mathematician called **John Napier** invented method of logarithm in **1614**. The use of logarithms enabled him to transform multiplication and division sums into problems of addition and subtraction. He called logarithms as artificial numbers in the beginning. In 1617, he developed a set of eleven calculating rods made of bone called Napier’s Bones. Each rod was further divided into 9 diagonal numbered parts. This device helped a lot in multiplication and division sums involving larger numbers.

**Slide Rule**

An English mathematician called **William Oughtred** constructed slide rule in **1620**. He invented both the standard rectilinear slide rule and the less commonly used slide rule. He used the principles of bones and logarithms. It has two movable graduated ruler kept side by side. Each ruler has been marked off in such a way that the actual distance from the beginning of the ruler is proportional to the logarithm of the number printed on the ruler. This device was used by engineers for multiplication and division.

**Pascaline**

A French Mathematician, **Blaise Pascal** invented the first mechanical calculating machine called Pascaline in **1642**. It was developed to help his father who was a tax collector in **calculating tax**. This machine worked with wheels, gears and dials. The numbers were entered by dialing a series of numbered wheels, where the movement of the wheels starts at 9 and moves to 0. The disadvantage of Pascal’s inventor was its limitations to addition and subtraction, while multiplication and division operations were done by performing a series of additions or subtractions.

**Stepped Reckoner**

A German mathematician, **Gottfried Von Leibnitz** invented Stepped Reckoner in **1671**. He improved the Pascaline by creating a machine that could perform all the four basic mathematical operations such as addition, subtraction, multiplication and division. It could evaluate square roots by series of stepped additions. His machine used stepped cylinders each with nine teeth of varying length and introduced a new concept called shift mechanism. Moving a digit to right or left is called shift. He achieved this through a series of sliders.

**Jacquard’s Loom**

**Joseph Marie Jacquard** was a French silk weaver. He invented automated loom in **1804** that used **punch cards** to weave and design patterns on cloth. The function of the loom depended upon the existence of holes on the card. Thus, Jacquard’s loom paved the way for the modern storage mechanism on punched cards and the binary coding system.

**Difference and Analytical engine**

**Charles Babbage** was an English born inventor and mathematician. He designed an automatic mechanical calculating machine called **Difference Engine in 1823** that could solve equations by calculating the differences between them. It was fully “automatic” in both calculating and printing output tables. It was controlled by a fixed instruction program that executed only in precise linear sequence.

This analytical engine, the first fully-automatic calculating machine. Conceived by him in **1834**, this machine was designed to evaluate any mathematical formula and to have even higher powers of analysis than his original Difference engine of the 1820s. Charles Babbage was honored as the **Father of Computers** as a result of his contributions to the basic design of the computer.

**Lady Augusta Ada Lovelace**

**Ada Lovelace (1815-1852**) was born Augusta Ada Byron, the only legitimate child of **Annabella Milbanke and the poet Lord Byron**. In 1843 she published a translation from the French of an article on the Analytical Engine by an Italian engineer, Luigi Menabrea, to which Ada added extensive notes of her own. The notes included the first published description of a stepwise sequence of operations for solving certain mathematical problems and Ada is often referred to as **‘the first programmer’**. In **1979**, the US Defense Department named a programming language ADA in her honor.

**George Boole**

George Boole was one of the greatest English mathematicians who contributed greatly to the study of **symbolic logic** during the **mid-19th century.** He was the inventor of mathematical logic. He represented logical expressions in mathematical form known as Boolean Algebra. It has laid part of the groundwork for modern computer science. Boole’s logic provided the framework for designing circuits with binary inputs (0’s and 1’s or false and true) to produce any combination of binary outputs. Since switching mechanisms at the time could only produce the two actions on and off, Boolean Algebra provide engineers a medium through which to communicate with their computers.

**Tabulating Machine**

Tabulating machine was an electromechanical machine designed to help in summarizing information and, later, accounting**. invented by Hollerith**, the machine was developed to assist process data for the 1890 U.S. Census. The Hollerith tabulating system was the primary to form practical use of the punch card in processing. Hollerith started his own business in 1896, founding the Tabulating Machine Company. In 1911, four corporations, including Hollerith’s firm, merged to make the Computing Tabulating Recording Company (CTR). In 1924, CTR was renamed International Business Machines (IBM.

Read more: **Generation of Computer**

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