Let’s us discuss the origin of computer system or evolution of computer system in early 19th century. They are as under:

- Abacus
- Napier’s bone
- Slide Rule
- Pascal’s Calculator
- Leibniz’s Multiplication and Dividing Machine
- Difference Engine
- The Analytical Engine
- Mechanical and Electrical Calculator
- Modern Electronic Calculator

### 1. Abacus

- Abacus was developed in China around 3000 year ago.
- It was used as a calculating device and was much popular during Ming Dynasty of China ruling during the period (1368 AD to 1644 AD).
- It is also known as a counting frame which is used to perform arithmetic operations.
- Now a days it is used as a calculating tool for teaching children to count numbers.
- A skilled abacus can perform calculations as fast as a hand held calculator.

### 2. Napier’s bone

- John Napier was a great mathematician who developed mechanical device for multiplication purpose in 1617 A.D.
- The device which he invented is known as Napier’s bone which main task was to calculate products and quotients of numbers.
- The method was based on lattice multiplication, and was also called ‘rabdology’, a word invented by
**Napier**himself. - Napier’s “bones” are set of eleven rods through which products and quotients of large numbers can be obtained.
- The sticks were called as “bones” because they were made up of bone of ivory.

### 3. Slide Rule

- Slide Rule was developed by a great English mathematician E. Gunter.
- Slide Rule machine was capable of performing operations such as: addition, subtraction, multiplication and division.
- Slide Rule machine was also capable of performing exponents, logarithms, roots and trigonometry expressions.
- Here slide rule is not meant for measuring length or drawing straight lines, but it was generally used for multiplication and division purposes besides other computational work.

### 4. Pascal’s Calculator

- Blaise Pascal was a French mathematician and modern scientist who have developed and build calculator.
- Pascal’s calculator is also known as arithmetic machine or Pascaline.
- He developed a machine which was capable of adding and subtracting numbers.
- The calculation was done with the help of wheels, gears and cylinders.
- Pascal invented this calculator at a very early age of 18 to help his father to perform large complex and tedious accounting task.

### 5. Leibniz’s Multiplication and Dividing Machine

- Gottfried Wilhelm von Leibniz was a great German mathematician and philosopher designed a calculating machine called Leibniz’s Multiplication and Dividing Machine in 1671.
- This calculating machine was expanded on Pascal’s ideas and called as Step Reckoner in 1673.
- Like Pascal, Gottfried Leibniz was a seventeenth century scientist who arrived at a conclusion that mechanical device can perform mathematical calculations and saves labour too.
- Leibniz suggested that binary numbers are easy to handle for electronic machine because it can be easily represented in on or off state of a switch.
- Although Leibniz has idea for binary number system but it was not implemented in this machine rather he used decimal form to represent numbers.

### 6. Difference Engine

- Difference Engine was the first step towards the idea of a computer.
- It was developed by a great English mathematician and professor, Charles Babbage.
- Charles Babbage is also known as “
**father of the computer**“. - Charles Babbage had simplified the complex mathematical calculations by breaking the logic into simple operations which was carried out by automatic machine.
- Difference engine prepares numerical tables using mathematical technique which is known as method of difference.
- While developing Difference Engine Charles Babbage arrived at a conclusion that performing multiplication and division mechanically was a difficult task.
- Therefore, after giving ten years on difference engine development and to overcome these problems he moved to the development of Analytical Engine.

### 7. Analytical Engine

- Analytical Engine was a development from the Difference Engine by Charles Babbage
- It is marked as a progression from the arithmetic calculation to general purpose computation.
- It has may essential features which were found in the modern digital computer.
- Analytical Engine had a “
**Store**” (memory) where data and results could be held and a separate “**Mill**” (processor) where arithmetic processing was performed. - It was also capable of performing conditional branching, looping statement and micro programming features with parallel processing.

### 8. Mechanical and Electrical Calculator

- Mechanical computer was designed to perform all sorts of mathematical computations.
- Later, rotating part of mechanical calculator was replaced by electric motor that’ s why it is called as mechanical and electrical calculator.
- Mechanical calculator used short-cut multiplication methodology, and had ten-keys 0-9 to perform arithmetic operations and some serial-entry types had decimal-point keys.
- Electronic calculator used electron tubes for performing its work.
- Full-keyboard machines, were motor-driven ones, were built around 1960.
- Major manufacturers were Mercedes-Euklid, Archimedes, and MADA in Europe; in the USA, Friden, Marchant, and Monroe were the principal makers of rotary calculators with carriages.

### 9. Modern Electronic Calculator

- Modern electronic calculator replaced the electron tubes which were bulky in size.
- Electron tubes were replaced by transistors and as a result the size of calculator became fairly small.
- Modern electronic calculator was capable of performing mathematical calculations and mathematical functions.
- It was also capable of storing data permanently.
- Modern electronic calculator contains a keyboard with buttons to perform arithmetical operations.
- Modern calculators can even perform complex and sophisticated arithmetic computations like square roots, logarithms and trigonometric equations.