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

1. Abacus
2. Napier’s bone
3. Slide Rule
4. Pascal’s Calculator
5. Leibniz’s Multiplication and Dividing Machine
6. Difference Engine
7. The Analytical Engine
8. Mechanical and Electrical Calculator
9. 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.