History of computer could be traced back to the effort of man to count large numbers. This process of counting of large numbers generated various systems of numeration like Babylonian system of numeration, Greek system of numeration, Roman system of numeration and Indian system of numeration. Out of these the Indian system of numeration has been accepted universally. It is the basis of modern decimal system of numeration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Later you will know how the computer solves all calculations based on decimal system. However, you will be surprised to know that the computer does not understand the decimal system and uses binary system of numeration for processing.
We will briefly discuss some of the path-breaking inventions in the field of computing devices.
Calculating Machines
It took generations for early man to build mechanical devices for counting large numbers. The first calculating device called ABACUS, was developed by the Egyptian and Chinese people.
The word ABACUS means calculating board. It consists of sticks in horizontal positions on which are inserted sets of pebbles. A modern form of ABACUS is shown in Fig. 1.2. It has a number of horizontal bars each having ten beads. Horizontal bars represent units, tens, hundreds, etc.
Napier’s bones
English mathematician John Napier built a mechanical device for the purpose of multiplication in 1617 AD. The device was known as Napier’s bones.
Slide Rule
English mathematician Edmund Gunter developed the slide rule. This machine could perform operations like addition, subtraction, multiplication, and division. It was widely used in Europe in 16th century.
Pascal’s Adding and Subtraction Machine
You might have heard the name of Blaise Pascal. He developed a machine at the age of 19 that could add and subtract. The machine consisted of wheels, gears and cylinders.
Leibniz’s Multiplication and Dividing Machine
The German philosopher and mathematician Gottfried Leibniz build around 1673 a mechanical device that could both multiply and divide.
Babbage’s Analytical Engine
It was in the year 1823 that a famous English man Charles Babbage built a mechanical machine to do complex mathematical calculations. It was called difference engine. Later he developed a generalpurpose calculating machine called analytical engine. You should know that Charles Babbage is called the Father of computers.
Mechanical and Electrical Calculator
In the beginning of 19th century the mechanical calculator was developed to perform all sorts of mathematical calculations and it was widely used till 1960. Later the routine part of mechanical calculator was replaced by electric motor. It was called the electrical calculator.
Modern Electronic Calculator
The electronic calculator used in 1960s was run with electron tubes, which was quite bulky. Later it was replaced with transistors and as a result the size of calculators became too small. The modern electronic calculators can compute all kinds of mathematical computations and mathematical functions. It can also be used to store some data permanently. Some calculators have inbuilt programs to perform some complicated calculations.