This is the earliest counting device. It was invented 2000 years before. It has two sections -Heaven and Earth. The beaded strings are kept inside the 'abacus. On each string of earth, there are 5 beads with a value equal to 1 and in the heaven; there are 2 beads with a value of 5 each. The bar which divides heaven and earth is known as mid bar.
John Napier was a Scottish Mathematician. In 1614 he developed 11 sets of bones on which numbers were engraved. These sets of bones were set used for calculation. The bones were set together to find the multiplication table also.
In 1620, William Oughtred developed a device called slide rule. Slide rule consists of two scales in which one scale slides over the other. This is an analog device and it was popular till 1970s.Pascal's Calculating MachineBlaise Pascal was a French Mathematician. in 1642 he developed a calculating device. This was very popular since that kind of calculating device was never built before. He invented this device to assist his father for calculating taxes. His father was tax superintendent at Royen.
Leibniz's Calculating Machine
Gottfried Leibniz was a German mathematician. In 1671 he developed a more powerful calculating machine which is called Stepped Reckoner. This could find the square roots also.
Charles Babbage is the most known person in the field of historical computing. He developed a machine called Analytical Engine. The concept used in his machine is the same as we have in modern computers. He could not complete his work due to the lack of technology and devices required for this machine at that time. His credit in the field of computing has honored him as the Father of Computer Science.
Dr. Herman Hollerith developed punched cards to solve the problem in American census in the year 1886-1887. The punched cards have holes at different places which are made by the machine called punch hoper. The hole represents data for tabulating machine which was developed by Hollerith himself.