Napier's Bones
John Napier, the Scottish mathematician developed a mechanical device to handle engineering and mathematical calculations in 1617.
Pascal Machine
in 1642, a 19 years son of a French tax collector called Blaise Pascal helped his father by developing pascal device to accomplish tax calculation. The machine consisted of gears, wheels and dials.
Leibniz's Machine (1673)
Gottfried Leibniz, a German philosopher and mathematician developed leibniz device for multiplication purposes. Gottfried Leibniz lived between 1646-1716
Babbage Analytical Engine
in 1822, Charles Babbage proposed a machine for solving differential equations call a difference engine. this machine would perform calculations and print out results automatically. He abandoned his difference engine after 10 years to developed the first general purpose computer, which is called Analytical engine Charles Babbage lived between 1792 - 1871, he is popularly known as the father of computer
The Tabulating Machine
Herman Hollerith, An American Inventor, invented the first electrical computer (the tabulating machine) to face out the challenges of census computation in U.S.. census of 1880 was difficult to calculate, which took about seven years to complete the computations. with Hollerith machine, the 1890 U.s. Census were completed in just six weeks instead of seven years under the conventional method. Herman Hollerith lived between 1860 - 1929