Leonardo da Vinci 1452 - 1519 First mechanical calculator may have been conceived by Leonardo da Vinci around 1502. In 1967 scientists working in the National Library of Spain, Madrid had stumbled upon 2 unknown works of Leonardo da Vinci, now know as the “Codex Madrid”. There was much excitement regarding this discovery and public officials stated that the manuscripts"was misplaced". In 1968 IBM hired Doctor Roberto Guatelli, a famous world expert of Leonardo da Vinci, to build a replica.

From the Greek word “ABAX”, meaning “calculating board” or “calculating table”. The abacus is a calculator whose earliest known use is circa 500 B.C. by the Chinese civilization. The abacus as we know it today, appeared circa 1200 A.D. in China. Its Mandarin name is “Suan Pan” which means “calculating plate” or calculator. It is often referred to as the “first calculator” because it was used as a mathematic model for early electronic calculators.

Update: Researchers have long suspected the ancient clockwork device was used to display astronomical cycles. A research team (Mr Freeth and his colleagues) has now found that one of the dials records the dates of the ancient Olympiad. The ancient Olympiads, called the Panhellenic Games, comprised four games spread over four years. The Antikythera Mechanism was found in swallow water off the coast of the Greek island of Antikythera, and that is how it got its name.

Ancient times - The abacus is the main aid to calculation. BC100 - Greek Antikythera Mechanism. 1500 - Leonardo da Vinci conceived the first mechanical calculator. 1600 - Napier’s bones invented by John Napier for multiplication, based on the ancient numerical scheme known as the Arabian lattice. 1620 - William Gunter developed a logarithmic rule for multiplication and division using dividers, which was the forerunner of the slide rule. 1622 - William Oughtred invented the circular slide rule, and in 1633 described the rectilinear version.