EARLIES CALCULATOR
taken from Wikipedia


Humanity has used devices to aid in computation for millennia. The earliest counting device was probably some form of tally stick; later record keeping aids include Phoenician clay shapes which represented counts of items, probably livestock or grains, in containers. Another example is a device for establishing the checkered cloths of the counting houses served as simple for enumerating stacks of coins, by height. A more arithmetic-oriented machine is the abacus. The earliest form of abacus, the dust abacus, has been used in Babylonia and perhaps earlier times. The ancient Egyptian bead and wire abacus dates from 500 BC.[citation needed]
A number of analog computers were constructed in ancient and medieval times to perform astronomical calculations. These include the Antikythera mechanism and the astrolab from ancient Greece (c. 150-100 BC). These devices are usually regarded as the first analog computers. Other early versions of mechanical devices used to perform some type of calculations include the Planisphere; some of the inventions of Abū Rayhān al-Bīrūnī (c. AD 1000); the Equatorium of Abū Ishāq Ibrāhīm al-Zarqālī (c. AD 1015); and the astronomical analog computers of other medieval Muslim astronomers and engineers.
John Napier (1550–1617) noted that multiplication and division of numbers can be performed by addition and subtraction, respectively, of logarithms of those numbers. While producing the first logarithmic tables Napier needed to perform many multiplications, and it was at this point that he designed Napier's bones, an abacus-like device used for multiplication and division.
Since real numbers can be represented as distances or intervals on a line, the slide rule was invented in the 1620s to allow multiplication and division operations to be carried out significantly faster than was previously possible. Slide rules were used by generations of engineers and other mathematically inclined professional workers, until the invention of the pocket calculator. The engineers in the Apollo program to send a man to the moon made many of their calculations on slide rules, which were accurate to three or four significant figures.
In 1623, Wilhelm Schickard built the first digital mechanical calculator and thus became the father of the computing era.[1] Since his machine used techniques such as cogs and gears first developed for clocks, it was also called a 'calculating clock'. It was put to practical use by his friend Johannes Kepler, who revolutionized astronomy.
An original calculator by Pascal (1640) is preserved in the Zwinger Museum. Machines by Blaise Pascal (the Pascaline, 1642) and Gottfried Wilhelm von Leibniz (1671) followed. Around 1820, Charles Xavier Thomas created the first successful, mass-produced mechanical calculator, the Thomas Arithmometer, that could add, subtract, multiply, and divide. It was mainly based on Leibniz's work. Mechanical calculators, like the base-ten addiator, the comptometer, the Monroe, the Curta and the Addo-X remained in use until the 1970s.
Leibniz also described the binary numeral system, a central ingredient of all modern computers. However, up to the 1940s, many subsequent designs (including Charles Babbage's machines of the 1800s and even ENIAC of 1945) were based on the harder-to-implement decimal system.