HISTORY OF COMPUTER

an electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program.

The slide rule, also known colloquially in the United States as a slipstick,^[1][2] is a mechanical analog computer.^{[3][4][5][6][7]} As graphical analog calculators, slide rules are closely related to nomograms, but the former are used for general calculations, whereas the latter are used for application-specific computations.

The slide rule is used primarily for multiplication and division, and also for functions such as exponents, roots, logarithms, and trigonometry, but typically not for addition or subtraction. Though similar in name and appearance to a standard ruler, the slide rule is not meant to be used for measuring length or drawing straight lines.

or Numerical wheel calculator:-Blaise Pascal (1623 -1664)

in 1642 invented the first adding machine called Pascaline. The brass rectangular box used eight moveable dials

to add and sum up of eight figures long using base 10. It can perform all the four arithmetic operation with

previous unheard speed