A computer is a programmable device that can be store, retrieve, and process data. The term of computer performed numerical calculations using mechanical calculators, such as the abacus and slide rule. The mechanical device as they began replacing the human computers.

Today's computers are electronic devices that accept data (input), process that data, produce output, and store the results.

A computer is a device or machine that performs processes & calculations and operations based on instructions provided by a software or hardware program. It is designed to execute program, application and provides a variety of solutions by combining integrated hardware and software components.

First counting device was used by primitive people. They used by sticks, stones and bones as counting tools. As human technology improved with time more computing devices were developed And easily Calculate the Operation. Following of the popular computing devices starting with the first to recent ones are described below :

The abacus is a first computer device, Abacus also called as a counting frame. The abacus is a calculating tool that was first use in China, Europe, and Russia, countries before the adoption of the written Hinduâ€“Arabic numeral system. It is said that Chinese invented Abacus estimate around the 4,000 years ago.

It is invented by John Napier(1550-1617) of Merchiston, It was a manually-operated calculating device.In this calculating tool used 9 different ivory strips And bones marked with numbers to divide and Multiply. The tool became known as "Napier's Bones". It was also used the first machine to the decimal point.

Pascal's calculator also known as the arithmetic machine or mechanical calculator invented by Blaise Pascal in the early 17th century. Pascal develop a calculator by the laborious arithmetical calculations required by his father's work as supervisor of taxes in Rouen. This machine to add and subtract two numbers directly and to perform division and multiplication division through repeated addition or subtraction.

The step reckoner or stepped reckoner was a digital mechanical calculator invented by the German around 1672 and completed in 1694.His developed by philosopher Gottfried Wilhelm Leibnitz. It was the first calculator that could perform all four arithmetic operations like addition,substraction,multiplication and division.

A difference engine, first created by Charles Babbage invented by the 1820s, is an automatic mechanical calculator designed to tabulate polynomial functions and could perform simple calculation and It was a steam driven calculating machine designed to solve tables of numbers like logarithm tables.

This calculating machine developed by Charles Babbage in 1830.The Calculating Machine Was a proposed a mechanical general-purpose of computer designed by English mathematician and computer pioneer Charles Babbage in 1830. The Charles Babbage is one of the most successful achievements of Analytical Engine.

Analytical Engine is incorporated an arithmetic logical unit, or and integrated memory, control flow in the form of branching and conditional loops, making it the first design for a general-purpose of computer that could be described in modern terms as Turing-complete in Analytical Engine.

This machine was used in the first U.S Census 1890. The tabulating machine was information stored on punched cards. And Tabulating Machine Company which later became IBM in 1924.

It was the first electronic computer invented by the in the United States in 1930. It is a designed by solve differential equations problem by integration, using through wheel-and-disc mechanisms to perform the integration. Differential Analyzer 25 calculations in few minutes

The next major changes in the history of computer device began in 1937. Large number of perform calculation machine was develop a Howard Aiken. Mark I computer was built as a partnership between IBM and Harvard in 1944. It was the first programmable digital computer.