In the second half of the second millennium, there had been efforts to invent more complicated devices which can be used more comprehensively. The son of a tax officer, Blaise Pascal, was one of pioneers in this direction and he designed a mechanical calculator in 1642 to relax his fathers intensive business life. In 1671, Gottfried Wilhelm von Leibniz invented a computer that was built in 1694. It could add, and, after changing some things around, multiply. The prototypes made by Pascal and Leibniz were not used in many places, and considered weird until a little more than a century later, when Thomas of Colmar created the first successful mechanical calculator that could add, subtract, multiply, and divide. While Thomas of Colmar was developing the desktop calculator, a series of very interesting developments in computers was started in Cambridge, England, by Charles Babbage, a mathematics professor. He began to design an automatic mechanical calculating machine, which he called a difference engine. By 1822, he had a working model to demonstrate with. With financial help from the British government, Babbage started fabrication of a difference engine in 1823. It was intended to be steam powered and fully automatic, including the printing of the resulting tables, and commanded by a fixed instruction program. The mechanical device inventions continued and resulted in the birth of famous company IBM (International Business Machines)

The start of World War II produced a large need for computer capacity, especially for the military. New weapons were made for which trajectory tables and other essential data were needed. In 1942, John P. Eckert, John W. Mauchly, and their associates at the Moore school of Electrical Engineering of University of Pennsylvania decided to build a high - speed electronic computer to do the job. This machine became known as ENIAC (Electrical Numerical Integrator And Calculator)

Transistor is a semiconductor material involving devices amplifying a signal or opens or closes circuit. It is invented in 1947 at Bells lab and have become the key ingredient of the digital circuit. Before the invention of the transistor, digital circuits were composed of vacuum tubes. They had many disadvantages such that they were large in size, required more energy, dissipated more heat and they were more prone to the failure.

Integrated circuit is another name of chip. It is a small electronic device which is made out of a semiconductor material. Its first version was developed in the 1950s Jack Kilby of Texas Instruments and Robert Noyce of Fairchild semiconductor.

Mouse is invented by Douglas Engelbart Of Stanford Research Center in 1963.

Many companies, such as Apple Computer and Radio Shack, introduced very successful PC’s in the 1970s, encouraged in part by a fad in computer (video) games. In the 1980s some friction occurred in the crowded PC field, with Apple and IBM keeping strong. In the manufacturing of semiconductor chips, the Intel and Motorola Corporations were very competitive into the 1980s, although Japanese firms were making strong economic advances, especially in the area of memory chips.