The document traces the history of personal computers from manually operated abacus in the 12th century to modern electronic computers. It discusses early mechanical counting machines invented by Pascal and Leibniz. In 1890, Herman Hollerith developed the first electromechanical machine using punched cards to tabulate the US Census faster. The first modern electronic computer without mechanical parts, ENIAC, was developed in 1946. Transistors replaced vacuum tubes in the 1950s, integrated circuits were invented in the 1960s, and microprocessors placed computing power in the hands of individuals and small businesses in the 1970s, launching the era of microcomputers.

1. HISTORY OF PERSONAL COMPUTERS