Blaise Pascal, a French philosopher and mathematician, invented the Pascaline. This was a mechanical machine that was supposed to perform addition. However, Pascal did not get the machine to work properly due to manufacturing problems.

Gottfried Wilhelm von Leibniz, a famous mathematician, designed the Stepped Reckoner, a device capable of adding, subtracting, multiplying, dividing, and calculating the square root of numbers. However, the device tended to break down.

Charles Babbage designed the Analytical Engine. The device was intended to perform calculations based on a program stored on punch cards.

Herman Hollerith invented a tabulating machine that could perform calculations by using electricity rather than mechanical gears. This device was used by the U.S. Census Bureau for the Census of 1890.

Alan Turing presented an idea of a "universal machine." His idea suggested that a computer should be able to perform different things by changing its program, rather than its electronic components.

John Atanasoff built the first electronic computer at Iowa State University. This computer, called the Atanasoff-Berry Computer (ABC), used vacuum tubes and stored information by electronically burning holes into sheets of paper. The ABC used the binary system of 1's and 0's that is still used in computers today.

John Mauchly and J. Presper Eckert constructed the Electronic Numerical Integration and Calculator (ENIAC) at the University of Pennsylvania. It occupied 1500 square feet and weighed 30 tons.

Howard Aiken leads IBM and Harvard University to complete the Mark I. The Mark I used mechanical telephone relay switches for storing information, and received data via punch cards. However, the Mark I was more of a calculator than a computer because it could not make decisions about the data it accepted.

John von Neumann created the idea of a CPU (central processing unit). Later, Neumann, along with John Mauchly and J. Presper Eckert, constructed the EDVAC (Electronic Discrete Variable Automatic Computer) and the EDSAC (Electronic Delay Storage Automatic Computer). These machines interpreted instructions by being fed paper tape that contained machine language, which consists of ones and zeros that represent a switch that is on or off, respectively.

William Shockley, John Bardeen, and Walter Brittain of Bell Laboratories invented the first transistor. Transistors replaced the original vacuum tubes of computers. They made computers smaller, less expensive, and up to 10 times faster. Shockley, Bardeen, and Brittain later won the Nobel Prize in physics for their invention.

The U.S. Census Bureau bought the UNIVAC (UNIVersal Automatic Computer). This computer was the third computer to use the stored program concept, and was built by Mauchly and Eckert.

John Backus and a team of researches developed FORTRAN (FORmula TRANslator), a high-level programming language that had English-like commands.

COBOL (COmmon Business Oriented Language) was developed by the Department of Defense to offer a common language to be used on all computers.

IBM came out with the Model 650. It was smaller, but could still meet the needs of businesses and government agencies, and it became quite popular despite its high price.

BASIC (Beginner's All-Purpose Symbolic Instruction Code) was designed by John Kemeny and Thomas Kurtz at Dartmouth University.

Jack Kilby and Robert Noyce (working independently) developed the integrated circuit, also known as a chip.

IBM introduced the Model 360. It was one of the first computers to use integrated circuits. The reduced size and price made the 360 affordable for hospitals and universities.

Marcian Hoff, an engineer at Intel Corporation, created the microprocessor. The microprocessor is the entire CPU on one single chip, and made it possible to build microcomputers that could fit on a desktop.

The first microcomputer, the Altair, was built.

Steve Wozniak and Steven Jobs created the first Apple Computer.

IBM introduced the IBM-PC. The computer was very successful because of its ability to handle word processing, spreadsheet, and accounting software.