Konrad Zuse, a German engineer, completes the first general purpose progammable calculator in 1941. He pioneers the use of binary math and boolean logic in electronic calculation.
Colossus, a British computer used for code-breaking, is operational by December of 1943. ENIAC, or Electronic Numerical Integrator Analyzor and Computer, is developed by the Ballistics Research Laboratory in Maryland to assist in the preparation of firing tables for artillery. It is built at the University of Pennsylvania's Moore School of Electrical Engineering and completed in November 1945.

Bell Telephone Laboratories develops the transistor in 1947.

UNIVAC, the Universal Automatic Computer (pictured below), is developed in 1951. It can store 12,000 digits in random access mercury-delay lines.

EDVAC, for Electronic Discrete Variable Computer, is completed under contract for the Ordinance Department in 1952.

In 1952 G.W. Dummer, a radar expert from the British Royal Radar Establishment, proposes that electronic equipment be manufactured as a solid block with no connecting wires. The prototype he builds doesn't work and he receives little support for his research.

Texas Instruments and Fairchild semiconductor both announce the integrated circuit in 1959.

The IBM 360 is introduced in April of 1964 and quickly becomes the standard institutional mainframe computer. By the mid-80s the 360 and its descendents will have generated more than $100 billion in revenue for IBM.