ENIAC

ENIAC was finished in 1945 and shown to the public in 1946. It used about 18,000 vacuum tubes and weighed around 30 tons.

Context

ENIAC, short for Electronic Numerical Integrator and Computer, was built at the University of Pennsylvania by J. Presper Eckert and John Mauchly for the US Army, mainly to calculate artillery firing tables. Work began during the Second World War, and the machine was completed late in 1945.

It was unveiled to the press in February 1946. Instead of storing a program in memory, ENIAC was set up for each task by plugging cables and setting switches, a job often done by a team of women programmers, which could take days. Later changes let it hold instructions in a more modern way.

Calling it the first computer needs care. Earlier machines such as Britain's Colossus were electronic and used for codebreaking, but they were built for one purpose. ENIAC is usually described as the first electronic computer that could be reprogrammed to solve a wide range of problems, which is why the wording is general-purpose. Different sources quote slightly different counts for its tubes, weight and speed. The machine filled a large room at the university, and its first well-known job was a calculation connected with the design of nuclear weapons, reportedly run before the public unveiling.