The report in the 'New York Times' on February 15, 1946 sounded like a sensation: a "top secret of World War II" was revealed, "an amazing machine that for the first time applies electronic speeds to mathematical problems that were previously too difficult and too cumbersome to solve". 24 weeks after the surrender of the German Wehrmacht, the article revealed the existence of the world's first freely programmable electronic computer.

T.R. Kennedy Jr., the newspaper's technology reporter, had learned from the two scientists John von Neumann and Vladimir Zworykin about the almost unlimited possibilities of the 'Electrical Numerical Integrator And Calculator', or ENIAC for short, which had been kept top secret until then. However, two other US scientists can lay claim to the intellectual paternity of the ENIAC: physicist John William Mauchly and engineer John Presper Eckert.

They wanted to use the computer - as the name 'Numerical Integrator' suggests - to speed up "numerical integration", i.e. the calculation of an area under a curve in the coordinate system. This was not an abstract mathematical exercise. Rather, it was intended to help US Army soldiers in the Second World War to quickly calculate the trajectories of artillery shells.

First version ENIAC I weighed 27 tons

Before the invention of the ENIAC, these so-called shot charts were laboriously calculated using desktop calculators or, somewhat faster, analog computers. In 1942, Mauchly proposed to the army a digital electronic instrument suitable for this task, and a year later construction began at the University of Pennsylvania. The project was top secret and cost 487,000 dollars.

However, the US Army was unable to benefit from the ENIAC during the Second World War, as the machine was not completed until after the end of the war. With the Cold War looming, the purpose of the computing monster changed: The ENIAC was used by US scientists at Los Alamos to calculate the destructive power of the first hydrogen bomb.

The first version, the ENIAC I, consisted of 40 wired electronic racks, three roller cabinets with rotary switches and devices for reading in and outputting IBM punched cards. The computing giant contained around 17,500 tubes, 7,200 diodes and 1,500 relays. Together they weighed 27 tons.

The first computer - Zuse's Z3, ENIAC I or Atanasoff-Berry computer?

Compared to its mechanical predecessors, ENIAC processed its computing steps much faster. The giant machine was able to perform around 5,000 arithmetic operations per second, around 1,000 times faster than mechanical computers.

The history of ENIAC I is also an example of the key role played by women in the early days of computer science. Even before the use of large computers, it was often female mathematicians who did the computing work in the military with pen and paper. In ENIAC I, the complicated program changes were carried out by six female scientists. For a long time, they had to defend themselves against the cliché of "Refrigerator Ladies". This is how the young women were referred to in advertising photos, posing in front of refrigerators to make the machine look good. Today, no one questions the historic achievement of the ENIAC women.

The first programmable mainframe computer

Technology historians are still debating whether the ENIAC I was really the "first computer". In Germany, this title is often attributed to Konrad Zuse's Z3 (1941), the first functioning digital computer in the world. However, the Z3 worked with electromagnetic relay technology, not with tubes. Other experts consider the Atanasoff-Berry computer (1937-1941) to be ahead in the historical race. However, the "ABC" was not a computer in the modern sense, as it was not freely programmable.

"Who invented it? The question is not easy to answer in the case of the computer," says Jochen Viehoff, Managing Director of the Heinz Nixdorf Museum Forum (HNF) in Paderborn. What is certain, however, is that in 1946, the ENIAC was presented as the first programmable mainframe computer in the world that worked exclusively with fast electron tubes.

The ENIAC I also worked quite reliably for important scientific and military computing tasks in tough continuous use, says Viehoff. "It was not unusual for ENIAC to work on a problem for hours or days." However, there was no program memory as we know it from today's computers.

Experience the ENIAC

The ENIAC I was still in operation until 1955. It was then dismantled and the individual parts (racks) were distributed to various institutions. Several ENIAC racks can be found in the American History Museum of the Smithsonian Institute in Washington. But you don't have to fly to the USA to admire parts of the ENIAC I. "We are very pleased to be able to show a total of three original panels from this important milestone in computer history on loan from the USA in the permanent exhibition of the Heinz Nixdorf Museum Forum," says Managing Director Viehoff. With an interactive ENIAC accumulator, visitors can perform simple mathematical calculations themselves - almost like in 1946.