1st Generation Digital Computers
 Soon after the invention of the Mark 1, scientists began to build computers that had almost no moving parts. That is, they were electronic rather than mechanical. The computers that you'll be reading about are called digital computers. A digital computer changes information into digits to be stored and processed.
 

 The computer, called the ENIAC, was even bigger than the Mark 1. It weighed over 30 tons! It conducted electricity through vacuum tubes. In fact, the computer used over 18,000 vacuum tubes!

ENIAC stands for Electronic Numerical Integrator and Calculator.

  As moving parts inside computers were replaced by electrical circuits, computers worked faster and more efficiently. The first all digital computer was completed in 1946 at the University of Pennsylvania under the direction of two engineers, John W. Mauchly and J. Presper Eckert.

 This pull out rack, allowed computer trchnicians to more easily find burt out tubes.

Radios and televisions used vacuum tubes through the 1950s.

 Vacuum tubes get hot, and 18,000 of them created a lot of heat. So, it was necessary for the ENIAC to have special air conditioning units to keep it cooled down.

 

The ENIAC's electric bill was $1,800 a month in 1946!

 The ENIAC was considered quite a "brain." It was 300 times faster than the Mark 1. It worked a thousand times faster than a person using a desk calculator. It was given a problem that would have taken 100 engineers, working eight hours a day, an entire year to solve. The ENIAC solved the problem in two hours.  

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Eniac's massive air conditioning requirements.

Notice the ducts in the ceiling.

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 Here we see two technicians "programing" ENIAC by rewiring the machine.

Stored programs had not yet been invented.