The MIT Whirlwind, like Stretch, was a military machine. Specifically, Whirlwind was designed to be a flight simulator to train bomber crews. A beast of a machine, Whirlwind contained 4,500 vacuum tubes and ate up 3,100 square feet of floor space.

Completed in 1948, Whirlwind was the first computer to use magnetic core memory, the earliest ancestor to the RAM in our computers today. Magnetic core memory could store a state of magnetization indefinitely and discharge the data represented by states of magnetization instantaneously. Instantaneous access to data is a requirement in a flight sim, because the computer needs to react to trainees' decisions in real time.

Sadly, Whirlwind was never used as a flight simulator, but thanks to the new technologies it incorporated it represents an important advance in the history of computing.