7AK7

The 7AK7 is a pentode vacuum tube. According to its manufacturer, Sylvania, it was "designed for service in electronic computers".
The tube was developed in 1948, designed at the request of L. D. Wilson for use in the Whirlwind computer.
Significant attention was directed towards its manufacturing process in order to ensure the part's
reliability. Dubbed the "computer tube", it became a popular tube for computers for a while. IBM, however, switched to more compact miniature tubes, starting with the IBM 604 in 1948.