Changing ENIAC's vacuum tubes, c. 1940s.

Fullsize image: https://diqn32j8nouaz.cloudfront.net...e_fullsize.jpg



Previously:

Bombe code-breaking machine - GIF
Babbage difference engine - photo
4.5 megabytes of data represented by punch cards - photo
Z1 mechanical computer replica - photo
Cray-1 supercomputer - photo