5 MB of Data on 62,500 Punched Cards

Programmer standing beside punched cards

“Programmer standing beside punched cards” “This stack of 62,500 punched cards — 5 MB worth — held the control program for the giant SAGE military computer network.” ca. 1955 (via the Computer History Museum)

Explaining data storage in a visual way has always been difficult, but especially so with the transition to magnetic tape in the 1950s and 1960s.

Photographs of punched cards help show the enormity of the task at hand, and also the materiality of the information.

5 megabytes of data seems pretty insignificant nowadays, when terabyte hard drives are a common feature in personal computers.

1 TB = 1,000,000 MB (now that would be a lot of punched cards!)

From the Computer History Museum’s online exhibit on Memory and Storage.

(Originally published on my old site, "The Digital Imaginary" [imaginary.digital], on March 5th, 2015 -- revised and republished April 2nd, 2025.)