punch cards
5 MB of Data on 62,500 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.
(Revised and republished April 2nd, 2025)
Punch Card Jam Needs Some Force
In 2010, representatives from the Computer History Museum visited a company in Texas still using an IBM 402 mainframe for everyday accounting jobs: http://ibm–1401.info/402.html
“Jam needs SOME force”
“Card Jam Front View”
The article below mentions the CHM trip to Texas, and a few other old computers still in use:
If It Ain’t Broke, Don’t Fix It: Ancient Computers in Use Today, by Benj Edwards at PCWorld, 2012 (Internet Archive: Wayback Machine)
The biggest problem with maintaining such ancient computer systems is that the original technicians who knew how to configure and maintain them have long since retired or passed away, so no one is left with the knowledge required to fix them if they break.
(Revised and republished April 2nd, 2025)