This might be a question that we only ask a little. It would be fair to claim that educated people know what a hard drive or a compact disk is. So there is no real need to investigate that subject more. Or is there? Well, it turned out that the era of storing digital data had its roots at the beginning of the 18th century. And the data holder was called a punch card.
The history of punch cards began in the year 1725 when Basile Bouchon decided to automate the textile loom by making it follow a certain pattern without human assistance. The operator should still be present near the machine to operate it but not entirely. A punch card was a piece of paper with some digits. To give the input one should make a hole where the selected digit was. The card was then read by a reader column by column from above to bottom. Due to the very limited volume of data that could be held within one card, there were usually a pretty big amount of cards for one piece of information. Believe it or not but the principle remained the same even in the 20th century. The design of a punch card as well as the digits on it was adjusted according to the purpose. Some of them could store a binary code like 01001000 01100101 01101100 01101100 01101111 00100001 which says “hello”. Some others were readable for humans and used mostly in offices and archives to store demographic data. And the interesting fact is that punch cards were used by the USA at the end of the 19th century to conduct the 1890 US census.
Another interesting case was the usage of punchcards for the SAGE air defence system that was expected to protect US citizens from a nuclear attack during the Cold War. The whole programme was stored in punch cards. The amount of data was only 5 MB while the number of cards reached 62,500. This created a very serious threat – the possibility of losing some or changing the right order. And of course, it was just not reliable to use paper cards as a key element of the national security system.
The usage of punch cards started declining in the second part of the 20th century as new solutions came on the market. However, it is quite interesting that even I took the last high school exam by marking my answers in black so the machine could read them. Same method, but a new technology.
Reference:
- https://www.computerhope.com/jargon/p/punccard.htm#:~:text=As%20the%20card%20is%20inserted,written%20to%20a%20computers%20memory.
- https://en.wikipedia.org/wiki/1890_United_States_census
- https://www.redhat.com/en/topics/data-storage