In The spirit of modernism in the computer world, I wrote about a card that was used before to store information (mainly programs). Below, the actual card:
Depending on which number is removed in a column, different letters can be obtained. These letters are also printed at the top, so that it is easier to read the information. These cards were later combined in a pile, in order to produce a program. The corner is removed in order to be able to identify if it is misplaced easily.