Funny and nerdy comic over at xkcd. I got reminded of my first programming at ETH back in the day, actually using punch cards. Each card represented one line of code. The punching machines were quite hefty apparatuses, with all the necessary mechanics to fetch new blank cards, and then route the finished card onto a stack. Then you handed the stack over to the computer operator, who inserted it into a reader to run the program on a CDC mainframe computer, and you received back your card stack with a printout. After 15 minutes if you were lucky.
Inserting a line of code meant adding a card to the stack. Correcting a mistake meant retyping the whole card, so you were always trying to find an balance between line length and stack height. At times, you got back your printout indicating a “Hollerith Error”, meaning there was a problem reading a card.
I still have all these sweaters somewhere in a box. We called them jumpers, though.