Ken ShirriffThe Computer History Museum has a presentation tonight on the history of computer dating: "Algorithms of Love". I made a special punch card for the event. It wasn't easy to make this card so I'll explain how I did it...
To make the heart, I had to figure out the right sequence of characters to form the hole pattern. Inconveniently, some holes don't form valid characters, so I had to "multi-punch" in some columns. This worked for one card, but the keypunch can't duplicate multi-punched cards.
To duplicate the heart cards, I toggled a short program into the 1401 computer to read a card and print out copies. The 1401 has a special feature called "column binary" that allows it to read and punch cards even if the hole pattern isn't valid.
Michael Ormsby@kenshirriff The THINK placard is a nice touch. I used to work for IBM in the 1980s and I’d see them in the hallways.