In the early days of computer cartography, translating information into languages that a computer could understand typically required punching physical holes into punched cards:
Cartographers used coding pads like the blue-green and white one shown to the left to draft their code, often in a language called FORTRAN, which was short for “Formula Translation.” After handwriting their code on the numbered columns of these pads, cartographers would have someone else transfer it into individual punched cards like the one above—a labor-intensive job, given that a single project could yield hundreds of thousands of punched cards. For example, the Chicago Area Transportation Study referenced in the section on Calculating Routes" required 378,000 punched cards.