Herman Hollerith and Punch Cards

Hollerith is a name that you'll come across if you study computer science. Several concepts have been named after Herman Hollerith who invented an automated punch card tabulating machine.

Herman Hollerith was one of the founders of a company that later became IBM. Hollerith's invention lead to the punched cards which were a big part of the day to day work of early professional computer programmers.

Herman Hollerith was born on February 29th 1860 in Buffalo, New York. Yes, he had a leap day birthday, so we thought we'd better cover him today or we would have to wait another 4 years!

We think it's important that kids understand the history of computing. Most western kids today grow up with internet at home and access to mobile technology. We've previously written about key tech innovators such as Ada Lovelace, George Boole, Grace Hopper and Thomas Edison.

Hollerith originally invented his punch card machine for accurate data handling for the US census. (There had been punched cards before in use in weaving looms and musical instruments.)

IBM progressed the use of punch card based machines and early general purpose computers were programmed with punch cards.

Thanks to Hollerith, early computer programmers were able to capture their programs on physical punched cards that could be fed into a computer. This meant that programs could be prepared in advance and modified by adding, removing or physically editting cards.

Punch Card

Early computer programmers didn't have the benefit of being able to run their code immediately. They would have to write the whole thing and then submit it when they got a slot on a computer.  It was very annoying if it had a bug.

Throughout my career I met lots of people who had used punched cards in their job. The legacy of punched cards was very strong in the layout of the FORTRAN programming language that I used in one of my early jobs.

If you want to see a punch card preparation machine then watch Bubble Whiting's fantastic demonstration and explanation of how she used one in her job:

In this video Professor Brailsford explains how punch cards, or Hollerith cards, work and shares his experience of using them:

In these days of fantastic browser based coding sites for kids, Hollerith cards look really hard work! But they were a significant step towards coding becoming accessible.