Punch Card Computers: a Thing of the Past?
Learn how we still use them today!
Computers are a pretty new invention. Or at least the modern computer is a new invention. Computers, devices meant to carry out arithmetic or logical operations, have been around for almost 5,000 years. If you’ve ever seen an abacus, that’s a computer! The first programmable machines, like how modern computers work, were invented in 1804!
That was the Jacquard machine: a loom for weaving fabric that used paper cards with holes punched in them. Instead of an operator hand-setting each weave, the Jacquard machine could do it all by itself based on where the holes in the cards were. If there was a hole, a rod would go through and make the machine do one thing. If there was no hole the rod stayed in place.
An improvement on this early technology was player pianos. The idea of self-playing music had been around for some time. Music boxes spin a spool of pins and those hit one note at a time. But they can’t hold a note. In 1863, a functional piano was built that used paper as a valve. As the roll moved over an open valve, air blew out. An opening played a key or moved a peddle. How long that note was played was determined by how long the hole was.
The thing both the loom and the player piano had in common is the long-term storage of information. That is how punch cards came to be part of computers: they were how information was stored. A lot of these early computers were basically overbuilt calculators. You could enter an equation and it would calculate the answer.
Today if you want to program a computer, there are programs to help you do that. But back in the day, you had to write everything by hand—there were machines that you would type out commands onto punch cards. Those punch cards would then be fed into a computer to run the commands. This is actually how we first put a man on the moon. All the data was put on punch cards and then run through a computer to check it. The funny thing is, a woman named Katherine Johnson would check the computer, and she was often more accurate.
It wasn’t long after the moon landing that computers had advanced to the point where you could input the information directly. But that didn’t stop the punch cards. IBM was still selling the IBM 029 punch card machine up until 1984! Why? Because places were still using them. Just because one piece of technology improves doesn’t mean they all do.
You might have used a version of a punch card. Have you ever taken a scantron test at school? You don’t punch a physical hole through the paper, but you fill in the bubble. Light either reflects or is absorbed by the mark.
Even with all the technology in a modern computer, we are still using a version of the punch card today. Kind of crazy to think that a technology that was invented to make fabric is still being used today to score your test!