Before hard drives, flash drives, floppy disks, or even magnetic tape became common, computers often used something that looked like this: a punched card.
This is usually called a Hollerith punch card, named after Herman Hollerith, who developed punched-card tabulating equipment in the late 1800s. His system was famously used for the 1890 U.S. Census, helping process census data much faster than manual counting methods.
IBM later became closely associated with punched-card technology, and the standard IBM-style card became one of the most recognizable data storage formats in computing history.
At first glance, this just looks like a stiff piece of paper. But to an early data-processing machine, this was a record. Each column represented one character or value, and the holes represented data.
The classic IBM card had 80 columns and 12 possible punch positions in each column. Those rows were labeled 12, 11, 0, and then 1 through 9. Different combinations of holes represented numbers, letters, and special characters
One side effect of punching holes in cards was something called chad.
Chad is the little piece of paper that gets punched out when a hole is made in the card. If you have ever used a three-hole punch or a paper ticket punch, you have seen the same basic thing. The hole stays in the card, and the tiny paper dot that falls out is the chad.
On a card punch machine, all of that chad would collect in a tray or box inside the machine. It was basically paper confetti made from data processing.
That brings me to a story from my Air Force days.”
Back in the late 1980s, when I was in the U.S. Air Force
working in a Communications Center, we used to have a little fun with the new
people.
We would tell them they had to empty the chad box from the
card punch machine, then separate the classified chad from the unclassified
chad.
Of course, that was completely ridiculous. It was just tiny
bits of paper.
But we would make it sound official. Depending on the day of
the week, or whatever random rule we made up, we would tell them that
odd-numbered punch holes were classified, or even-numbered punch holes were
classified.
Then we would hand them a magnifying glass and a pair of
tweezers and let them start sorting.
Eventually, the boss would find out, come over, and yell at
us for wasting time.
It was hilarious every single time.
But as silly as that story is, it also points to something
important about punched-card systems: the data was physical. The holes were
real, the card stock mattered, and even the little paper pieces punched out of
the card had to go somewhere.
That is very different from the way we think about data
today. Today, data feels invisible because it lives in files, databases,
memory, or the cloud. With punched cards, the data was right there in your
hand.
If the card was bent, torn, mispunched, or jammed in the
reader, the machine might not process it correctly. When that happened, we
usually had to re-punch the card, because the machine needed a clean, readable
physical record to work from.
That physical relationship between the card, the
holes, and the machine is part of what made punched cards so important in early
computing and data processing.
What made punched cards so useful was that they allowed
information to be stored, sorted, counted, and processed mechanically or
electromechanically.
Businesses, governments, universities, and early computer
centers used them for payroll, inventory, accounting, census work, scientific
computing, and software input.
If you have ever heard the phrase ‘do not fold,
spindle, or mutilate,’ this is the kind of technology that phrase came from. If
the card was bent, damaged, or punched incorrectly, the machine could misread
it or reject it.So, in modern terms, a Hollerith card was an early form of
data storage. It was paper, but it was also code. Each hole mattered. Each
column had meaning. And for decades, this was one of the main ways people
talked to computers.
So the next time you see one of these old punch cards,
remember: this little piece of paper was once a database record, a program
line, a payroll entry, a census response, or even part of a computer job.
And somewhere, probably in a long-forgotten
Communications Center, some poor new guy may still be looking for the
classified chad.
References
IBM. (n.d.). The IBM punched card. https://www.ibm.com/history/punched-card
National Bureau of Standards. (1980). Hollerith punched
card code: FIPS PUB 14-1. U.S. Department of Commerce. https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub14-1-May1980.pdf
