The one, the only, the Punching Card

It is incredible that a paper with punched holes would be the main method of storing information for a century, right until the 80s where personalized computers would make digital information storage possible.

The punch card dates back all the way to the late 1700s, when industrialization was in its infancy and people sought to quicken production of goods, which at the time was done by manual labor. Punched cards were used by Basile Bouchon to “code” looms to weave patterns, and was considered to be the firs industrial application of a semi-automated machine. About a hundred years later, the 28 year old Herman Hollerith watched a conductor punch holes in a ticket and was struck with inspiration: the conductor punched the ticket differently according to the person’s traits, so that other conductors would get a heads up if someone was trying to pull a fast one. This gave him the idea that punched cards could store personal information. He created the electromechanical punch-card reader that was used by the Federal Government to record information in the 1890 U.S. census. Hollerith created the Computing-Tabulating-Recording company (CTR) and opened up it’s services to private corporations. The CTR was a huge success. By the middle of the 20th century, punching cards stored nearly all of the world’s data, and the CTR was renamed into International Business Computers, or IBM.


But how was data stored on punching cards? The typical punch card had 12 rows and 80 columns. The top three rows were called “zone” rows: two blank rows at the top, and a row of zeros underneath. Below the zone rows were the number rows, numbered from 1 down to 9. Each row consisted of 80 repeats of the character, hence 80 columns (this 80 column limit influenced our modern coding languages where where there is an 80 character limit in a line!). The top of the card was called the 12 edge (top zone row was the 12th row) and the bottom edge was called the 9 edge (because the bottom row was a row of repeating 9s). In order to type information, an IBM machine was needed: for example, the IBM 029, released in ‘64 as part of IBM’s System/360 rollout. The machine took up an entire table: in fact, it was the table, fused with the machine. Cards traveled on a U shaped belt, shifting over when a key was pressed, like on a typewriter. On the punch card, digits were represented by 1 punch in the appropriate row. Letters were represented by a punch in the 12th or 11th row, and up to 2 holes in the number rows: for example, the letter A would have had a hole in the 12th row, and another hole in the 1 row. The IBM 029 also typed the corresponding character above the punched row.

The stack of punched cards could then be transferred to a computer to code it, or to print the typed information. The computer would read holes by a series of brushes that would brush over the card and detect holes (the computer couldn’t read the printed letters on the card, that was just for human convenience).

This process overall was loud, tedious, and not very efficient. Imagine what would happen if you made a spelling mistake! You’d have to retype the entire card (there was a system of automatic card copying, but still… you get my point). Stacks upon stacks of cards were used to record information… it would be unfortunate if someone, say, dropped a box of them while carrying them to the computer (such events were a perennial hazard). Yet until the 1980s and the technological revolution, most of the western world operated by typing all of their information on punch cards: from conducting world censuses to tracking people of Jewish decent in the holocaust, the punch card undoubtedly played a huge role in shaping our modern world.

Sources:

https://allthatsinteresting.com/ibm-nazis-ww2

https://twobithistory.org/2018/06/23/ibm-029-card-punch.html

https://www.ibm.com/ibm/history/exhibits/vintage/vintage_4506VV2139.html

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