The punched card | IBM (original) (raw)

Punched cards, also known as punch cards, dated to the late 18th and early 19th centuries when they were used to “program” cloth-making machinery and looms. In the late 1880s, inventor Herman Hollerith, who was inspired by train conductors using holes punched in different positions on a railway ticket to record traveler details, invented the recording of data on a machine-readable punched card. Hollerith’s cards were used for the 1890 US Census, which finished months ahead of schedule and under budget. Punched cards emerged as a core product of what would become IBM more than two decades later.

IBM introduced the “IBM Computer Card” in 1928 as the result of a secretive competition between the company’s two top research teams. Over the following three decades, IBM and its rivals redesigned the cards using different sizes and greater numbers of holes with each representing a bit of data. Around 1900, punched cards featured 22 columns and eight punch positions; then 24 columns and 10 positions; until the late 1920s, they had 45 columns of round holes and 12 punch positions.

Data was assigned to the card by punching holes, each one representing a character, in each column. When writing a program, one card represented a line of code — about 80 bytes in total — so large stacks of the cards were required. To load the program or read punched card data, each card would be inserted into a punched card reader to input data into a tabulating machine.

As demand for storage continued to grow, the card soon ran out of room and couldn’t get any larger. To solve this problem, Thomas J. Watson Sr., head of IBM at the time, asked two of his top inventors, Clair D. Lake and J. Royden Pierce, to each develop a new card that held more data. They were instructed to work independently, and only one design would be chosen.

Pierce wanted to use IBM’s existing card with round holes, but make it possible for each hole to represent more than one number or symbol — thereby doubling storage capacity, with half devoted to alphanumeric characters. Lake’s team proposed a card with smaller rectangular holes, which would be easier to read by tabulators. This idea, however, would require new punchers and readers.

Watson asked James W. Bryce, IBM’s most prolific inventor, to choose the best solution. Bryce voted for Lake’s approach because it could be implemented quickly and required the least adjustment in how tabulating machines worked. There were business advantages as well — Lake’s card would double the amount of data stored and be compatible only with IBM-manufactured machines. Introduced in 1928, the new IBM card had 80 columns and 10 rows for coding numbers, then 12 in a modified version of the card unveiled in 1930.