Perforated Card: What is it and what is it for? How does it work? – Step by step guide


Have the understanding of the function that obtained the Perforated card It involves knowing the principle of what computing was, through training a machine to store a certain group of data.

This being its function, another of its objectives that prompted its creation was the need to reduce the use of people to perform a specific procedure. Through these principles, it was possible to obtain, process and store information precisely within a short period of time.

The birth of the punch card

His first appearance is still debated to this day. However, the chronological order dates from its invention around the year 1725 as a «large roll of perforated paper» that allowed control a textile loom from a company in France.

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Based on this concept, different groups of engineers were in charge of improving the idea to apply it in their inventions a couple of years later.

birth of the punch card

To this day, it is considered the first CD-ROM that could exist in history, because IBM developed its main operation to achieve this type of storage.

Therefore, punched cards are recognized as a sheet of varied size, whose material is cardboard, which allows a series of perforations in binary code to store a specific type of information.

Herman Hollerith and his tabulating machines

This engineer was one of the founders of what is known today as IBM, which decided to use this type of cardboard to census the population of the United States.

To achieve this, within the sheet a varied number of questions with two answers or probable data were introduced, the right one being the one drilled into her. Once the punched card was obtained, it was placed in a container with mercury that had cables in its upper part.

When any of these cables found a hole inside the sheet, they recorded the information that was provided in the mercury. In this way, punch cards were used to load a specific type of information automatically.

General characteristics

The main concept of the punch card is something that has evolved over the years, because little by little it was improving until it became what it is today. For those dates, these little cardstock sheets they were distinguished from any other by possessing specific characteristics.

Based on the binary method, the type of response that was drilled into itself was organized within a specific column. The number of columns varied according to the size of the card.

Also, these plates were manufactured and distributed for a specific type of machine, so that they work only with it.

How did these punch cards work?

As you have read before, each punch card stock was very resistant to the different types of holes that were made in it. These marks varied according to the shape of the pencil, that is, round, rectangular or oval. The IBM company proposed identify them as «chips» or «chads».

Each of these holes was accompanied by «fields», which were nothing more than data with a variability of characters, which mainly contained words or numbers of large quantity. These fields were established in columns close to the card, generally within its borders.

How these punch cards worked

An important aspect of the sheets is that their corners had a specific type of cutout that allowed people to determine the deck to which it belonged. As each machine finished using a punch card, it was saved, destroyed, or discarded to avoid duplication of information.

From this moment on, the knowledge and practical use of the punch card allowed different companies to evolve its principle. Thanks to this, on your computer you have the ability to process and store all kinds of data through magnetic and optical media, which is based on a method similar to that of these sheets used in the 19th century.

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