What do you mean by the word "punch card"? Someone has cardboard signs in front of their eyes with numerical combinations applied to them. Someone has special patterns for a machine pattern. Someone will remember the school with the assignments printed on such cards. And these are all true associations. In the article we will analyze in detail what a punch card is, where this invention was previously used and is now used.
Definition
Let's start with the general term. What is a punch card? She is a perforated or perforated card. The word comes from lat. perforo, which means “punch”, and lat. charta - "paper" or "papyrus leaf".
What is a punch card? A data carrier made of thin cardboard, representing data by the absence or presence of punch holes at certain positions on the plate.
The time of the widest distribution of such performance cards was in the second part of the 20th century. Then these cardboard plates were used for input and subsequent storage of data in various automated information processing systems.
What is a punch card today? One of the objects, which is a symbol of the past. In its main meaning, punched cards (like punched tapes) are no longer used. They were supplanted by more convenient, faster and more compact media - semiconductor, optical and magnetic.
First use of cards
The very first punch cards did not appear in the information environment at all. They were associated with the field of weaving. These are the so-called Jacquard punch cards. The element had one purpose - to control the pattern on the Jacquard looms. Punched cards were first used here in 1808.
The jacquard loom is a truly unique invention for its time. This is an automated device that helps to make a large decorative (jacquard) pattern on carpets, fabrics, tablecloths and so on. The device was named after its inventor - the Frenchman Joseph Marie Jacquard.
Jacquard machine
The main components of the machine are knives, frame board, needles, hooks, frame cords and frame house, as well as a punched card with a pattern. Each of the listed elements performed its own function:
- The threads are connected to the machine through arcade cords, which are evenly distributed over the entire width of the machine.
- Knives (fixed in a knife frame) make reciprocating movements in a vertical plane.
- Hooks (located in the area of action of the knives) are captured by knives and raised by them up. Brought out of the area of action of the knives, are lowered together with the frame board.
- The weight of gravity lowers both hooks and warp threads.
- The perforating prism makes rocking and rotational movements. She drives needles in a car.
- Cardboard is put on the perforating prism. This is the punch card. It consists of several paper attachments with non-punched and notched holes. Encountering a cut-out place on the punched card on its way, the needle enters the prism, which allows the hook to remain in the area of the knife. The uncut area on the punch card moves the needle and releases the hook from the knife's coverage area.
How do punch cards work here? The combination of cut and uncut sections on such cards allows the master to determine the desired alternation of raising and lowering the base needle. And this already helps to form a certain pattern on the fabric.
Using punch cards in weaving today
Punch cards remain popular today. Just like the jacquard pattern. It is also used for automated weaving devices. Of course, they are more productive, miniature and compact than the first jacquard machine.
But the principle of using punch cards remains almost the same. The craftswoman finds a card with an interesting pattern for her (or punches a pattern on a clean card on her own), inserts it into the car. The device knits the image on the fabric, according to the cut and not cut places on the plate.
Application in computer science
Despite the fact that punch cards appeared due to weaving, where they are still popular today, they owe their fame to the information environment. Here they were applied for the first time in the "analytical machine" developed by Babbage. It is also known that cards were used for the "intellectual machine" by Semen Nikolaevich Korsakov. This inventor is called the pioneer of the use of punch cards in computer science (1832). Cards were used in mechanized machines for classification of records and information retrieval.
There is evidence that at the end of the 19th century it was punch cards that were used to process census results in the United States.
Punch card format
At the same time, there was no single format of cards. But the "IBM format" introduced in 1928 was considered the most popular. He had such characteristics:
- The arrangement of printed information in 12 lines by 80 columns.
- Size - 187x82 mm, thickness - 0.17 mm.
- Initially, the corners of the cardboard were sharp, and since 1964 - rounded. In the USSR, the innovation did not take root - here they continued to use cards with non-rounded corners.
As for the information volume, then, according to rough estimates, a gigabyte of information encrypted on punch cards could weigh 22 tons. And this is not counting the weight that is lost during punching holes.
In the twentieth century, a wide range of equipment was produced, one way or another, supporting this media. This included various devices for data input / output, information preparation, decryption, collating machines and so on.
Application in computer technology
The main data carrier for first-generation computers (1920-1950) was precisely punch cards. They were used to process and store data.
In the 70-80s, cards began to be used only for data storage. Already in those years they began to be replaced by magnetic tapes. Currently, they are practically not applicable anywhere (except for rare obsolete systems).
But punch cards still left their mark on computer technology. So, the textual video mode of the display, which is displayed by default, contains exactly 80 familiarity horizontally. And, as we recall, there were as many on the punched card.
The main advantage of such storage media at one time was the convenience of data manipulation. Cards could be added, deleted, replaced with others. That is, in fact, the same way to work with information, as in modern text editors.
A curious fact: in 2011, the United States still operated Cardamation, which produced not only punch cards, but also devices for working with them. The latest information on the use of punch cards in modern companies dates back to 2012.
Binary mode
When working in binary mode, the card was considered as a bit two-dimensional array. Therefore, any combination of punches was allowed.
In the well-known IBM 701 system, the machine word occupied 32 bits. When recording information on a punch card, two such machine words were placed on one line. In total, 24 words could be recorded on the medium.
Text mode
When working with a card in text mode, the principle of its use was somewhat different. One column denotes one character. Therefore, the card contained 80 characters. In this case, only certain combinations of punching were allowed.
The numbers were most simply encoded here. This is a breakdown of the position on the card where this figure was displayed. Letters and other characters were encoded in several punctures per character. The absence of any punching meant only a gap.
The IBM / 360 system, for example, determined piercing values for all 256 values of one byte at once. That is, in text mode, you could also enter binary data here.
To make it easier for a person to work with textual information on a perforated card, characters were printed along its edge in the usual form that was readable to us.
Student and exam cards
But what is, for example, punched card category SDA category B? Does this somehow relate to the concept being understood? In fact, these are ordinary examination cards with any examination tasks printed on them. The table with the answer options, on which the examiner must mark, “punch” (perforate) is correct. This explains the name of the examination card.
In schools you can also find punch cards in the Russian language, mathematics and other subjects. These are cards with independent tasks that the student needs to complete. This name was chosen because the card has holes. For example, in place of a letter in a word. In such a hole, the student must write a missing character.
Punched cards in educational institutions are also used for creative tasks. At the place of the pass, the holes need to be depicted, drawn, circled.
A punched card is a very broad concept, better known in the information sphere, computer technology, where such cards were used as information carriers. But punch cards are also used in weaving - both in the past and now. This is also an option for presenting student, examination tasks - cards with holes that need to be filled in a certain way.