Perforated card
The perforated card or simply card is a sheet made of cardboard that contains information in the form of perforations according to a binary code. These were the first means used to enter information and instructions into a computer in the 1960s and 1970s. Punched cards were previously used by Joseph Marie Jacquard in the looms of his invention, from where he moved on to the first electronic computers.. With the same logic, perforated tapes were used.
Currently punched cards have been replaced by magnetic and optical means of entering information. However, many optical storage devices, such as CD-ROMs, are also based on a method similar to that used by punch cards, although of course today's media sizes, access speeds, and capacity do not support compared to the old media.
History
In 1725, a Frenchman, the son of an organ maker, Basile Bouchon, adapted the concept of clockwork used in music boxes to the repetitive task of a loom operated through a perforated tape. This invention will be perfected in 1728 by his assistant, Jean-Baptiste Falcon, who will use a series of perforated cards linked together. In 1745 the French engineer and inventor of mechanical automata, Jacques de Vaucanson, applied his knowledge and created the first automatic loom. Based on these two inventions, in 1801 Joseph Marie Jacquard created a famous punched card mechanical loom. These allowed even the most inexperienced users to create complex designs on a cloth.
The British mathematician Charles Babbage, familiar with the work of calculating machines carried out by Blaise Pascal and Gottfried Leibniz, tried between 1833 and 1842 to build a machine that was programmable to do any type of calculation, not only those referring to the calculation of tables logarithmic or polynomial functions. This was the analytical engine. His project included input devices based on the Jacquard loom punch cards, an arithmetic processor, which calculated numbers, a control unit that determined what task was to be performed, an output mechanism, and a memory where numbers could be stored until they were read. processed. In 1842, the Italian engineer and mathematician Luigi Federico Menabrea wrote Notions on the Analytical Engine of Charles Babbage, a text initially published in French. Ada Lovelace, British mathematician and writer, daughter of Lord Byron, heard of Babbage's efforts and became interested in his machine. He read and translated Menabrea's article into English, and in September 1843 Lovelace published in the magazine Scientific Memoirs, under the title "Sketch of the analytical engine invented by Charles Babbage" his own study on the Analytical Engine, with the translation as an annex. In one of the sections, she describes in detail the operations by which the punched cards would "weave" the cards. a sequence of numbers in the analytical engine. This code is considered the first algorithm specifically designed to be executed by a computer, although it was never tested as the machine was never built.
Herman Hollerith developed the technology for processing punch card data for the 1890 United States Census and founded the Tabulating Machine Company (1895) which was one of three companies that united to form the Tabulating Machine Company. Computing Tabulating Recording Corporation (CTR), later renamed IBM. IBM manufactured and marketed a variety of recording machine units for creating, sorting, and tabulating punch cards, even after expanding into computers in the late 1950s. IBM developed the technology of punch card as a powerful tool for business data processing and produced an extensive line of general purpose recording machine units. By the 1950s, IBM cards and IBM unit recording machines had become indispensable in industry and government. Do not fold, spindle or mutilate is a generalized version of the warning that appeared on some punch cards, which became a catchphrase in the post-Second era. World War (although many people had no idea what spindle meant).
From 1905 to 1955, punched cards were the first medium for data entry, storage, and processing in institutional computing and according to the IBM archives: "By 1937 […] IBM had 32 presses working at Endicott, N.Y., printing, cutting, and stacking 5 to 10 million punch cards each day." Punch cards were even used as legal bills, as well as United States government checks and savings bonds. During the 1960s, punch cards were gradually replaced in the first place by magnetic tape data storage, as better and more capable computers became available. Punched cards were still commonly used for data entry and programming until the mid-1970s, when the combination of lower-cost magnetic disk storage and affordable interactive terminals on cheaper minicomputers made punched cards obsolete for applications as well. this role. However, its influence lives on through many standard conventions and file formats. Terminals that replaced punch cards, for example the IBM 3270, displayed 80 columns of text in text mode, for compatibility with existing software. Some programs still operate with the 80-column text convention, although fewer and fewer, while newer systems employ a graphical user interface with variable-width fonts.
Today, punch cards are mostly obsolete and replaced by other storage methods, except for specialized applications.
Card formats
In the early applications of punch cards, all used specifically designed layouts and their utility was initially unknown. It wasn't until around 1928 that punch cards and machines became "general purpose." The rectangular, circular, or oval bits of paper were called chad (recently, chads) or chips (in IBM jargon). Multi-character data, such as words or large numbers, was kept in adjacent columns of the card, known as fields. The group of cards was called a deck. One of the upper corners of the card was normally cut off, so cards that were not oriented correctly, or cards with different corner cuts, could be easily identified. The cards were commonly printed so that the position of the row and column of a punch could be identified. For some applications, printing could include fields, named and marked with vertical lines, logos, and other procedures.
One of the most commonly printed punch cards was the IBM 5081. What's more, it was so common that other card vendors used the same number (see image at right) and even users knew that number.
Hollerith punch card formats in 1887
The punch card patented by Herman Hollerith on June 8, 1887 and used in the mechanical tabulating machines in the 1890 United States census, was a piece of cardboard about 90 mm by 215 mm, with holes round and 20 columns. This card can be viewed on the Columbia University History of Computing site.
This card was the same size as a US dollar at the time. The suggested reasons for making it this size were as follows:
- Hollerith felt that people would treat them with respect if he made them that size.
- The boxes of this size were already available at cheap prices, designed for banks to save the money.
- Equipment to handle these paper sizes were available to the United States Census Office as a loan from the United States Treasury Department.
But there is no real evidence to prove that any of these suggestions are correct.
Hollerith's 45-column punched cards are illustrated in Comrie's The application of the Hollerith Tabulating Machine to Brown's Tables of the Moon.
UNIVAC 90-character punch card
The Remington-Rand UNIVAC punch card format had 45 columns and round holes, with two sets of 6 punch places in each. The rows of each set were labeled 0, 1/2, 3/4, 5/6, 7/8, and 9.
IBM 80 Column Format Punched Card
This IBM card format, designed in 1928, had rectangular holes, 80 columns with 12 punch locations each, and one character for each column. The card size was exactly 187.325mm by 82.55mm. The cards were made of smooth stock, 0.179 mm wide. There are about 143 cards for every inch of thickness. In 1964, IBM switched from square to rounded corners.
The bottom 10 positions represented (from top to bottom) the digits 0 through 9. The top two positions in a column were called zone perforation 12 (top), and zone 11 perforation. Originally only numeric information was encoded, with one perforation per column, indicating the digit. Signs could be added to a field by overpunching the least significant bit with a zone punch: 12 for addition and 11 for subtraction. Zone perforations also had other uses in processing, such as indicating a master record.
Later, codes for uppercase letters and special characters were introduced. A column with two perforations (zone [12,11,0] + digit [1-9]) was a letter; 3 perforations (zone [12,11,0] + digit [2-4] + 8) was a special character. The introduction of the EBCDIC in 1964 allowed columns with up to 6 perforations (zones [12,11,0,8,9] + digit [1-7]). IBM and other manufacturers used very different encodings for 80-column card characters.
For some computer applications, binary number formats were used, where each hole represented a single binary digit (bit), each column (or row) was treated as a single bit field, and any combination of holes was allowed. For example, IBM's 704/709/7090/7094 series scientific computers treated each row as two 36-bit words, usually in columns 1-72, ignoring the last 8 columns (the 72 columns were selected using a control Panel). Other computers, such as the IBM 1130 or the System/360, used all the columns. To the amusement of the operator or a visitor, in binary mode, the cards could be punched in all their possible punchable positions at once, these are called slot cards.
The 80-column card format dominated the industry, becoming known only as IBM cards, so much so that even other industries had to make cards and equipment to process them.
Mark sense cards
The mark sense (electrographic) cards, developed by Reynold B. Johnson at IBM, had printed ovals that could be marked with a special electrographic pen. The cards could typically be punched with some initial information, such as the name and location of an inventory item. Information to be attached, such as the number of units of the item in stock, could be marked on the ovals. Card punches with an option to detect mark sense cards could then punch the corresponding information on the card.
Opening Cards
Opening cards have a hole sliced into the right side of the punch card. A piece of 35mm microfilm containing a microform image is mounted in the hole. Opening cards are used for engineering diagrams from any engineering discipline. Information about the diagram, for example the drawing number, is typically punched out and printed on the remainder of the card. Aperture cards have some advantages over digital systems for archiving information.
IBM 51-column punch card
This IBM punch card format was a shortened 80-column card. Shortening was sometimes done by cutting and removing, at the time of punching, a piece of an 80-column card. These cards were used in some retail and inventory applications.
IBM Portable Punch
According to IBM archives, "The IBM Supply Division introduced the Port-A-Punch in 1958 as a fast and accurate means of punching holes in specially graded IBM cards.". Designed to fit in a pocket, the portable hole punch made it possible to create punch card documents anywhere.” The product was conceived for "in focus" —such as physical inventories, job tickets, and statistical surveys—as it eliminated the need for prior writing or writing of source documents. Unfortunately, the resulting holes were "hairy" and sometimes caused problems with the equipment used to read the cards.
Contenido relacionado
William Bradford Shockley
EXPTIME
Windows Me