A punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions. Now an obsolete recording medium, punched cards were widely used throughout the 19th century for controlling textile looms and in the late 19th and early 20th century for operating fairground organs and related instruments. They were used through the 20th century in unit record machines for input, processing, and data storage. Early digital computers used punched cards, often prepared using keypunch machines, as the primary medium for input of both computer programs and data. Some voting machines use punched cards.
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Punched cards were first used around 1725 by Basile Bouchon and Jean-Baptiste Falcon as a more robust form of the perforated paper rolls then in use for controlling textile looms in France. This technique was greatly improved by Joseph Marie Jacquard in his Jacquard loom in 1801.
Semen Korsakov was reputedly the first to use the punched cards in informatics for information store and search. Korsakov announced his new method and machines in September 1832, and rather than seeking patents offered the machines for public use.[1]
Charles Babbage proposed the use of "Number Cards", "pierced with certain holes and stand opposite levers connected with a set of figure wheels ... advanced they push in those levers opposite to which there are no holes on the card and thus transfer that number" in his description of the Calculating Engine's Store.[2]
Herman Hollerith invented the recording of data on a medium that could then be read by a machine. Prior uses of machine readable media, such as those above (other than Korsakov), had been for control, not data. "After some initial trials with paper tape, he settled on punched cards...",[3] developing punched card data processing technology for the 1890 US census. He founded the Tabulating Machine Company (1896) which was one of four companies that merged to form Computing Tabulating Recording Corporation (CTR), later renamed IBM. IBM manufactured and marketed a variety of unit record machines for creating, sorting, and tabulating punched cards, even after expanding into electronic computers in the late 1950s. IBM developed punched card technology into a powerful tool for business data-processing and produced an extensive line of general purpose unit record machines. By 1950, the IBM card and IBM unit record machines had become ubiquitous in industry and government. "Do not fold, spindle or mutilate," a generalized version of the warning that appeared on some punched cards (generally on those distributed as paper documents to be later returned for further machine processing, checks for example), became a motto for the post-World War II era (even though many people had no idea what spindle meant). [4]
From the 1900s, into the 1950s, punched cards were the primary medium for data entry, data storage, and processing in institutional computing. According to the IBM Archives: "By 1937... IBM had 32 presses at work in Endicott, N.Y., printing, cutting and stacking five to 10 million punched cards every day."[5] Punched cards were even used as legal documents, such as U.S. Government checks[6] and savings bonds. During the 1960s, the punched card was gradually replaced as the primary means for data storage by magnetic tape, as better, more capable computers became available. Punched cards were still commonly used for data entry and programming until the mid-1980s when the combination of lower cost magnetic disk storage, and affordable interactive terminals on less expensive minicomputers made punched cards obsolete for this role as well.[7] However, their influence lives on through many standard conventions and file formats. The terminals that replaced the punched cards, the IBM 3270 for example, displayed 80 columns of text in text mode, for compatibility with existing software. Some programs still operate on the convention of 80 text columns, although fewer and fewer do as newer systems employ graphical user interfaces with variable-width type fonts.
Today punched cards are mostly obsolete and replaced with other storage methods, except for a few legacy systems and specialized applications.
The terms punched card, punch card, and punchcard were all commonly used, as were IBM card and Hollerith card (after Herman Hollerith). IBM used "IBM card"[8] or, later, "punched card" at first mention in its documentation and thereafter simply "card" or "cards".[9] The term punched card was generally avoided for blank cards, with other terms such as tabulating card used.[10] Specific formats were often indicated by the number of character positions available, e.g. 80-column card.
The early applications of punched cards all used specifically designed card layouts. It wasn't until around 1928 that punched cards and machines were made "general purpose". The rectangular, round, or oval bits of paper punched out are called chad (recently, chads) or chips (in IBM usage). Multi-character data, such as words or large numbers, were stored in adjacent card columns known as fields. A group of cards is called a deck. One upper corner of each card was usually cut so that cards not oriented correctly, or cards with different corner cuts, could be easily identified. Cards commonly had printing such that the row and column position of a hole could be identified. For some applications printing might have included fields, named and marked by vertical lines, logos, and more.[11]
Herman Hollerith was awarded a series of patents[13] in 1889 for mechanical tabulating machines. These patents described both paper tape and rectangular cards as possible recording media. The card shown in U.S. Patent 395,781 of June 8 was preprinted with a template and had holes arranged close to the edges so they could be reached by a railroad conductor's ticket punch, with the center reserved for written descriptions. Hollerith was originally inspired by railroad tickets that let the conductor encode a rough description of the passenger:
Use of the ticket punch proved tiring and error prone, so Hollerith invented a pantograph "keyboard punch" that allowed the entire card area to be used. It also eliminated the need for a printed template on each card, instead a master template was used at the punch; a printed reading board could be placed under a card that was to be read manually. Hollerith envisioned a number of card sizes. In an article he wrote describing his proposed system for tabulating the 1890 U.S. Census, Hollerith suggested a card 3 inches by 5½ inches of Manila stock "would be sufficient to answer all ordinary purposes."[15]
The cards used in the 1890 census had round holes, 12 rows and 24 columns. A reading board for these cards can be seen at the Columbia University Computing History site.[16] At some point, 31⁄4 by 73⁄8 inches (82.550 by 187.325 mm) became the standard card size, a bit larger than the United States one-dollar bill of the time (the dollar was changed to its current size in 1929). The Columbia site says Hollerith took advantage of available boxes designed to transport paper currency.
Hollerith's original system used an ad-hoc coding system for each application, with groups of holes assigned specific meanings, e.g. sex or marital status. Later designs standardized the coding, with twelve rows, where the lower ten rows coded digits 0 through 9. This allowed groups of holes to represent numbers that could be added, instead of simply counting units.
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.[17][18]
This IBM card format, designed in 1928,[19] had rectangular holes, 80 columns with 12 punch locations each, one character to each column. Card size was exactly 7 3⁄8 by 3 1⁄4 inches (187.325 mm × 82.55 mm). The cards were made of smooth stock, 0.007 inches (180 µm) thick. There are about 143 cards to the inch (56/cm). In 1964, IBM changed from square to round corners.[20] They came typically in boxes of 2000 cards[21] or as continuous form cards. Continuous form cards could be both pre-numbered and pre-punched for document control (checks, for example).[22]
The lower ten positions represented (from top to bottom) the digits 0 through 9. The top two positions of a column were called zone punches, 12 (top) and 11. Originally only numeric information was punched, with 1 punch per column indicating the digit. Signs could be added to a field by overpunching the least significant digit with a zone punch: 12 for plus and 11 for minus. Zone punches had other uses in processing as well, such as indicating a master record.
______________________________________________
/&-0123456789ABCDEFGHIJKLMNOPQR/STUVWXYZ
Y / x xxxxxxxxx
X| x xxxxxxxxx
0| x xxxxxxxxx
1| x x x x
2| x x x x
3| x x x x
4| x x x x
5| x x x x
6| x x x x
7| x x x x
8| x x x x
9| x x x x
|________________________________________________
Reference:[23] Note: The Y and X zones were also called the 12 and 11 zones, respectively.
Later, multiple punches were introduced for upper-case letters and special characters.[24] A letter had two punches (zone [12,11,0] + digit [1-9]); most special characters had two or three punches (zone [12,11,0,or none] + digit [2-7] + 8); a few special characters were exceptions (in EBCDIC "&" was 12 only, "-" was 11 only, and "/" was 0 + 1). With these changes, the information represented in a column by a combination of zones [12, 11] and digits [1-9] was dependent on the use of that column. For example the combination "12-1" was the letter "A" in an alphabetic column, a plus signed digit "1" in a signed numeric column, or an unsigned digit "1" in a column where the "12" had some other use. The introduction of EBCDIC in 1964 allowed columns with as many as six punches (zones [12,11,0,8,9] + digit [1-7]). IBM and other manufacturers used many different 80-column card character encodings.[25][26] A 1969 American National Standard defined the punches for 128 characters and was named the Hollerith Punched Card Code (often referred to simply as Hollerith Card Code), honoring Hollerith.[27]
For some computer applications, binary formats were used, where each hole represented a single binary digit (or "bit"), every column (or row) was treated as a simple bitfield, and every combination of holes was permitted. For example, the IBM 711 card reader used with the 704/709/7090/7094 series scientific computers treated every row as two 36-bit words, ignoring 8 columns. (The specific 72 columns used were selectable using a plugboard control panel, which was almost always wired to select columns 1-72.) Sometimes the ignored columns (usually 73–80) were used to contain a sequence number for each card, so the card deck could be sorted to the correct order in case it was dropped. Other computers, such as the IBM 1130 or System/360, used every column. The IBM 1402 could be used in "column binary" mode, which stored two characters in every column, or one 36-bit word in three columns. However, most of the older card punches were not intended to punch more than 3 holes in a column, so they couldn't be used to produce binary cards.
As a prank, in binary mode, cards could be punched where every possible punch position had a hole. Such "lace cards" lacked structural strength, and would frequently buckle and jam inside the machine.
The 80-column card format dominated the industry, becoming known as just IBM cards, even though other companies made cards and equipment to process them.
One of the most common printed punched cards was the IBM 5081, a general purpose layout with no field divisions. Indeed, it was so common that other card vendors used the same number (see image at right) and even users knew its number.
The 80-column card could be scored, on either end, creating a stub that could be torn off, leaving a stub card or short card. A common length for stub cards was 51-columns. Stub cards were used in applications requiring tags, labels, or carbon copies.[22].
According to the IBM Archive: IBM's Supplies Division introduced the Port-A-Punch in 1958 as a fast, accurate means of manually punching holes in specially scored IBM punched cards. Designed to fit in the pocket, Port-A-Punch made it possible to create punched card documents anywhere. The product was intended for "on-the-spot" recording operations—such as physical inventories, job tickets and statistical surveys—because it eliminated the need for preliminary writing or typing of source documents..[29] Unfortunately, the resulting holes were "furry" (i.e. not cleanly cut, owing to the perforations) and sometimes caused problems with the equipment used to read the cards.
In the early 1970s IBM introduced a new, smaller, round-hole, 96-column card format along with the IBM System/3 computer.[30] The IBM 5496 Data Recorder, a keypunch machine with print and verify functions, and the IBM 5486 Card Sorter were made for these 96-column cards.
These cards had tiny (1 mm), circular holes, smaller than those in paper tape. Data was stored in six-bit binary-coded decimal code, with three rows of 32 characters each, or 8-bit EBCDIC. In this format, each column of the top tiers are combined with two punch rows from the bottom tier to form an 8-bit byte, and the middle tier is combined with two more punch rows, so that each card contains 64 bytes of 8-bit-per-byte binary data.[31]
The Powers/Remington Rand card format was initially the same as Hollerith's; 45 columns and round holes. In 1930 Remington-Rand leap-frogged IBM's 1928 introduced 80 column format by coding two characters in each of the 45 columns - producing what is now commonly called the 90-column card.[32] For its character codings, see Centrum Wiskunde & Informatica.[33]
IBM's Fred M. Carroll[34] developed a series of rotary type presses that were used to produce the well-known standard tabulating cards, including a 1921 model that operated at 400 cards per minute (cpm). Later, he developed a completely different press capable of operating at speeds in excess of 800 cpm, and it was introduced in 1936.[5][10] Carroll's high-speed press, containing a printing cylinder, revolutionized the manufacture of punched tabulating cards.[35] It is estimated that between 1930 and 1950, the Carroll press accounted for as much as 25 percent of the company's profits[36]
Discarded printing plates from these card presses, each printing plate the size of an IBM card and formed into a cylinder, often found use as desk pen/pencil holders, and even today are collectible IBM artifacts (every card layout[37] had its own printing plate).
IBM initially required that its customers use only IBM manufactured cards with IBM machines, which were leased, not sold. IBM viewed its business as providing a service and that the cards were part of the machine. In 1932 the government took IBM to court on this issue. IBM fought all the way to the Supreme Court and lost; the court ruling that IBM could only set card specifications. In another case, heard in 1955, IBM signed a consent decree requiring, amongst other things, that IBM would by 1962 have no more than one-half of the punched card manufacturing capacity in the United States. Tom Watson Jr.'s decision to sign this decree, where IBM saw the punched card provisions as the most significant point, completed the transfer of power to him from Thomas Watson, Sr.[36]
While punched cards have not been widely used for a generation, the impact was so great for most of the 20th century that they still appear from time to time in popular culture. For example:
metaphor... symbol of the 'system' — first the registration system and then bureaucratic systems more generally ... a symbol of alienation ... Punched cards were the symbol of information machines, and so they became the symbolic point of attack. Punched cards, used for class registration, were first and foremost a symbol of uniformity. .... A student might feel 'he is one of out of 27,500 IBM cards' ... The president of the Undergraduate Association criticized the University as 'a machine ... IBM pattern of education.'... Robert Blaumer explicated the symbolism: he referred to the 'sense of impersonality... symbolized by the IBM technology.'... ––Steven Lubar[40]
Creation and processing of punched cards was handled by a variety of devices, including:
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This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.