Punched card

A punch card or punched card (or punchcard or Hollerith card or IBM card), is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions. Almost an obsolescent recording medium, punched cards were widely used throughout the nineteenth century for controlling textile looms and through the twentieth century in unit record machines for input, processing, and data storage. Digital computers used punched cards, later scanned by card readers, as the primary medium for input of both computer programs and data, with offline data entry on key punch machines. Some voting machines have used punch cards.

History

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. Herman Hollerith developed punched card data processing technology for the 1890 US census and founded the Tabulating Machine Company (1896) which was one of three 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 computers in the late 1950s. IBM developed punch 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 punch cards, became a motto for the post-World War II era (even though many people had no idea what spindle meant).

From the 1900s, into the 1950s, punch 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." ^[1] Punch cards were even used as legal documents, such as U.S. Government checks and savings bonds. During the 1960s, the punch card was gradually replaced as the primary means for data storage by magnetic tape, as better, more capable computers became available. Punch cards were still commonly used for data entry and programing until the mid-1970s when the combination of lower cost magnetic disk storage, and affordable interactive terminals on less expensive minicomputers made punch cards obsolete for this role as well. However, their influence lives on through many standard conventions and file formats. The terminals that replaced the punched cards displayed 80 columns of text, 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, punch cards are obsolete outside of a few legacy systems and specialized applications.

Card formats

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 a card was usually cut so that cards not orientated correctly, or cards with different corner cuts, could be easily identified. Cards were commonly printed so that the row and column position of a punch could be identified. For some applications printing might have included fields, named and marked by vertical lines, logos, and more.

The most common printed punched card was the IBM 5081. Indeed, it was so common that other card vendors used the same number (see image at right) and even users knew its number.

In addition to punching, printing, and handwriting, there were other methods used to record information on punched cards. Two examples were:

• Mark sense (Electrographic) cards, developed by Reynold B. Johnson, had printed ovals that could be marked with an electrographic pencil. Card punches with an option to detect mark sense cards could then punch the corresponding information into the card.

• Aperture cards used punch cards for storing "blueprints". A drawing was photographed onto 35 mm film and the image mounted in a window on the right half of the punch card. Information about the drawing, e.g. the drawing number, was punched in the left half.

Hollerith's punch card formats

The punched card Herman Hollerith patented on June 8, 1887 and used with mechanical tabulating machines in the 1890 U.S. Census, was a piece of cardboard about 90 mm by 215 mm (the same size as 1887 US paper currency), with round holes and 24 columns. This card can be seen at the Columbia University Computing History site^[2].

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^[3].

UNIVAC 90-character punch card format

This UNIVAC card format had round holes, 45 columns with 12 punch locations each, two characters to each column. For the 90-column card character codings, see Winter, Dik T.. 90-column Punched Card Code. Retrieved on October 2006.

IBM 80 column punch card format

This IBM card format, designed in 1928, ^[4] had rectangular holes, 80 columns with 12 punch locations each, one character to each column. Card size was exactly 7-3/8 inch by 3-1/4 inch (187.325 by 82.55 mm. The cards were made of smooth stock, 0.007 inch (0.178 mm) thick. In 1964, IBM changed from square to round corners. ^[5] There are about 143 cards to the inch, as thickness of the IBM punched card.

The top two positions of a column were called zone punches, 12 (top) and 11. These often encoded plus and minus signs. The lower ten positions represented (from top to bottom) the digits 0 through 9. Originally only numeric information was coded, with 1 or 2 punches per column: digits (digit [0-9]) and signs (zone [12,11] – sometimes overpunching the Least Significant Digit). Later, codes were introduced for upper-case letters and special characters. A column with 2 punches (zone [12,11,0] + digit [1-9]) was a letter; 3 punches (zone [12,11,0] + digit [2-4] + 8) was a special character. The introduction of EBCDIC in 1964 allowed columns with as many as 6 punches (zones [12,11,0,8,9] + digit [1-7]). IBM and other manufacturers used many different 80-column card character codings. ^[6][7]

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 704/709/7090/7094 series scientific computers treated every row as two 36-bit words, usually in columns 1-72, ignoring the last 8 columns (the 72 columns used were selectable using a control panel). Other computers, such as the IBM 1130 or System/360, used every column. For operator and visitor amusement, in binary mode, cards could be punched where every possible punch position had a hole: these were called "lace cards" (such cards lacked structural strength and generally could not be further processed by unit record machines).

For programming language use, use of the full 80 columns was possible in principle, but the language standards of the day normally specified positions 1-72, with columns 73-80 either left blank or used for card sequence numbers, which enabled a deck that had been dropped, or corrupted while being read, to be automatically resequenced. Both Fortran and Cobol designated columns 73-80 for "programmer use" and the compiler specifically ignored anything in those columns.

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.

IBM 51 column punch card format

This IBM card format was a shortened 80-column card; the shortening sometimes accomplished by tearing off, at a perforation, a stub from an 80 column card. These cards were used in some retail and inventory applications.

IBM Port-A-Punch

From 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.^[8]. Unfortunately, the resulting holes were "furry" and often caused problems with the equipment used to read the cards.

IBM Votomatic

From the IBM Archive (1965): In the privacy of the voting booth, the IBM Votomatic was used to register selections on a specially designed punched card ballot.^[9].

Punch cards received considerable notoriety in 2000 when their uneven use in Votomatic style systems in Florida was alleged to have affected the outcome of the U.S. presidential election. Invented by Joseph P. Harris, Votomatic was manufactured under license by IBM. William Rouverol, who built the prototype and wrote patents, stated that after the patents expired in 1982 lower quality machines had appeared on the market. The machines used in Florida had five times as many errors as a true Votomatic, he said.^[10].

Punch-card-based voting systems, the Votomatic system in particular, use special cards where each possible hole is pre-scored, allowing perforations to be made by the voter pressing a stylus through a guide in the voting machine. These pre-perforated cards are called Port-A-Punch cards (above). One notorious problem with this system is the incomplete punch; this can lead to a smaller hole than expected, or to a mere slit in the card, or to a mere dimple in the card, or to a hanging chad. This technical problem was claimed by the Democratic Party to have influenced the 2000 U.S. presidential election in the state of Florida; critics claimed that punch-card voting machines were primarily used in Democratic areas and that hundreds of ballots were not read properly or were disqualified due to incomplete punches, which allegedly tipped the vote in favor of George W. Bush over Al Gore.

Other punch-card voting systems use a metal hole-punch mechanism that does not suffer nearly as much from this fault, although most states have eliminated punch-card voting systems of all types after the 2000 Florida experience.

IBM 96 column punch card format

In the early 1970s IBM introduced a new, smaller, round-hole, 96-column card format along with the IBM System/3 computer. 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, with the two extra holes located in the top rows. For the 96-column card character codings, see Winter, Dik T.. 96-column Punched Card Code. Retrieved on October 2006.

Punched Card Manufacturing

IBM's Fred M. Carroll^[11] 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 completely different press capable of operating at speeds in excess of 800 cpm, and it was introduced in 1936.^[12][1] Carroll's high-speed press, containing a printing cylinder, revolutionized the manufacture of punched tabulating cards.^[13] It is estimated that between 1930 and 1950, the Carroll press accounted for as much as 25 per cent of the company's profits^[14]

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 collectable IBM artifacts (every card layout^[15] 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, 1955, case IBM signed a consent decree requiring, amongst other things, that IBM by 1962 have no more than 1/2 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.^[14]

Transmission Of Punch Card Data

The invention for electrical transmission of punch card data to another location & reproducing other cards was in early 1930s. The device was called an Electrical Remote Control of Office Machines and was assigned to IBM. Inventers were Joseph C.Bolt of Boston & Curt I. Johnson; Worcester, Mass. assors to the Tabulating Machine Co., Endicott, NY. The Distance Control Device received a US patent in Aug.9,1932: pat# 1,870,230. Letters from IBM talk about filling in Canada in 9/15/1931.

Standards

• ANSI INCITS 21-1967 (R2002), Rectangular Holes in Twelve-Row Punched Cards (formerly ANSI X3.21-1967 (R1997)) Specifies the size and location of rectangular holes in twelve-row 3-1/4 inch wide punched cards.
• ANSI X3.11 - 1990 American National Standard Specifications for General Purpose Paper Cards for Information Processing
• ANSI X3.26 - 1980/R1991) Hollerith Punched Card Code
• ISO 1681:1973 Information processing - Unpunched paper cards - Specification
• ISO 6586:1980 Data processing - Implementation of the ISO 7- bit and 8- bit coded character sets on punched cards. Defines ISO 7-bit and 8-bit character sets on punched cards as well as the representation of 7-bit and 8-bit combinations on 12-row punched cards. Derived from, and compatible with, the Hollerith Code, insuring compatibility with existing punched card files.

See also

• Computer programming in the punch card era
• Edge-notched card
• History of computing hardware
• Music roll
• Punched tape
• Two Pass Verification

References in popular culture

• Maya Lin makes giant punch card earthwork/public art - looks like a punch card from the air.
• Do Not Fold, Bend, Spindle or Mutilate: Computer Punch Card Art - a unique mail art exhibit by the Washington Pavilion in Sioux Falls, South Dakota.
• The Simpsons - Episode 3F20 "Much Apu About Nothing". Going on to earn his doctorate at the (S)pringfield (H)eights (I)nstitute of (T)echnology, his doctoral dissertation was the world's first computer program to play perfect tic-tac-toe. Bart Simpson ruined it years later by plucking a random punch card out of the box along with several others while commenting, "Hey, what's this one do?". Apu promptly pitched it into the trash.
• Brian De Palma (Director). (1961). 660124: The Story of an IBM Card [Film].

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