Editing Punched card (section)

== Formats ==
The Hollerith punched cards used for the 1890 U.S. census were blank.<ref name="Truedsell_1965"/> Following that, cards commonly had printing such that the row and column position of a hole could be easily seen. Printing could include having fields named and marked by vertical lines, logos, and more.<ref name="IBM_1956"/> "General purpose" layouts (see, for example, the IBM 5081 below) were also available. For applications requiring master cards to be separated from following detail cards, the respective cards had different upper corner diagonal cuts and thus could be separated by a sorter.<ref name="IBM_1962_2"/> Other cards typically had one upper corner diagonal cut so that cards not oriented correctly, or cards with different corner cuts, could be identified.

=== Hollerith's early cards ===
[[File:Hollerith punched card.jpg|thumb|Hollerith card as shown in the ''[[Railroad Gazette]]'' in 1895, with 12 rows and 24 columns.<ref name="Railroad_1895"/>]]

[[Herman Hollerith]] was awarded three patents<ref name="USP395782"/> in 1889 for electromechanical [[tabulating machine]]s. These patents described both [[paper tape]] and rectangular cards as possible recording media. The card shown in {{US patent|src=uspto|395781}} of January 8 was printed with a template and had hole positions 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:

{{blockquote|I was traveling in the West and I had a ticket with what I think was called a punch photograph...the conductor...punched out a description of the individual, as light hair, dark eyes, large nose, etc. So you see, I only made a punch photograph of each person.<ref name="Austrian_1982"/>{{rp|page=15}}}}

When use of the ticket punch proved tiring and error-prone, Hollerith developed the [[pantograph]] "keyboard punch". It featured an enlarged diagram of the card, indicating the positions of the holes to be punched. A printed reading board could be placed under a card that was to be read manually.<ref name="Truedsell_1965"/>{{rp|page=43}}

Hollerith envisioned a number of card sizes. In an article he wrote describing his proposed system for tabulating the [[1890 United States census|1890 U.S. census]], Hollerith suggested a card {{convert|3|by|5+1/2|in|cm}} of [[Manila paper|Manila stock]] "would be sufficient to answer all ordinary purposes."<ref name="Hollerith_1889"/> 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.<ref name="daCruz_2019_2"/> At some point, {{convert|3+1/4|by|7+3/8|in|0}} became the standard card size. These are the dimensions of the [[Federal Reserve Note#Large-size notes|then-current paper currency]] of 1862–1923.<ref name="Littleton"/> This size was needed in order to use available banking-type storage for the 60,000,000 punched cards to come nationwide.<ref name="daCruz_2019_2" />

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. His tabulating machine had up to 40 counters, each with a dial divided into 100 divisions, with two indicator hands; one which stepped one unit with each counting pulse, the other which advanced one unit every time the other dial made a complete revolution. This arrangement allowed a count up to 9,999. During a given tabulating run counters were assigned specific holes or, using [[relay logic]], combination of holes.<ref name="Hollerith_1889"/>

Later designs led to a card with ten rows, each row assigned a digit value, 0 through 9, and 45 columns.<ref name="Bashe-Johnson-Palmer-Pugh_1986"/> 
This card provided for fields to record multi-digit numbers that tabulators could sum, instead of their simply counting cards. Hollerith's 45 column punched cards are illustrated in [[Leslie Comrie|Comrie]]'s ''The application of the Hollerith Tabulating Machine to Brown's Tables of the Moon''.<ref name="Comrie_1932"/>

=== IBM 80-column format and character codes ===
[[File:FortranCardPROJ039.agr.jpg|thumb|Punched card from a [[Fortran]] program: Z(1) = Y + W(1), plus sorting information in the last 8 columns.]]

By the late 1920s, customers wanted to store more data on each punched card. [[Thomas J. Watson|Thomas J. Watson Sr.]], IBM's head, asked two of his top inventors, [[Clair D. Lake]] and [[J. Royden Pierce]], to independently develop ways to increase data capacity without increasing the size of the punched card. Pierce wanted to keep round holes and 45 columns but to allow each column to store more data; Lake suggested rectangular holes, which could be spaced more tightly, allowing 80 columns per punched card, thereby nearly doubling the capacity of the older format.<ref name="Lake_1928"/> Watson picked the latter solution, introduced as ''The IBM Card'', in part because it was compatible with existing tabulator designs and in part because it could be protected by patents and give the company a distinctive advantage.<ref name="IBM_2012"/>

This IBM card format, introduced in 1928,<ref name="IBM_1928"/> has rectangular holes, 80 columns, and 10 rows.<ref name="Pugh_IBM"/> Card size is {{convert|7+3/8|by|3+1/4|in|mm}}. The cards are made of smooth stock, {{convert|0.007|in|um}} thick. There are about 143 cards to the inch ({{#expr:143/2.54round0}}/cm). In 1964, IBM changed from square to round corners.<ref name="IBM_OldNew"/> They come typically in boxes of 2,000 cards<ref name="Boyd_2007"/> or as [[Continuous stationery|continuous form]] cards. Continuous form cards could be both pre-numbered and pre-punched for document control (checks, for example).<ref name="IBM_1953"/>

Initially designed to record responses to [[yes–no question]]s, support for numeric, [[Character encoding|alphabetic and special characters]] was added through the use of columns and zones. The top three positions of a column are called '''zone punching positions''', 12 (top), 11, and 0 (0 may be either a zone punch or a digit punch).<ref name="ReferenceA_1961"/> For decimal data the lower ten positions are called '''digit punching positions''', 0 (top) through 9.<ref name="ReferenceA_1961"/> An arithmetic sign can be specified for a decimal field by '''overpunching''' the field's rightmost column with a zone punch: 12 for plus, 11 for minus (CR). For [[Pound sterling]] [[Coins of the pound sterling#Pre-decimal coinage|pre-decimalization currency]] a [[penny]] column represents the values zero through eleven; 10 (top), 11, then 0 through 9 as above. An arithmetic sign can be punched in the adjacent [[shilling]] column.<ref name="Cemach_1951"/>{{rp|page=9}} Zone punches had other uses in processing, such as indicating a master card.<ref name="IBM_1959_2"/>

[[File:Blue-punch-card-front-horiz.png|thumb|An 80-column punched card with the extended character set introduced with [[EBCDIC]] in 1964.]]

Diagram:<ref name="Iowa_2"/>

<pre style="width:fit-content;white-spacing:nowrap">
    _______________________________________________
   / &-0123456789ABCDEFGHIJKLMNOPQR/STUVWXYZ
12|  x           xxxxxxxxx
11|   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
  |________________________________________________
</pre>
''Note: The 11 and 12 zones were also called the X and Y zones, respectively.''

In 1931, IBM began introducing upper-case letters and special characters (Powers-Samas had developed the first commercial alphabetic punched card representation in 1921).<ref name="Rojas_2001"/><ref name="Pugh_1995"/><ref group="nb" name="NB_Special_characters"/> The 26 letters have two punches (zone [12,11,0] + digit [1–9]). The languages of Germany, Sweden, Denmark, Norway, Spain, Portugal and Finland require up to three additional letters; their punching is not shown here.<ref name="Mackenzie_1980"/>{{rp|pages=88–90}} Most special characters have two or three punches (zone [12,11,0, or none] + digit [2–7] + 8); a few special characters were exceptions: "&" is 12 only, "-" is 11 only, and "/" is 0 + 1). The Space character has no punches.<ref name="Mackenzie_1980"/>{{rp|page=38}} The information represented in a column by a combination of zones [12, 11, 0] and digits [0–9] is dependent on the use of that column. For example, the combination "12-1" is 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" has some other use. The introduction of [[EBCDIC]] in 1964 defined 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 encoding]]s.<ref name="Winter_80"/><ref name="Jones_2"/> 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.<ref name="Mackenzie_1980"/>{{rp|page=7}}

[[File:IBM1130CopyCard.agr.jpg|thumb|[[Binary code|Binary]] punched card.]]

For some computer applications, [[Binary numeral system|binary]] formats were used, where each hole represented a single binary digit (or "[[bit]]"), every column (or row) is treated as a simple [[bit field]], and every combination of holes is permitted.

For example, on the [[IBM 701]]<ref name="IBM_1953_Principles"/> and [[IBM 704]],<ref name="IBM_1955_EDP"/> card data was read, using an [[IBM 711]], into memory in row binary format. For each of the twelve rows of the card, 72 of the 80 columns, skipping the other eight, would be read into two [[36-bit]] words, requiring 864 bits to store the whole card; a control panel was used to select the 72 columns to be read. Software would translate this data into the desired form. One convention was to use columns 1 through 72 for data, and columns 73 through 80 to sequentially number the cards, as shown in the picture above of a punched card for FORTRAN. Such numbered cards could be sorted by machine so that if a deck was dropped the sorting machine could be used to arrange it back in order. This convention continued to be used in FORTRAN, even in later systems where the data in all 80 columns could be read.

The IBM card readers 3504, [[IBM 3505|3505]] and the multifunction unit 3525 used a different encoding scheme for column binary data, also known as [[card image]], where each column, split into two rows of 6 (12–3 and 4–9) was encoded into two 8-bit bytes, holes in each group represented by bits 2 to 7 (MSb [[Bit numbering|numbering]], bit 0 and 1 unused ) in successive bytes. This required 160 8-bit bytes, or 1280 bits, to store the whole card.<ref name="IBM GA21-9124-5" />

As an aid to humans who had to deal with the punched cards, the IBM 026 and later 029 and 129 key punch machines could print human-readable text above each of the 80 columns.

[[File:IBM lace card.jpg|thumb|left|Invalid "lace cards" such as this pose mechanical problems for card readers.]]

As a prank, punched cards could be made where every possible punch position had a hole. Such "[[lace card]]s" lacked structural strength, and would frequently buckle and jam inside the machine.<ref name="Raymond_1991"/>

The IBM 80-column punched card format dominated the industry, becoming known as just '''IBM cards''', even though other companies made cards and equipment to process them.<ref name="Maxfield_2011"/>

[[File:Punch-card-5081.jpg|thumb|A 5081 card from a non-IBM manufacturer.]]

One of the most common punched card formats is the IBM 5081 card format, a general purpose layout with no field divisions. This format has digits printed on it corresponding to the punch positions of the digits in each of the 80 columns. Other punched card vendors manufactured cards with this same layout and number.

=== IBM ''Stub card'' and ''Short card'' formats ===
Long cards were available with a scored stub on either end which, when torn off, left an 80 column card. The torn off card is called a ''stub card''.

80-column cards were available scored, on either end, creating both a ''short card'' and a ''stub card'' when torn apart. Short cards can be processed by other IBM machines.<ref name="IBM_1953"/><ref name="IBM_1965_2"/> A common length for stub cards was 51 columns. Stub cards were used in applications requiring tags, labels, or carbon copies.<ref name="IBM_1953"/>

=== IBM 40-column Port-A-Punch card format ===
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.''<ref name="IBM_2003_3"/>
<gallery>
File:IBM Port-A-Punch.jpg|IBM Port-A-Punch
File:FORTRAN Port-A-Punch card. Compiler directive "SQUEEZE" removed the alternating blank columns from the input. Godfrey Manning..jpg|FORTRAN Port-A-Punch card. Compiler directive "SQUEEZE" removed the alternating blank columns from the input.
File:IBM Port-a-punch.jpg|Port-a-punch
</gallery>

=== IBM 96-column format ===
[[File:System 3 punch card.jpg|thumb|IBM 96-column punched card]]
In 1969 IBM introduced a new, smaller, round-hole, 96-column card format along with the [[IBM System/3]] low-end business computer. These cards have tiny, 1&nbsp;mm diameter circular holes, smaller than those in [[Punched tape|paper tape]]. Data is stored in 6-bit [[BCD (character encoding)|BCD]], 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 coded data.<ref name="Winter_96"/> As in the 80 column card, readable text was printed in the top section of the card. There was also a 4th row of 32 characters that could be printed. This format was never widely used; it was IBM-only, but they did not support it on any equipment beyond the System/3, where it was quickly superseded by the 1973 [[IBM 3740|IBM 3740 Data Entry System]] using [[Floppy disk#8-inch floppy disk|8-inch floppy disks]].

The format was however recycled in 1978 when IBM re-used the mechanism in its [[IBM 3624]] [[ATM]]s as print-only receipt printers.

=== Powers/Remington Rand/UNIVAC 90-column format ===
[[File:RemingtonRandCard.agr.jpg|thumb|left|A blank [[Remington Rand]] [[UNIVAC]] format card. Card courtesy of [[MIT Museum]].]]
[[File:Remington Rand punched card.mw.jpg|thumb|A punched Remington Rand card with an IBM card for comparison]]

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 80 column format from 1928 by coding two characters in each of the 45 columns – producing what is now commonly called the 90-column card.<ref name="Aspray_1990"/>{{rp|page=142}} There are two sets of six rows across each card. The rows in each set are labeled 0, 1/2, 3/4, 5/6, 7/8 and 9. The even numbers in a pair are formed by combining that punch with a 9 punch. Alphabetic and special characters use 3 or more punches.<ref name="Quadibloc"/><ref name="Winter_90"/>

=== Powers-Samas formats ===
The British [[Powers-Samas]] company used a variety of card formats for their [[unit record equipment]]. They began with 45 columns and round holes. Later 36, 40 and 65 column cards were provided. A 130 column card was also available – formed by dividing the card into two rows, each row with 65 columns and each character space with 5 punch positions. A 21 column card was comparable to the IBM Stub card.<ref name="Cemach_1951"/>{{rp|pages=47–51}}

=== Mark sense format ===
[[File:HP Educational Basic optical mark-reader card. Godfrey Manning..jpg|thumb|left|HP Educational Basic optical mark-reader card.]]

[[Mark sense]] ([[electrographic]]) cards, developed by [[Reynold B. Johnson]] at IBM,<ref name="Fisher_1998"/> have printed ovals that could be marked with a special electrographic pencil. Cards would typically be punched with some initial information, such as the name and location of an inventory item. Information to be added, such as quantity of the item on hand, would be marked in the ovals. Card punches with an option to detect mark sense cards could then punch the corresponding information into the card.

=== Aperture format ===
[[File:Aperture card.JPG|thumb|[[Aperture card]]]]

[[Aperture card]]s have a cut-out hole on the right side of the punched card. A piece of 35&nbsp;mm microfilm containing a [[microform]] image is mounted in the hole. Aperture cards are used for [[engineering drawing]]s from all engineering disciplines. Information about the drawing, for example the drawing number, is typically punched and printed on the remainder of the card.