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76-437: Several standards existed for feature connectors, depending on the bus and graphics card type. Most of them were simply an 8, 16 or 32- bit wide internal connector, transferring data between the graphics card and another device, bypassing the system's CPU and memory completely. Their speeds often far exceeded the speed of normal ISA or even early PCI buses, e.g. 40 MB/s for a standard ISA-based SVGA , up to 150 MB/s for

152-600: A binit as an arbitrary information unit equivalent to some fixed but unspecified number of bits. Punched card A punched card (also punch card or punched-card ) is a piece of card stock that stores digital data using punched holes. Punched cards were once common in data processing and the control of automated machines . Punched cards were widely used in the 20th century, where unit record machines , organized into data processing systems , used punched cards for data input, output, and storage. The IBM 12-row/80-column punched card format came to dominate

228-409: A byte or word , is referred to, it is usually specified by a number from 0 upwards corresponding to its position within the byte or word. However, 0 can refer to either the most or least significant bit depending on the context. Similar to torque and energy in physics; information-theoretic information and data storage size have the same dimensionality of units of measurement , but there

304-509: A field . The first card of a group of cards, containing fixed or indicative information for that group, is known as a master card . Cards that are not master cards are detail cards . The Hollerith punched cards used for the 1890 U.S. census were blank. 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. "General purpose" layouts (see, for example,

380-440: 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. Zone punches had other uses in processing, such as indicating a master card. Diagram: 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

456-502: A unit of information , the bit is also known as a shannon , named after Claude E. Shannon . The symbol for the binary digit is either "bit", per the IEC 80000-13 :2008 standard, or the lowercase character "b", per the IEEE 1541-2002 standard. Use of the latter may create confusion with the capital "B" which is the international standard symbol for the byte. The encoding of data by discrete bits

532-482: A Bell Labs memo on 9 January 1947 in which he contracted "binary information digit" to simply "bit". A bit can be stored by a digital device or other physical system that exists in either of two possible distinct states . These may be the two stable states of a flip-flop , two positions of an electrical switch , two distinct voltage or current levels allowed by a circuit , two distinct levels of light intensity , two directions of magnetization or polarization ,

608-478: A VESA-based or PCI-based one, while the standard 16 bit ISA bus ran at ~5.3 MB/s and the VESA bus at up to 160 MB/s bandwidth. The feature connector bandwidths were far beyond the capabilities of e.g. a 386 , 486 and barely handled by an early Pentium . Depending on the implementation, it could be uni or bi-directional, and carry analog color information as well as data. Unlike analog overlay devices however,

684-429: A bit was represented by the polarity of magnetization of a certain area of a ferromagnetic film, or by a change in polarity from one direction to the other. The same principle was later used in the magnetic bubble memory developed in the 1980s, and is still found in various magnetic strip items such as metro tickets and some credit cards . In modern semiconductor memory , such as dynamic random-access memory ,

760-420: A column are called zone punching positions , 12 (top), 11, and 0 (0 may be either a zone punch or a digit punch). For decimal data the lower ten positions are called digit punching positions , 0 (top) through 9. 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 pre-decimalization currency

836-435: 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. In 1969 IBM introduced

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912-514: A feature connector carried mainly data and essentially allowed an expansion card to access the graphics card Video RAM directly, although directing this data stream to the system's CPU and RAM was not always possible, limiting its usefulness mainly to display purposes. Although its use rapidly declined after the introduction of the faster AGP internal bus, it was, at its time, the only feasible way to connect certain types of graphics-intensive devices to an average computing system without exceeding

988-513: A magnetic tape encoder in 1965, a system marketed as a keypunch replacement which was somewhat successful. Punched cards were still commonly used for entering both data and computer programs 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 these roles as well. However, their influence lives on through many standard conventions and file formats. The terminals that replaced

1064-578: A method of recording and playing back performances on a harmonium using punched cards. The system was called the Mélographe Répétiteur and "writes down ordinary music played on the keyboard dans le langage de Jacquard", that is as holes punched in a series of cards. By 1887 Carpentier had separated the mechanism into the Melograph which recorded the player's key presses and the Melotrope which played

1140-469: A new, smaller, round-hole, 96-column card format along with the IBM System/3 low-end business computer. These cards have tiny, 1 mm diameter circular holes, smaller than those in paper tape . Data is stored in 6-bit 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

1216-484: A pair are formed by combining that punch with a 9 punch. Alphabetic and special characters use 3 or more punches. 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

1292-467: A powerful tool for business data-processing. By 1950 punched cards had become ubiquitous in industry and government. "Do not fold, spindle or mutilate," a warning that appeared on some punched cards distributed as documents such as checks and utility bills to be returned for processing, became a motto for the post- World War II era. In 1956 IBM signed a consent decree requiring, amongst other things, that IBM would by 1962 have no more than one-half of

1368-574: A service and that the cards were part of the machine. IBM fought all the way to the Supreme Court and lost in 1936; the court ruled that IBM could only set card specifications. "By 1937... IBM had 32 presses at work in Endicott, N.Y., printing, cutting and stacking five to 10 million punched cards every day." Punched cards were even used as legal documents, such as U.S. Government checks and savings bonds. During World War II punched card equipment

1444-404: A time in serial transmission , and by a multiple number of bits in parallel transmission . A bitwise operation optionally processes bits one at a time. Data transfer rates are usually measured in decimal SI multiples of the unit bit per second (bit/s), such as kbit/s. In the earliest non-electronic information processing devices, such as Jacquard's loom or Babbage's Analytical Engine , a bit

1520-475: A variety of punched cards and unit record machines for creating, sorting, and tabulating punched cards, even after the development of electronic computers in the 1950s. Both IBM and Remington Rand tied punched card purchases to machine leases, a violation of the US 1914 Clayton Antitrust Act . In 1932, the US government took both to court on this issue. Remington Rand settled quickly. IBM viewed its business as providing

1596-670: Is 12 only, "-" is 11 only, and "/" is 0 + 1). The Space character has no punches. 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 encodings . A 1969 American National Standard defined

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1672-535: 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. A common length for stub cards was 51 columns. Stub cards were used in applications requiring tags, labels, or carbon copies. According to the IBM Archive: IBM's Supplies Division introduced the Port-A-Punch in 1958 as

1748-486: Is in general no meaning to adding, subtracting or otherwise combining the units mathematically, although one may act as a bound on the other. Units of information used in information theory include the shannon (Sh), the natural unit of information (nat) and the hartley (Hart). One shannon is the maximum amount of information needed to specify the state of one bit of storage. These are related by 1 Sh ≈ 0.693 nat ≈ 0.301 Hart. Some authors also define

1824-554: Is more compressed—the same bucket can hold more. For example, it is estimated that the combined technological capacity of the world to store information provides 1,300 exabytes of hardware digits. However, when this storage space is filled and the corresponding content is optimally compressed, this only represents 295 exabytes of information. When optimally compressed, the resulting carrying capacity approaches Shannon information or information entropy . Certain bitwise computer processor instructions (such as bit set ) operate at

1900-483: Is named Zoomed video port . Bit The bit is the most basic unit of information in computing and digital communication . The name is a portmanteau of binary digit . The bit represents a logical state with one of two possible values . These values are most commonly represented as either " 1 " or " 0 " , but other representations such as true / false , yes / no , on / off , or + / − are also widely used. The relation between these values and

1976-456: The IBM 701 and IBM 704 , 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

2052-531: 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. 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 by 5 + 1 ⁄ 2 inches (7.6 by 14.0 cm) of Manila stock "would be sufficient to answer all ordinary purposes." The cards used in

2128-410: The yottabit (Ybit). When the information capacity of a storage system or a communication channel is presented in bits or bits per second , this often refers to binary digits, which is a computer hardware capacity to store binary data ( 0 or 1 , up or down, current or not, etc.). Information capacity of a storage system is only an upper bound to the quantity of information stored therein. If

2204-499: 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. At some point, 3 + 1 ⁄ 4 by 7 + 3 ⁄ 8 inches (83 by 187 mm) became the standard card size. These are the dimensions of the then-current paper currency of 1862–1923. This size was needed in order to use available banking-type storage for

2280-778: The 1920s they had units for carrying out basic arithmetic operations. Hollerith founded the Tabulating Machine Company (1896) which was one of four companies that were amalgamated via stock acquisition to form a fifth company, Computing-Tabulating-Recording Company (CTR) in 1911, later renamed International Business Machines Corporation (IBM) in 1924. Other companies entering the punched card business included The Tabulator Limited (Britain, 1902), Deutsche Hollerith-Maschinen Gesellschaft mbH (Dehomag) (Germany, 1911), Powers Accounting Machine Company (US, 1911), Remington Rand (US, 1927), and H.W. Egli Bull (France, 1931). These companies, and others, manufactured and marketed

2356-449: The 1940s, computer builders experimented with a variety of storage methods, such as pressure pulses traveling down a mercury delay line , charges stored on the inside surface of a cathode-ray tube , or opaque spots printed on glass discs by photolithographic techniques. In the 1950s and 1960s, these methods were largely supplanted by magnetic storage devices such as magnetic-core memory , magnetic tapes , drums , and disks , where

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2432-422: The 60,000,000 punched cards to come nationwide. 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

2508-701: The Hollerith Tabulating Machine to Brown's Tables of the Moon . By the late 1920s, customers wanted to store more data on each punched card. 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

2584-447: 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. Other cards typically had one upper corner diagonal cut so that cards not oriented correctly, or cards with different corner cuts, could be identified. Herman Hollerith

2660-409: The ambiguity of relying on the underlying hardware design, the unit octet was defined to explicitly denote a sequence of eight bits. Computers usually manipulate bits in groups of a fixed size, conventionally named " words ". Like the byte, the number of bits in a word also varies with the hardware design, and is typically between 8 and 80 bits, or even more in some specialized computers. In

2736-575: The available CPU power and memory bandwidth, and without the disadvantages and limitations of a purely analog overlay. The idea of accessing a video card's memory directly resurfaced with the introduction of the Scan-Line Interleave (3dfx SLI) technology, although this technology is aimed at connecting two equally powered and complete graphic cards to produce a single, increased performance visual output, and not e.g. directly interfacing TV tuner cards. A variant of that idea, born for PCMCIA Card ,

2812-424: The average. This principle is the basis of data compression technology. Using an analogy, the hardware binary digits refer to the amount of storage space available (like the number of buckets available to store things), and the information content the filling, which comes in different levels of granularity (fine or coarse, that is, compressed or uncompressed information). When the granularity is finer—when information

2888-544: The capacity of the older format. 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. This IBM card format, introduced in 1928, has rectangular holes, 80 columns, and 10 rows. Card size is 7 + 3 ⁄ 8 by 3 + 1 ⁄ 4 inches (187 by 83 mm). The cards are made of smooth stock, 0.007 inches (180 μm) thick. There are about 143 cards to

2964-425: The card. IBM's Fred M. Carroll developed a series of rotary presses that were used to produce punched cards, including a 1921 model that operated at 460 cards per minute (cpm). In 1936 he introduced a completely different press that operated at 850 cpm. Carroll's high-speed press, containing a printing cylinder, revolutionized the company's manufacturing of punched cards. It is estimated that between 1930 and 1950,

3040-410: The corresponding information into the card. Aperture cards have a cut-out hole on the right side of the punched card. A piece of 35 mm microfilm containing a microform image is mounted in the hole. Aperture cards are used for engineering drawings from all engineering disciplines. Information about the drawing, for example the drawing number, is typically punched and printed on the remainder of

3116-415: The early 21st century, retail personal or server computers have a word size of 32 or 64 bits. The International System of Units defines a series of decimal prefixes for multiples of standardized units which are commonly also used with the bit and the byte. The prefixes kilo (10 ) through yotta (10 ) increment by multiples of one thousand, and the corresponding units are the kilobit (kbit) through

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3192-436: The first commercial alphabetic punched card representation in 1921). 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. Most special characters have two or three punches (zone [12,11,0, or none] + digit [2–7] + 8); a few special characters were exceptions: "&"

3268-451: The inch (56/cm). In 1964, IBM changed from square to round corners. They come typically in boxes of 2,000 cards or as continuous form cards. Continuous form cards could be both pre-numbered and pre-punched for document control (checks, for example). Initially designed to record responses to yes–no questions , support for numeric, alphabetic and special characters was added through the use of columns and zones. The top three positions of

3344-468: The industry. Many early digital computers used punched cards as the primary medium for input of both computer programs and data . Data can be entered onto a punched card using a keypunch . While punched cards are now obsolete as a storage medium , as of 2012, some voting machines still used punched cards to record votes. Punched cards also had a significant cultural impact in the 20th century. The idea of control and data storage via punched holes

3420-409: The level of manipulating bits rather than manipulating data interpreted as an aggregate of bits. In the 1980s, when bitmapped computer displays became popular, some computers provided specialized bit block transfer instructions to set or copy the bits that corresponded to a given rectangular area on the screen. In most computers and programming languages, when a bit within a group of bits, such as

3496-560: The mechanism. In 1804 Joseph Marie Jacquard demonstrated a mechanism to automate loom operation. A number of punched cards were linked into a chain of any length. Each card held the instructions for shedding (raising and lowering the warp ) and selecting the shuttle for a single pass. Semyon Korsakov was reputedly the first to propose punched cards in informatics for information store and search. Korsakov announced his new method and machines in September 1832. Charles Babbage proposed

3572-454: 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. 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

3648-435: 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. Long cards were available with a scored stub on either end which, when torn off, left an 80 column card. The torn off card

3724-426: 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 numbering , bit 0 and 1 unused ) in successive bytes. This required 160 8-bit bytes, or 1280 bits, to store the whole card. As an aid to humans who had to deal with

3800-443: The music. At the end of the 1800s Herman Hollerith created a method for recording data on a medium that could then be read by a machine, developing punched card data processing technology for the 1890 U.S. census . His tabulating machines read and summarized data stored on punched cards and they began use for government and commercial data processing. Initially, these electromechanical machines only counted holes, but by

3876-436: The number of character positions available, e.g. 80-column card . A sequence of cards that is input to or output from some step in an application's processing is called a card deck or simply deck . The rectangular, round, or oval bits of paper punched out were called chad ( chads ) or chips (in IBM usage). Sequential card columns allocated for a specific use, such as names, addresses, multi-digit numbers, etc., are known as

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3952-408: The orientation of reversible double stranded DNA , etc. Bits can be implemented in several forms. In most modern computing devices, a bit is usually represented by an electrical voltage or current pulse, or by the electrical state of a flip-flop circuit. For devices using positive logic , a digit value of 1 (or a logical value of true) is represented by a more positive voltage relative to

4028-574: 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. Later designs led to a card with ten rows, each row assigned a digit value, 0 through 9, and 45 columns. 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 Comrie 's The application of

4104-443: The physical states of the underlying storage or device is a matter of convention, and different assignments may be used even within the same device or program . It may be physically implemented with a two-state device. A contiguous group of binary digits is commonly called a bit string , a bit vector, or a single-dimensional (or multi-dimensional) bit array . A group of eight bits is called one  byte , but historically

4180-587: 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 . The Univac UNITYPER introduced magnetic tape for data entry in the 1950s. 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. Mohawk Data Sciences introduced

4256-632: 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. 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" or, later, "punched card" at first mention in its documentation and thereafter simply "card" or "cards". Specific formats were often indicated by

4332-508: 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. As a prank, punched cards could be made where every possible punch position had a hole. Such " lace cards " lacked structural strength, and would frequently buckle and jam inside the machine. 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. One of

4408-469: The punches for 128 characters and was named the Hollerith Punched Card Code (often referred to simply as Hollerith Card Code ), honoring Hollerith. For some computer applications, 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

4484-517: The representation of 0 . Different logic families require different voltages, and variations are allowed to account for component aging and noise immunity. For example, in transistor–transistor logic (TTL) and compatible circuits, digit values 0 and 1 at the output of a device are represented by no higher than 0.4 V and no lower than 2.6 V, respectively; while TTL inputs are specified to recognize 0.8 V or below as 0 and 2.2 V or above as 1 . Bits are transmitted one at

4560-424: The size of the byte is not strictly defined. Frequently, half, full, double and quadruple words consist of a number of bytes which is a low power of two. A string of four bits is usually a nibble . In information theory , one bit is the information entropy of a random binary variable that is 0 or 1 with equal probability, or the information that is gained when the value of such a variable becomes known. As

4636-552: The thickness of alternating black and white lines. The bit is not defined in the International System of Units (SI). However, the International Electrotechnical Commission issued standard IEC 60027 , which specifies that the symbol for binary digit should be 'bit', and this should be used in all multiples, such as 'kbit', for kilobit. However, the lower-case letter 'b' is widely used as well and

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4712-556: The two possible values of one bit of storage are not equally likely, that bit of storage contains less than one bit of information. If the value is completely predictable, then the reading of that value provides no information at all (zero entropic bits, because no resolution of uncertainty occurs and therefore no information is available). If a computer file that uses n  bits of storage contains only m  <  n  bits of information, then that information can in principle be encoded in about m  bits, at least on

4788-444: The two values of a bit may be represented by two levels of electric charge stored in a capacitor . In certain types of programmable logic arrays and read-only memory , a bit may be represented by the presence or absence of a conducting path at a certain point of a circuit. In optical discs , a bit is encoded as the presence or absence of a microscopic pit on a reflective surface. In one-dimensional bar codes , bits are encoded as

4864-478: The use of "Number Cards", "pierced with certain holes and stand[ing] opposite levers connected with a set of figure wheels ... advanced they push in those levers opposite to which there are no holes on the cards and thus transfer that number together with its sign" in his description of the Calculating Engine's Store. There is no evidence that he built a practical example. In 1881, Jules Carpentier developed

4940-447: Was also used in Morse code (1844) and early digital communications machines such as teletypes and stock ticker machines (1870). Ralph Hartley suggested the use of a logarithmic measure of information in 1928. Claude E. Shannon first used the word "bit" in his seminal 1948 paper " A Mathematical Theory of Communication ". He attributed its origin to John W. Tukey , who had written

5016-438: Was awarded three patents in 1889 for electromechanical 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 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

5092-532: Was comparable to the IBM Stub card. Mark sense ( electrographic ) cards, developed by Reynold B. Johnson at IBM, 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

5168-450: Was developed independently on several occasions in the modern period. In most cases there is no evidence that each of the inventors was aware of the earlier work. Basile Bouchon developed the control of a loom by punched holes in paper tape in 1725. The design was improved by his assistant Jean-Baptiste Falcon and by Jacques Vaucanson . Although these improvements controlled the patterns woven, they still required an assistant to operate

5244-460: Was often stored as the position of a mechanical lever or gear, or the presence or absence of a hole at a specific point of a paper card or tape . The first electrical devices for discrete logic (such as elevator and traffic light control circuits , telephone switches , and Konrad Zuse's computer) represented bits as the states of electrical relays which could be either "open" or "closed". When relays were replaced by vacuum tubes , starting in

5320-503: Was originally inspired by railroad tickets that let the conductor encode a rough description of the passenger: 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. When use of the ticket punch proved tiring and error-prone, Hollerith developed

5396-515: Was quickly superseded by the 1973 IBM 3740 Data Entry System using 8-inch floppy disks . 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. 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

5472-503: Was recommended by the IEEE 1541 Standard (2002) . In contrast, the upper case letter 'B' is the standard and customary symbol for byte. Multiple bits may be expressed and represented in several ways. For convenience of representing commonly reoccurring groups of bits in information technology, several units of information have traditionally been used. The most common is the unit byte , coined by Werner Buchholz in June 1956, which historically

5548-511: 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, 3505 and

5624-651: Was used by the Allies in some of their efforts to decrypt Axis communications. See, for example, Central Bureau in Australia. At Bletchley Park in England, "some 2 million punched cards a week were being produced, indicating the sheer scale of this part of the operation". In Nazi Germany, punched cards were used for the censuses of various regions and other purposes (see IBM and the Holocaust ). Punched card technology developed into

5700-541: Was used in the punched cards invented by Basile Bouchon and Jean-Baptiste Falcon (1732), developed by Joseph Marie Jacquard (1804), and later adopted by Semyon Korsakov , Charles Babbage , Herman Hollerith , and early computer manufacturers like IBM . A variant of that idea was the perforated paper tape . In all those systems, the medium (card or tape) conceptually carried an array of hole positions; each position could be either punched through or not, thus carrying one bit of information. The encoding of text by bits

5776-405: Was used to represent the group of bits used to encode a single character of text (until UTF-8 multibyte encoding took over) in a computer and for this reason it was used as the basic addressable element in many computer architectures . The trend in hardware design converged on the most common implementation of using eight bits per byte, as it is widely used today. However, because of

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