A computer punched card reader or just computer card reader is a computer input device used to read computer programs in either source or executable form and data from punched cards. A computer card punch is a computer output device that punches holes in cards. Sometimes computer punch card readers were combined with computer card punches and, later, other devices to form multifunction machines.
Many early computers, such as the ENIAC, and the IBM NORC, provided for punched card input/output. [1] Card readers and punches, either connected to computers or in off-line card to/from magnetic tape configurations, were ubiquitous through the mid-1970s.
Punched cards had been in use since the 1890s; their technology was mature and reliable. Card readers and punches developed for punched card machines were readily adaptable for computer use. [2] Businesses were familiar with storing data on punched cards and keypunch machines were widely employed. Punched cards were a better fit than other 1950s technologies, such as magnetic tape, for some computer applications because individual cards could easily be updated without having to access a computer. Also file drawers of punched cards served as a low-density offline storage medium for data.
The standard measure of speed is cards per minute, abbreviated CPM: The number of cards which can be read or punched in one minute. Card reader models vary from 150 to around 2,000 CPM. [3] [4] At 1200 CPM, i.e. 20 cards per second, this translates to 1,600 characters per second (CPS), assuming all 80 columns of each card encode information.
Early computer card readers were base on electromechanical unit record equipment and used mechanical brushes that make an electrical contact for a hole, and no contact if no punch. Later readers used photoelectric sensors to detect the presence or absence of a hole. Timing within each read cycle relates the resulting signals to the corresponding position on the card. Early readers read cards in parallel, row by row, following unit record practice (hence the orientation of the rectangular holes). Later, card readers that read cards serially, column by column became more common.
Card punches necessarily run more slowly to allow for the mechanical action of punching, up to around 300 CPM or 400 characters per second. [5]
Some card devices offer the ability to interpret, or print a line on the card displaying the data that is punched. Typically this slows down the punch operation. Many punches would read the card just punched and compare its actual contents to the original data punched, to protect against punch errors. Some devices allowed data to be read from a card and additional information to be punched into the same card.
Readers and punches include a hopper for input cards and one or more stacker bins to collect cards read or punched. A function called stacker select allows the controlling computer to choose which stacker a card just read or punched will be placed into.
Documation Inc., of Melbourne, Florida, made card readers for minicomputers in the 1970s:
Their card readers have been used in elections, [11] including the 2000 "chads" election in Florida. [12]
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 bitfield, and every combination of holes is 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 is 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.
An alternative format, used by the IBM 704's IBM 714 native card reader, is referred to as Column Binary or Chinese Binary, and used 3 columns for each 36-bit word. [14] Later computers, such as the IBM 1130 or System/360, used every column. The IBM 1401's card reader could be used in Column Binary mode, which stored two characters in every column, or one 36-bit word in three columns when used as input device for other computers. However, most of the older card punches were not intended to punch more than 3 holes in a column. The multipunch key is used to produce binary cards, or other characters not on the keypunch keyboard. [15]
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. [16]
A 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.
The IBM 1401 is a variable-wordlength decimal computer that was announced by IBM on October 5, 1959. The first member of the highly successful IBM 1400 series, it was aimed at replacing unit record equipment for processing data stored on punched cards and at providing peripheral services for larger computers. The 1401 is considered by IBM to be the Ford Model-T of the computer industry due to its mass appeal. Over 12,000 units were produced and many were leased or resold after they were replaced with newer technology. The 1401 was withdrawn on February 8, 1971.
UNIVAC was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and successor organizations.
IBM 1442 is a combination IBM card reader and card punch. It reads and punches 80-column IBM-format punched cards and is used on the IBM 1440, the IBM 1130, the IBM 1800 and System/360 and is an option on the IBM System/3.
The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding the decimal IBM 1620 in that market segment. Typical installations included a 1 megabyte disk drive that stored the operating system, compilers and object programs, with program source generated and maintained on punched cards. Fortran was the most common programming language used, but several others, including APL, were available.
Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using electromechanical machines collectively referred to as unit record equipment, electric accounting machines (EAM) or tabulating machines. Unit record machines came to be as ubiquitous in industry and government in the first two-thirds of the twentieth century as computers became in the last third. They allowed large volume, sophisticated data-processing tasks to be accomplished before electronic computers were invented and while they were still in their infancy. This data processing was accomplished by processing punched cards through various unit record machines in a carefully choreographed progression. This progression, or flow, from machine to machine was often planned and documented with detailed flowcharts that used standardized symbols for documents and the various machine functions. All but the earliest machines had high-speed mechanical feeders to process cards at rates from around 100 to 2,000 per minute, sensing punched holes with mechanical, electrical, or, later, optical sensors. The operation of many machines was directed by the use of a removable plugboard, control panel, or connection box. Initially all machines were manual or electromechanical. The first use of an electronic component was in 1937 when a photocell was used in a Social Security bill-feed machine. Electronic components were used on other machines beginning in the late 1940s.
A keypunch is a device for precisely punching holes into stiff paper cards at specific locations as determined by keys struck by a human operator. Other devices included here for that same function include the gang punch, the pantograph punch, and the stamp. The term was also used for similar machines used by humans to transcribe data onto punched tape media.
The IBM System/3 was an IBM midrange computer introduced in 1969, and marketed until 1985. It was produced by IBM Rochester in Minnesota as a low-end business computer aimed at smaller organizations that still used IBM 1400 series computers or unit record equipment. The first member of what IBM refers to as their "midrange" line, it also introduced the RPG II programming language. It is the first ancestor in the product line whose current version is the IBM i series and includes the highly successful AS/400.
The tabulating machine was an electromechanical machine designed to assist in summarizing information stored on punched cards. Invented by Herman Hollerith, the machine was developed to help process data for the 1890 U.S. Census. Later models were widely used for business applications such as accounting and inventory control. It spawned a class of machines, known as unit record equipment, and the data processing industry.
IBM 7070 is a decimal-architecture intermediate data-processing system that was introduced by IBM in 1958. It was part of the IBM 700/7000 series, and was based on discrete transistors rather than the vacuum tubes of the 1950s. It was the company's first transistorized stored-program computer.
From the invention of computer programming languages up to the mid-1970s, most computer programmers created, edited and stored their programs line by line on punch cards.
The IBM 2540 is a punched-card computer peripheral manufactured by IBM Corporation for use of System/360 and later computer systems. The 2540 was designed by IBM's Data Processing Division in Rochester, Minnesota, and was introduced in 1965. The 2540 can read punched-cards at 1000 cards per minute (CPM) and punch at 300 CPM. The 2540 is based on the design of the older, slightly slower, 1402.
The IBM 2780 and the IBM 3780 are devices developed by IBM to perform remote job entry (RJE) and other batch functions over telephone lines; they communicate with the mainframe via Binary Synchronous Communications and replaced older terminals using synchronous transmit-receive (STR). In addition, IBM has developed workstation programs for the 1130, 360/20, 2922, System/360 other than 360/20, System/370 and System/3.
The IBM 1402 was a high speed card reader/punch introduced on October 5, 1959 as a peripheral input/output device for the IBM 1401 computer. It was later used with other computers of the IBM 1400 series and IBM 7000 series product lines. It was adapted as the IBM 1622 Card Read-Punch for the IBM 1620 and provided the basic design for the models 2501, 2520 and 2540 equipment used with the IBM System/360 product line.
The IBM 533 Input-Output Unit, announced on July 2, 1953, was a punched card reader and punch that served as the primary input-output unit for the IBM 650 computer. It had two independent card paths, one for reading and one for punching. IBM cards were fed face down, 12-edge first. All 80 columns could be read and punched by the computer as numeric data, but alphanumeric reading was severely limited on the basic 650 and require special control panel wiring.
The IBM System/360 Model 20 is the smallest member of the IBM System/360 family announced in November 1964. The Model 20 supports only a subset of the System/360 instruction set, with binary numbers limited to 16 bits and no floating point. In later years it would have been classified as a 16-bit minicomputer rather than a mainframe, but the term "minicomputer" was not current, and in any case IBM wanted to emphasize the compatibility of the Model 20 rather than its differences from the rest of the System/360 line. It does, however, have the full System/360 decimal instruction set, that allows for addition, subtraction, product, and dividend of up to 31 decimal digits.
The IBM 711 was a punched card reader used as a peripheral device for IBM mainframe vacuum tube computers and early transistorized computers. Announced on May 21, 1952, it was first shipped with the IBM 701. Later IBM computers that used it were the IBM 704, the IBM 709, and the transistorized IBM 7090 and 7094.
The IBM 2501 is a punched-card reader from IBM with models for the System/360 and System/370 mainframe systems and for the IBM System/360 Model 20, the IBM 1130 and IBM System/3 minicomputers. 2501 models can read 80-column cards at either 600 or 1000 cards per minute (CPM).
The IBM 3505 is a reader for 80-column punched cards. It can read cards punched in EBCDIC or column binary at up to 1200 cards per minute (CPM). The IBM 3525 is a multi-function punched card device, capable of reading, punching, and printing on punched cards. The 3505 contains an integrated control unit that attaches to a System/370 byte multiplexer, selector, or block multiplexer channel. An optional feature of the 3505 allows the control unit to also control a 3525, although the two are separately-addressed devices.
