A computer punched card reader or just computer card reader is a computer input device used to read

computer programs A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...

in either source or executable form and

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

from

punched cards A punched card (also punch card or punched-card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 18th to 20th centuries, punched cards were wide ...

. 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.

History

Many early computers, such as the

ENIAC ENIAC (; Electronic Numerical Integrator and Computer) was the first Computer programming, programmable, Electronics, electronic, general-purpose digital computer, completed in 1945. Other computers had some of these features, but ENIAC was ...

, and the IBM NORC, provided for punched card input/output. Card readers and punches, either connected to computers or in off-line card to/from

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...

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. Businesses were familiar with storing data on punched cards and

keypunch 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, ...

machines were widely employed. Punched cards were a better fit than other 1950s technologies, such as

, 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.

Operation

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. 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 Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using Electromechanics, electromechanical machines collectively referred to as unit record equipment, electric accounting ...

and used mechanical ''brushes'' that make an electrical contact for a hole, and no contact if there was no hole. 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. 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.

Card readers/punches

Control Data Corporation

* CDC 405 —

CDC 6000 series The CDC 6000 series is a discontinued family of mainframe computers manufactured by Control Data Corporation in the 1960s. It consisted of the CDC 6200, CDC 6300, #Versions, CDC 6400, #Versions, CDC 6500, CDC 6600 and #Versions, CDC 6700 computers, ...

card reader, 1200 or 1600 cards per minute (CPM) * CDC 415 —

card punch, 250 cards per minute

Documation

Documation Inc., of Melbourne, Florida, made card readers for

minicomputer A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...

s in the 1970s: * M-200 card reader, 300 cards/minute also sold by DEC as the CR-11 card reader for the

PDP-11 The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...

* M-600 card reader, 600 cards/minute, also sold by HP as 2892A and 2893A * M-1000-L card reader 1,000 cards/minute Their card readers have been used in elections, including the 2000 "chads" election in Florida.

IBM

* IBM 711 card reader computer peripheral used in the vacuum tube era, 150 or 250 CPM * IBM 2501 card reader, 600 or 1000 CPM * IBM 1402 high speed reader/punch introduced with the

IBM 1401 The IBM 1401 is a variable word length computer, 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 pr ...

, 800 CPM * IBM 1442 reader/punch introduced with the lower-cost IBM 1440, read 80-400 CPM, punch 91-355 CPM * IBM 2540 reader/punch derived from the 1402 that was introduced with System 360 * IBM 2560 Multi-Function Card Machine (MFCM), first introduced for the IBM System/360 Model 20, could also collate, sort and print/interpret. * IBM 3505 reader and its companion 3525 reader/printer/punch that was introduced for the

System/370 The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migrati ...

in 1971, read 1200 CPM, punch 300 CPM

Binary format

For some computer applications, binary formats were used, where each hole represented a single binary digit (or "

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 ...

"), 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 A plugboard or control panel (the term used depends on the application area) is an array of jack (connector), jacks or sockets (often called hubs) into which patch cords can be inserted to complete an electrical circuit. Control panels are som ...

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 The IBM 704 is the model name of a large digital computer, digital mainframe computer introduced by IBM in 1954. Designed by John Backus and Gene Amdahl, it was the first mass-produced computer with hardware for floating-point arithmetic. The I ...

's IBM 714 native card reader, is referred to as Column Binary or Chinese Binary, and used 3 columns for each 36-bit word. Later computers, such as the IBM 1130 or

System/360 The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applicati ...

, used every column. The

'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. 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.

References

Punched card equipment

File:IBM 650 at Texas A&M.jpg, An IBM 650 computer, introduced in 1953, came with the IBM 533 Card Reader/Punch, right. At many IBM 650 installations, punched cards and address 8000 on the console were the only input and output medium. File:IBM Electronic Data Processing Machine - GPN-2000-001881.jpg, IBM 711 card reader on an IBM 704 computer at NASA in 1957 File:BRL61-IBM 1401.jpg, The popular IBM 1401, introduced in 1959 featured a fast card reader/punch, the IBM 1402, left File:NASAComputerRoom7090.NARA.jpg, IBM 711 card readers, far left and foreground, attached to dual IBM 7090s at NASA Mission Control in 1962. File:IBM 2314 DiskDrives and IBM 2540 CardReader Punch.jpg, An IBM 2540 Card Reader Punch at the University of Michigan computer center in 1968 File:DM IBM S360.jpg, Punched card reader/punch on an IBM System/360 Model 20 File:IBM System3 model 10d.jpg, IBM System/3, announced in 1969 introduced a new, smaller punched card and a combined reader/punch/sorter, right File:IBM 7070 (7074).jpg, IBM 7070 with IBM 7501 Console Card Reader, right, based in the IBM 026 keypunch File:Documation card reader.JPG, Documation M-600 card reader {{DEFAULTSORT:Punched card input output Punched card Computing input devices Computer output devices Computing-related lists