Punch card

a punch card is in the today's sense a mechanical storage medium for data.

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origin

Lochkartonsteuerung einer Tanzorgel
hole cardboard price increase of a dance organ

punch cards and punch cardsimilar systems become offfor instance the center 18. Century within the range of automation and the data processing uses. To repeat it usually assigned around recurring operational sequence rationally. Among other things card-controlled looms were built, whereby the first punch cards were here wooden panels. Drehorgelnoften this very day with punch cardsimilar storage media (so-called folding carton notes or punched tape roles) are steered, in addition, other automatic and part-automatic music instruments avail themselves of this procedure. Charles Babbage planned a punch card control for its Analytical engine. Early data processing - and - register-lay close are withoutNot to think punch cards.

The origins of the punch card go along on the function mode by play doses and other automats back, pins or holes the automated rendition of music pieces and the control attached in those a turning roller or disk on itmechanical operational sequence made possible.

The basic principle of the data storage of a punch card is that the data in suitable form, relevant for a special function of an automat , are coded . For example into out thin cardboard an existing storage medium holes are punched, their position ofrespective code one gives. In order to then implement the function at any time, the holes of the storage medium are read off by a Leseeinheit and decoded by a suitable device suitably, so that they can be assigned to the function. The scanning thatControl instructions can happen on mechanical, pneumatic, opto electrical or also electromechanical way.

Mechanical and also electromechanical memory systems, which store data by holes in an external medium from paper, cardboard or the like, offered before the development of the electronic data processing contrary toSystems as for instance the pin roller, the most economical possibility, coded data fast to multiply and with simple means a new code to write.

Into the 1990er there were years so-called edge punched cards, which were worked on manually. Different search criteria (for examplein the library nature) with holes or slots at all 4 edges of the map were coded. One could sting with a long needle into the position of a search criterion and pull the selected maps out of the pile.

Hollerith punch card

laterin the computer range far spread punch card format decreases/goes back on the US-American census 1890 , to which Herman Hollerith developed a procedure including the associated punching and evaluation machines (Hollerithmaschine), which is based on punch cards. The punch card became after its mass premiere, the census, particularly inmechanical and electromechanical computing and sorters assigned. It lasted however until 1928 before the punch card their final, standardized format got (that by the way, as occasionally states, the size of in dollar light at that time does not correspond). After its inventor was for this kind punch cardsalso the designation Hollerithkarte usually.

Lochkarte
Punch card

a Hollerith punch card is a rectangular, about 18.7 cm × 8.3 cm large piece 0.17 mm thin cardboard into into given positions in columns holes to be punched around a consequence of indications (today one becamesay: to code a line text).

As in 20. Century computer, offered themselves the punch cards already established were developed as medium for the program input and data storage. Already Konrad Zuses of first computers, the Z1, became by code,consisting into a paper tape of a 35-mm-Film punched, one steered. Later for computers however almost exclusively punch cards were used after Hollerith.

The original code format for Hollerith punch cards planned only 240 positions for holes, it became however soon on 45Columns with ever 12 positions extends. This corresponded to 45 indications to 12 bits later each to store (a 6-bit coding invented it permitted 90 indications). IBM could be patented 1928 a 80-splitting format with rectangular holes, that the furthestSpreading found and also this very day with large computer plants from IBM to to find is; to today usual maximum line length of scarcely 80 indications in enamels and text files decreases/goes back to this punch card format. Into the punch card can in 80 columns andin 12 lines of holes to be punched. Originally only one hole per column could be used for numbers. Later a second punching for capital letters and a third punching for special characters were added. With use of EBCDIC-CODE since 1964 became up to6-fach punchings certified. A map corresponded to a line text and a column a map of an indication position of the line. A punch card had thus a capacity of approximately 80 byte. Today usual 80 GB a non removable disk knows thus contentsa billion store punch cards. That would correspond to a punch card deck of 170 km height.

The firm adjustment at the columns of the punch cards had effect on the syntax of some programming languages. With old FORTRAN - variants were the first five columns for a numeric Label intended. With brisk examination of the punch cards could be very simply recognized, if a label or the source code were wrongly positioned. Any indication in column 6 meant: Continuation map, i.e. the instruction on the previous punch card/line becomes starting from column 7continued. The eight columns 73 to 80 were reserved with FORTRAN for comments. Here one often punched a sequential number, so that one could sort a fallen down punch card deck more easily. The programming language COBOL is based with its language syntax likewise on the punch card. Alsothe data cards had normally a firm format, whereby a data record corresponded there to a map and the input data were assigned as for example to amount, customer number and date firm ranges of the columns.

Numerous improvements of the punch card systems go on Gustav Tauschek (1899 -1945) back.

to describe

function around punch cards and/or. to punch, there was card punch. These devices had a typewriter keyboard, a feeding device for the punch cards and a program card. On the card punch the data became into the punch cardpunched and as a check on a second machine, the Kartenprüfer again entered. If the punchings agreed, the map was marked as examined. For the simplification and acceleration the program card served the work. There z could. B. on the map of fields asnumerically or alphanumerically to be defined. To these fields could be jumped directly. Also there was copying branch, with which the straight punched map up to a desired column could be copied. This function became later from operating systems with terminal-controlled inputto spend taken over around an edited line on a teleprinter or later also a monitor again. The line entered last knows this very day z. B. during the Windows request for input character by character by the cursor right key to be copied.

Card punches could to the data output of programs howPrinter to be headed for. Newer devices printed with additionally to the punched code contents than plain language on the maps, experienced programmers could the punch cards even without further aids, simply only by view of the hole positions, read.

Lochkartenstanzer von IBM
Card punches were read in by

IBM thosePunch cards by optical or mechanical readers. The punch card deck was inserted into a read subject and weighted with a weight. On push of a button the equipment was turned on. The pile was loosened up by a blower and a map after the other one was read in. ThatReading took place either via mechanical scanning with pins or via light barriers with photoelectric cells.

The programs at that time were not interactive; a program was started, read input data, processed it and gave certain result data. This function caused three sentencesof punch cards: A sentence for the input data, a sentence for the processing program, and a set of output data, which was produced by the program by the processing of the input data and spent by punching devices. Punching punch cards as result data represented the exception.Usually a printout of the results was enough, and with introduction of magnetic plate storages, which had the size of washing machines around 1980 in the large computer world about, intermediate results could be also stored. It was also possible, those with introduction of the first line terminals likewise importedTo serve line editors with punch cards and to change thus stored programs; an art, which controlled above all students in the hopelessly overflowed terminals of the universities. The English name for a card deck is batch and the whole process of the processing as well asalso the program pile was a job. From this the terms batch job , batch file and also the file dung became asked for DOS - a batch file.

later history

the introduction of magnetic tapes than quick and transportable mass storages displaced, beginning centerthe 1960er years, slowly the punch card as storage medium for computers. A smaller map of higher capacity introduced into the late 1960er years of IBM could not intersperse itself any longer.

Punch card systems found other ranges of application because of their robustness in addition, so for examplefor key maps and badges. The punch cards were partly welded thereby into transparent or translucent plastic. Meanwhile also these punch cards were replaced again to a large extent by smart cards and similar systems.

There are today still punch cards in the Hollerith format with some mechanical Stempeluhren. They find also still in US-American choice automat use, their reliability however with the choice of George W. Bush to the president of the USA is strongly into the criticism guessed/advised. In the computer engineering are not material punch cards nowadays any longer of importance.However still frequently opinion poll data in files is stored, whose format at punch cards is angeleht -- also in 21. Century gives it thus still to “columns” and “maps”, even if only virtually (see:List of the terms and methods of the market study, Quantity).

A historical side remark: The company Tabulating Machine company created by Hollerith was renamed later in IBM.

see also

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