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An IBM 80-column punched card of the type most widely used in the 20th century IBM 1442 card reader/punch for 80 column cards. 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.
Some 2-hole punches have an "888" marking on their paper guide, to assist punching all four holes into A4 paper. [ 5 ] Konica Minolta specifies that for European 4-hole arrangements, all holes should be 11 ± 1 mm from the nearest (i.e. long/spine) edge of the paper, [ 6 ] which is slightly at variance with ISO 838's specification of 12 ± 1 mm .
To bind a document, the user first punches holes in the paper with a specialized hole punch. Pages must be punched a few at a time with most of these machines. If hard covers are desired, they must be punched as well. In bulk applications, a paper drilling machine may be used. Then the user chooses a spine size that will match the document.
The tape punch, rather than punching out the usual round holes, would instead punch little U-shaped cuts in the paper, so that no chad would be produced; the "hole" was still filled with a little paper trap-door. By not fully punching out the hole, the printing on the paper remained intact and legible.
Jacquard cards were said to be stamped or cut, rather than punched. The first Jacquard cards were stamped by hand, sometimes using a guide plate. An improvement involved placing the card between two perforated metal plates, hinged together, inserting punches according to the desired pattern, and then passing the assembly through a press to cut the card.
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. 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.
Alphabetic columns have a zone punch in rows 12, 11, or 0 and a digit punch in one of the rows 1-9, and can be sorted by passing some or all of the cards through the sorter twice on that column. For more details of punched card codes see punched card#IBM 80-column format and character codes .
Die and punch shapes affect the force during the punching process. The punch force increases during the process as the entire thickness of the material is sheared at once. A beveled punch helps in the shearing of thicker materials by reducing the force at the beginning of the stroke. However, beveling a punch will distort the shape because of ...
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