By not fully punching out the hole, the printing on the paper remained intact and legible. 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. This machine would punch a received teleprinter signal into tape and print the message on it at the same time, using a printing mechanism similar to that of an ordinary page printer. Managing the disposal of chad was an annoying and complex problem, as the tiny paper pieces had a tendency to escape and interfere with the other electromechanical parts of the teleprinter equipment.Ī variation on the tape punch was a device called a Chadless Printing Reperforator. This process created "chad", or small circular pieces of paper. Most tape-punching equipment used solid punches to create holes in the tape. Chadless tapeĬhadless 5-level Baudot paper tape circa ~1975–1980 punched at Teletype Corp Data holes were 0.072 inches (1.83 mm) in diameter feed holes were 0.046 inches (1.17 mm). Hole spacing was 0.1 inch (2.54 mm) in both directions. The two most common widths were 11/16 inch (17.46 mm) for five bit codes, and 1 inch (25.4 mm) for tapes with six or more bits. Tape for punching was 0.00394 inches (0.1 mm) thick. The bits on the narrower side of the tape are generally the least significant bits, when the code is represented as numbers in a digital system. The sprocket holes are slightly to one side, making it clear which way to orient the tape in the reader and dividing the tape into unequal sides. Later optical readers used the sprocket holes to generate timing pulses. A row of smaller sprocket holes that were always punched served to feed the tape, originally using a wheel with radial teeth called a sprocket wheel. An early electro-mechanical programmable calculating machine, the Automatic Sequence Controlled Calculator or Harvard Mark I, used paper tape with 24 rows. Later tapes had six, seven and eight rows. Tapes originally had five rows of holes for data. ĭata was represented by the presence or absence of a hole at a particular location. However, some modern CNC systems still measure the size of stored CNC programs in feet or meters, corresponding to the equivalent length if punched on paper tape. In computer numerical control (CNC) machining applications, very few people still use tape. It may still be used in older military systems and by some hobbyists. In the 21st century, use of punched tape is very rare. The system went into commercial use in 1897 and was in production well into the 1970s, undergoing several changes along the way. The tape reader used compressed air, which passed through the holes and was directed into certain mechanisms of the caster. The tape, punched with the keyboard, was later read by the caster, which produced lead type according to the combinations of holes in 0, 1, or more of 31 positions. In 1880s, Tolbert Lanston invented the Monotype System, which consisted of a keyboard (typesetting machine) and a composition caster. This technology was adopted by Charles Wheatstone in 1857 for the preparation, storage and transmission of data in telegraphy. In 1846, Alexander Bain used punched tape to send telegrams. In 1842, a French patent by Claude Seytre described a piano playing device that read data from perforated paper rolls. Many professional embroidery operations still refer to those individuals who create the designs and machine patterns as "punchers" even though punched cards and paper tape were eventually phased out in the 1990s. This led to the concept of communicating data not as a stream of individual cards, but as one "continuous card" (or tape). The resulting paper tape, also called a "chain of cards", was stronger and simpler both to create and to repair. By 1801, Joseph Marie Jacquard had developed machines to create paper tapes by tying punched cards in a sequence for Jacquard looms. However, the paper tapes were expensive to create, fragile, and difficult to repair. Perforated paper tapes were first used by Basile Bouchon in 1725 to control looms. Paper tapes constructed from punched cards were widely used throughout the 19th century for controlling looms. The large holes on each edge are sprocket holes, used to pull the paper tape through the loom. A paper tape, constructed from punched cards, in use in a Jacquard loom.
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