punched tape fivehole and eighthole punched paper tape paper tape reader on an early computer with a small piece of fivehole tape connected in a circle creating a physical program loop punched tape or perforated paper tape is a form of data storage consisting of a long strip of paper in which holes are punched to store data now effectively obsolete it was widely used during much of the twentieth century for teleprinter communication for input to computers of the 1950s and 1960s and later as a storage medium for minicomputers and cnc machine tools origin a paper tape constructed from punched cards in use in a jacquard loom the large holes on each edge are sprocket holes used to pull the paper tape through the loom paper tapes constructed from punched cards were widely used throughout the 19th century for controlling looms perforated paper tapes were first used by basile bouchon in 1725 to control looms however the paper tapes were expensive to create fragile and difficult to repair by 1801 joseph marie jacquard had developed machines to create paper tapes by tying punched cards in a sequence the resulting paper tape also called a chain of cards was stronger and simpler both to create and to repair see jacquard loom this led to the concept of communicating data not as a stream of individual cards but one continuous card or a tape 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 after many years of use in the 1990s 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 in 1857 charles wheatstone used paper tape for the preparation storage and transmission of data in telegraphy in 1880s tolbert lanston invented the monotype system which consisted of a keyboard typesetting machine and a composition 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 one or more of 31 positions the tape reader used compressed air which passed through the holes and was directed into certain mechanisms of the caster the system went into commercial use in 1897 and was in production well into the 1970s undergoing several changes along the way tape formats a 24channel program tape for the harvard mark i data were represented by the presence or absence of a hole at a particular location tapes originally had five rows of holes for data later tapes had six seven and eight rows an early electromechanical calculating machine the automatic sequence controlled calculator or harvard mark i used paper tape with twentyfour rows text was encoded in several ways the earliest standard character encoding was baudot which dates back to the nineteenth century and had five holes the baudot code was never used in teleprinters instead modifications such as the murray code which added carriage return and line feed western union code international telegraph alphabet no 2 ita 2 and american teletypewriter code ustty were used other standards such as teletypesetter tts fieldata and flexowriter had six holes in the early 1960s the american standards association led a project to develop a universal code for data processing which became known as ascii this sevenlevel code was adopted by some teleprinter users including att teletype others such as telex stayed with the earlier codes dimensions tape for punching was 000394 inches 01mm thick the two most common widths were 1116 inch 1746mm for five bit codes and 1 inch 254mm for tapes with six or more bits hole spacing was 01 inch 254mm in both directions data holes were 0072 inches 183mm in diameter feed holes were 0046 inches 117mm chadless tape most tapepunching equipment used solid punches to create holes in the tape this process created chad or small circular pieces of paper 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 chadless 5level baudot paper tape circa 19751980 punched at teletype corp a variation on the tape punch was a device called a chadless printing reperforator 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 the tape punch rather than punching out the usual round holes would instead punch little ushaped cuts in the paper so that no chad would be produced the hole was still filled with a little paper trapdoor by not fully punching out the hole the printing on the paper remained intact and legible this enabled operators to read the tape without having to decipher the holes which would facilitate relaying the message on to another station in the network also there was no chad box to empty from time to time a disadvantage to this mechanism was that chadless tape once punched did not roll up well because the protruding flaps of paper would catch on the next layer of tape so it could not be rolled up tightly another disadvantage as seen over time was that there was no reliable way to read chadless tape by optical means employed by later highspeed readers however the mechanical tape readers used in most standardspeed equipment had no problem with chadless tape because it sensed the holes by means of blunt springloaded sensing pins which easily pushed the paper flaps out of the way the word wikipedia and a crlf as 7bit ascii without a parity bit least significant bit on the right eg w is 1010111 applications communications paper tape relay operation at us faas honolulu flight service station in 1964 punched tape was used as a way of storing messages for teletypewriters operators typed in the message to the paper tape and then sent the message at the maximum line speed from the tape this permitted the operator to prepare the message offline at the operators best typing speed and permitted the operator to correct any error prior to transmission an experienced operator could prepare a message at 135 words per minute wpm or more for short periods the line typically operated at 75wpm but it operated continuously by preparing the tape offline and then sending the message with a tape reader the line could operate continuously rather than depending on continuous online typing by a single operator typically a single 75wpm line supported three or more teletype operators working offline tapes punched at the receiving end could be used to relay messages to another station large store and forward networks were developed using these techniques paper tape could be read into computers at up to 1000 characters per second the danish company regnecentralen developed a paper tape reader called rc 2000 that could read 2000 characters per second it was introduced in 1963 later they increased the speed further up to 2500 cps as early as world war ii the heath robinson tape reader used by allied codebreakers was capable of 2000cps while colossus could run at 5000 cps using an optical tape reader designed by dr arnold lynch minicomputers software on fanfold paper tape for the data general nova minicomputer when the first minicomputers were being released most manufacturers turned to the existing massproduced ascii teleprinters primarily the teletype model 33 capable of ten ascii characters per second throughput as a lowcost solution for keyboard input and printer output the commonly specified model 33 asr included a paper tape punchreader where asr stands for automatic sendreceive as opposed to the punchlessreaderless ksr keyboard sendreceive and ro receive only models as a side effect punched tape became a popular medium for low cost minicomputer data and program storage and it was common to find a selection of tapes containing useful programs in most minicomputer installations faster optical readers were also common binary data transfer to or from these minicomputers was often accomplished using a doubly encoded technique to compensate for the relatively high error rate of punches readers the lowlevel encoding was typically ascii further encoded and framed in various schemes such as intel hex in which a binary value of 01011010 would be represented by the ascii characters 5a framing addressing and checksum primarily in ascii hex characters information provided error detection capabilities efficiencies of such an encoding scheme are on the order of 3540 eg 36 from 44 8bit ascii characters being needed to represent sixteen bytes of binary data per frame data transfer for rom and eprom programming in the 1970s through the early 1980s paper tape was commonly used to transfer binary data for incorporation in either maskprogrammable readonly memory rom chips or their erasable counterparts eproms a significant variety of encoding formats were developed for use in computer and romeprom data transfer encoding formats commonly used were primarily driven by those formats that eprom programming devices supported and included various ascii hex variants as well as a number of computerproprietary formats a much more primitive as well as a much longer highlevel encoding scheme was also used bnpf beginnegativepositivefinish in bnpf encoding a single byte 8 bits would be represented by a highly redundant character framing sequence starting with a single ascii b eight ascii characters where a 0 would be represented by a n and a 1 would be represented by a p followed by an ending ascii f these tencharacter ascii sequences were separated by one or more whitespace characters therefore using at least eleven ascii characters for each byte stored 9 efficiency the ascii n and p characters differ in four bit positions providing excellent protection from single punch errors alternative schemes were also available where l and h or 0 and 1 were also available to represent data bits but in both of these encoding schemes the two databearing ascii characters differ in only one bit position providing very poor single punch error detection cash registers ncr of dayton ohio made cash registers around 1970 that would punch paper tape the tape could then be read into a computer and not only could sales information be summarized billings could be done on charge transactions newspaper industry punched paper tape was used by the newspaper industry until the mid1970s or later newspapers were typically set in hot lead by devices such as a linotype with the wire services coming into a device that would punch paper tape rather than the linotype operator having to retype all the incoming wire stories the paper tape could be put into a paper tape reader on the linotype and it would create the lead slugs without the operator retyping the stories this also allowed newspapers to use devices such as the friden flexowriter to convert typing to lead type via tape even after the demise of the linotypehot lead many early offset devices had paper tape readers on them to produce the newsstory copy if an error was found at one position on the sixlevel tape that character could be turned into a null character to be skipped by punching out the remaining nonpunched positions with what was known as a chicken plucker it looked like a strawberry stem remover that pressed with thumb and forefinger could punch out the remaining positions one hole at a time automated machinery paper tape reader on a computer numerical control cnc machine in the 1970s computeraided manufacturing equipment often used paper tape paper tape was a very important storage medium for computercontrolled wirewrap machines for example a paper tape reader was smaller and much less expensive than hollerith card or magnetic tape readers premium black waxed and lubricated longfiber papers and mylar film tape were invented so that production tapes for these machines would last longer cryptography vernam ciphers were invented in 1917 to encrypt teleprinter communications using a key stored on paper tape during the last third of the 20th century the national security agency used punched paper tape to distribute cryptographic keys the eightlevel paper tapes were distributed under strict accounting controls and read by a fill device such as the hand held koi18 that was temporarily connected to each security device that needed new keys nsa has been trying to replace this method with a more secure electronic key management system ekms but as of 2016 paper tape is apparently still being employed the paper tape canister is a tamper resistant container that contains features to prevent undetected alteration of the contents fanfold paper tape limitations the three biggest problems with paper tape were reliability it was common practice to follow each mechanical copying of a tape with a manual holebyhole comparison rewinding the tape was difficult and prone to problems great care was needed to avoid tearing the tape some systems used fanfold paper tape rather than rolled paper tape in these systems no rewinding was necessary nor were any fancy supply reel takeup reel or tension arm mechanisms required the tape merely fed from the supply tank through the reader to the takeup tank refolding itself back into exactly the same form as when it was fed into the reader low information density datasets much larger than a few dozen kilobytes are impractical to handle in paper tape format advantages punched tape does have some useful properties longevity although many magnetic tapes have deteriorated over time to the point that the data on them has been irretrievably lost punched tape can be read many decades later if acidfree paper or mylar film is used some paper can degrade rapidly human accessibility the hole patterns can be decoded visually if necessary and torn tape can be repaired using special allhole pattern tape splices editing text on a punched tape was achieved by literally cutting and pasting the tape with scissors glue or by taping over a section to cover all holes and making new holes using a manual hole punch magnetic field immunity in a machine shop full of powerful electric motors the numerical control programs need to survive the magnetic fields generated by those motors ease of destruction in the case of cryptographic keys the inherent flammability sometimes enhanced by using flash paper of paper tape was an asset once the key had been loaded into the device the paper tape could simply be burned preventing the key from falling into enemy hands punched tape in art a computing or telecommunications professional depicted in the monument to the conquerors of space in moscow 1964 holds what appears to be a punched tape with three rows of rectangular holes current use use of punched tape today is very rare it may still be used in older military systems bit bucket book music key punch music roll tape library zygalski sheets a system used to decrypt messages enciphered on german enigma machines wikimedia commons has media related to punched tapes ecma standard for data interchange on punched tape european computer manufacturers association november 1965 ecma10 a song mentioning paper tape various punched media friden flexowriter combination typewriter paper tape punch and paper tape reader designed by ibm during the 1940s and bought out by friden in the late 1950s retrieved april 10 2007 olympia flexowriter detailed description of two paper tape code systems baudot code and the system used by the illiac computer vtepaper data storage mediaantiquity writing on papyrus c 3000 bce paper 105 ce modern index card 1640s punched tape mid1800s punched card 1880s edgenotched card 1904 optical mark recognition 1930s barcode 1948 optical character recognition 1950s 