Punched tape
Punched tape or perforated paper tape is a form of data storage device that consists of a long strip of paper through which small holes are punched. It was developed from and was subsequently used alongside punched cards, the difference being that the tape is continuous.
Punched cards, and chains of punched cards, were used for control of looms in the 18th century. Use for telegraphy systems started in 1842. Punched tapes were used throughout the 19th and for much of the 20th centuries for programmable looms, teleprinter communication, for input to computers of the 1950s and 1960s, and later as a storage medium for minicomputers and CNC machine tools. During the Second World War, high-speed punched tape systems using optical readout methods were used in code breaking systems. Punched tape was used to transmit data for manufacture of read-only memory chips.
History
Perforated paper tapes were first used by
In 1842, a French patent by Claude Seytre described a piano playing device that read data from perforated paper rolls. By 1900, wide perforated music rolls for player pianos were used to distribute popular music to mass markets.
In 1846,
In the 1880s,
Modern use
In the 21st century, punched tape is obsolete except among hobbyists. In computer numerical control (CNC) machining applications, though paper tape has been superseded by digital memory, some modern systems still measure the size of stored CNC programs in feet or meters, corresponding to the equivalent length if the data were actually punched on paper tape.[3]
Formats
Data was represented by the presence or absence of a hole at a particular location. Tapes originally had five rows of holes for data across the width of the tape. Later tapes had more rows. A 1944 electro-mechanical programmable calculating machine, the Automatic Sequence Controlled Calculator or
A row of smaller sprocket holes was always punched to be used to synchronize tape movement. Originally, this was done using a wheel with radial teeth called a
Materials
Many early machines used oiled paper tape, which was pre-impregnated with a light
For heavy-duty or repetitive use, polyester
Dimensions
Tape for punching was usually 0.00394 inches (0.100 mm) thick. The two most common widths were 11⁄16 inch (17 mm) for five bit codes, and 1 inch (25 mm) for tapes with six or more bits. Hole spacing was 0.1 inches (2.5 mm) in both directions. Data holes were 0.072 inches (1.8 mm) in diameter; sprocket feed holes were 0.046 inches (1.2 mm).[6]
Chadless tape
Most tape-punching equipment used solid circular 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 containment and to interfere with the other electromechanical parts of the teleprinter equipment. Chad from oiled paper tape was particularly problematic, as it tended to clump and build up, rather than flowing freely into a collection container.
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 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. 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 technology was that, once punched, chadless tape did not roll up well for storage, because the protruding flaps of paper would catch on the next layer of tape so it could not be coiled up tightly. Another disadvantage that emerged in time, was that there was no reliable way to read chadless tape in later high-speed readers which used optical sensing. However, the mechanical tape readers used in most standard-speed equipment had no problem with chadless tape, because they sensed the holes by means of blunt spring-loaded mechanical sensing pins, which easily pushed the paper flaps out of the way.
Encoding
Text was encoded in several ways. The earliest standard
Applications
Communications
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 "off-line" at the operator's 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 75 WPM, but it operated continuously. By preparing the tape "off-line" and then sending the message with a tape reader, the line could operate continuously rather than depending on continuous "on-line" typing by a single operator. Typically, a single 75 WPM 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 1,000 characters per second.[8] In 1963, a Danish company called Regnecentralen introduced a paper tape reader called RC 2000 that could read 2,000 characters per second; later they increased the speed further, up to 2,500 cps. As early as World War II, the Heath Robinson tape reader, used by Allied codebreakers, was capable of 2,000 cps while Colossus could run at 5,000 cps using an optical tape reader designed by Arnold Lynch.
Minicomputers
When the first
Computer-aided manufacturing
In the 1970s,
Premium black waxed and lubricated long-fiber papers, and
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 mask-programmable read-only memory (ROM) chips or their erasable counterparts EPROMs. A significant variety of encoding formats were developed for use in computer and ROM/EPROM data transfer.[9] 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 proprietary formats.
A much more primitive as well as a much longer high-level encoding scheme was also used,
Cash registers
Newspaper industry
Punched paper tape was used by the newspaper industry until the mid-1970s or later. Newspapers were typically set in hot lead by devices like Linotype machines. With the wire services coming into a device that would punch paper tape, rather than the Linotype operator having to retype all the incoming 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 re-typing 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 Linotype and hot lead typesetting, many early phototypesetter devices utilized paper tape readers.
If an error was found at one position on the six-level tape, that character could be turned into a null character to be skipped by punching out the remaining non-punched 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.
Cryptography
Advantages and limitations
Acid-free paper or Mylar tapes can be read many decades after manufacture, in contrast with magnetic tape that can deteriorate and become unreadable with time. The hole patterns of punched tape can be decoded by eye if necessary, and even editing of a tape is possible by manual cutting and splicing. Unlike magnetic tape, magnetic fields such as produced by electric motors cannot alter the punched data.[15] In cryptography applications, a punched tape used to distribute a key can be rapidly and completely destroyed by burning, preventing the key from falling into the hands of an enemy.
Reliability of paper tape punching operations was a concern, so that for critical applications a new punched tape could be read after punching to verify the correct contents. Rewinding a tape required a takeup reel or other measures to avoid tearing or tangling the tape. [citation needed] In some uses, "fan fold" tape simplified handling as the tape would refold into a "takeup tank" ready to be re-read. The information density of punched tape was low compared with magnetic tape, making large datasets clumsy to handle in punched tape form.
Gallery
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The 1943 Colossus code-breaking machine used paper tapes to hold data (replica shown)
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This 1959 IBM 1620 relied on paper tape to store data and programs
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Tape reader used with aUS Census
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A large-capacity industrial tape reader
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This early-1960s Monrobot XI computer used two paper tape reader/punches for offline data storage
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Fanfold paper tape reader on a PDP-1 minicomputer (1960s)
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Paper tape readers for a word-processing system, c. 1970
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Large IBM 1130 systems still handled paper tape in the early 1970s (at left of console)
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Eight-hole tape from 1974
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This 1970s DEC high-speed fanfold reader/punch used optical sensing
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Paper tape loop controlling paper positioning in a IBM 1403 line printer (1959-1983)
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Late-1970s heavy-duty tape punch used by the US National Security Agency for secret code distribution
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Punch tape as an element of facade mosaic, Novosibirsk
See also
References
- ^ Maxfield, Clive (2011-10-13). "How it was: Paper tapes and punched cards". EE Times.
- ^ Roberts, Steven. "3. Cooke and Wheatstone". Distant Writing: A History of the Telegraph Companies in Britain between 1838 and 1868.
- ISBN 978-0-8311-3350-4.
- ^ Dalakov, Georgi, History of computers: The MARK computers of Howard Aiken, retrieved 2011-01-12
- ^ "CSIRAC paper tape (replica)". Computer History Museum. 2010. Retrieved 2023-10-13.
- ^ Lancaster, Don (2010), TV Typewriter Cookbook (PDF), Synergetics SP Press, p. 211
- ISBN 978-3837045734.
- S2CID 61020497
- ^ "Translation File Formats" (PDF). Data I/O Corporation. Retrieved 2010-08-30.
- ^ a b "Appendix A: A Sample Program in PL/M: BNPF Object Tape". MCS-8 A Guide to PL/M programming (PDF). Rev 1 (printed September 1974 ed.). 1974-03-15 [September 1973]. p. 101. MCS180-0774-1K, MCS280-0974-1K. Archived (PDF) from the original on 2022-01-29. Retrieved 2022-05-18. (1+i+100+1+11+1 pages)
- ^ ISBN 3-7723-8022-0. (NB. The book contains a description of the BNPF format.)
- ^ (NB. This manual describes a "BPNF Paper Tape Format", a "Non-Intellec Hex Paper Tape Format" and a "PN Computer Punched Card Format".)
- ^ "A. Serial Data Transfer Formats: ASCII BPNF, BHLF & B10F Formats". XP640 EPROM Programmer - User Manual (PDF). GP Industrial Electronics. 1984. p. 43. Archived (PDF) from the original on 2023-10-22. Retrieved 2023-10-22. (47 pages)
- ^ "Tale of the Tape". National Security Agency Central Security Service. 2016-05-03. Archived from the original on 2021-09-23. Retrieved 2014-06-16.
- ISBN 978-90-277-2287-4.
External links
- "ECMA standard for Data Interchange on Punched Tape". European Computer Manufacturers Association. November 1965. ECMA-10. Archived from the original on 2011-09-27. Retrieved 2003-07-10.
- A song mentioning paper tape
- Various punched media
- Olympia Flexowriter
- Detailed description of two paper tape code systems, Baudot code and the system used by the ILLIAC computer
- Working paper tape punch/reader GNT 3601, Musée Bolo, YouTube