Punched tape
Encyclopedia
Punched tape or paper tape is an obsolete form of data storage
, consisting of a long strip of paper in which holes are punched to store data. 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 minicomputer
s and CNC machine tools.
looms and embroidery, where cards with simple instructions about a machine's intended movements were first fed individually as instructions, then controlled by instruction cards, and later were fed as a string of connected cards. (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.
holes that were always punched served to feed the tape, typically with a wheel with radial teeth called a sprocket wheel. An early electro-mechanical calculating machine, the Automatic Sequence Controlled Calculator or Harvard Mark I
, used paper tape with 24 rows. Text was encoded in several ways. The earliest standard character encoding
was Baudot
, which dates back to the nineteenth century and had 5 holes. Later standards, such as Teletypesetter (TTS), Fieldata
and Flexowriter, had 6 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 7-level code was adopted by some teleprinter users, including AT&T
(Teletype). Others, such as Telex
, stayed with Baudot.
", or small circular pieces of paper. Managing the disposal of chad was an annoying and complex problem, as the tiny paper pieces had a distressing tendency to escape and interfere with the other electromechanical parts of the teleprinter equipment.
One 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, of course, 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 high-speed readers. However, the mechanical tape readers used in most standard-speed equipment had no problem with chadless tape, because it sensed the holes by means of blunt spring-loaded sensing pins, which easily pushed the paper flaps out of the way.
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 135WPM (Words Per Minute) or more for short periods.
The line typically operated at 75WPM, 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 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.
When the first minicomputer
s were being released, most manufacturers turned to the existing mass-produced ASCII teleprinter
s (primarily the ASR33
capable of 10 ASCII
characters per second throughput) as a low-cost solution for keyboard input and printer output. The commonly specified Model 33 ASR included a paper tape punch/reader, where ASR stands for "Automatic Send/Receive" as opposed to the punchless/readerless KSR - Keyboard Send/Receive
and ROP - Receive Only Printer 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 minicomputer
s was often accomplished using a doubly encoded technique to compensate for the relatively high error rate of punches / readers. The low-level 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 35-40% (e.g., 36% from 44 8-bit ASCII
characters being needed to represent 16 byte
s of binary data per frame).
chips or their erasable counterparts - EPROM
s.
A significant variety of encoding formats were developed for use in computer and ROM/EPROM 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 computer-proprietary formats.
A much more primitive as well as a much longer high-level encoding scheme was also used - BNPF (Begin-Negative-Positive-Finish). 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 a ending ASCII
"F". These ten-character ASCII
sequences were separated by one or more whitespace characters, therefore using at least 11 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 "H" and "L" or "0" and "1" were also available to represent data bits, but in both of these encoding schemes, the two data-bearing ASCII
characters differ in only one bit position, providing very poor single punch error detection.
(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.
. 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 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 the Linotype/hot lead, many early "offset" devices had paper tape readers on them to produce the news-story copy.
equipment often used paper tape. Paper tape was a very important storage medium for computer-controlled wire-wrap 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 long-fiber papers, and Mylar film
tape were invented so that production tapes for these machines would last longer.
used punched paper tape to distribute cryptographic keys
. The 8-level paper tapes were distributed under strict accounting controls and were read by a fill device
, such as the hand held KOI-18
, 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 paper tape is apparently still being employed.
in Moscow (1964) holds what appears to be a punched tape with three rows of rectangular holes.
Data storage device
thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....
, consisting of a long strip of paper in which holes are punched to store data. It was widely used during much of the twentieth century for teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
communication, for input to computers of the 1950s and 1960s, and later as a storage medium for minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s and CNC machine tools.
Origin
The earliest forms of punched tape come from weavingWeaving
Weaving is a method of fabric production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric or cloth. The other methods are knitting, lace making and felting. The longitudinal threads are called the warp and the lateral threads are the weft or filling...
looms and embroidery, where cards with simple instructions about a machine's intended movements were first fed individually as instructions, then controlled by instruction cards, and later were fed as a string of connected cards. (See Jacquard loom
Jacquard loom
The Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, that simplifies the process of manufacturing textiles with complex patterns such as brocade, damask and matelasse. The loom is controlled by punched cards with punched holes, each row of which corresponds to one row...
).
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
Alexander Bain (inventor)
Alexander Bain was a Scottish inventor and engineer who was first to invent and patent the electric clock. Bain installed the railway telegraph lines between Edinburgh and Glasgow.-Early life:...
used punched tape to send telegrams.
Tape formats
Data was represented by the presence or absence of a hole in a particular location. Tapes originally had five rows of holes for data. Later tapes had 6, 7 and 8 rows. A row of narrower sprocketSprocket
A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which are radial projections that engage a chain passing over it...
holes that were always punched served to feed the tape, typically with a wheel with radial teeth called a sprocket wheel. An early electro-mechanical calculating machine, the Automatic Sequence Controlled Calculator or Harvard Mark I
Harvard Mark I
The IBM Automatic Sequence Controlled Calculator , called the Mark I by Harvard University, was an electro-mechanical computer....
, used paper tape with 24 rows. Text was encoded in several ways. The earliest standard character encoding
Character encoding
A character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in...
was Baudot
Baudot code
The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...
, which dates back to the nineteenth century and had 5 holes. Later standards, such as Teletypesetter (TTS), Fieldata
Fieldata
Fieldata was a pioneering computer project run by the US Army Signal Corps in the late 1950s that intended to create a single standard for collecting and distributing battlefield information...
and Flexowriter, had 6 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
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
. This 7-level code was adopted by some teleprinter users, including AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
(Teletype). Others, such as Telex
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
, stayed with Baudot.
Chadless Tape
Most tape-punching equipment used solid punches to create holes in the tape. This process inevitably creates "chadChad (paper)
Chad refers to paper fragments created when holes are made in a paper, card or similar synthetic materials, typically computer punched tape or punched cards. Sometimes chad has been used as a mass noun or as a countable noun, and the plural is commonly either "chad" or "chads"...
", or small circular pieces of paper. Managing the disposal of chad was an annoying and complex problem, as the tiny paper pieces had a distressing tendency to escape and interfere with the other electromechanical parts of the teleprinter equipment.
One 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
Chad (paper)
Chad refers to paper fragments created when holes are made in a paper, card or similar synthetic materials, typically computer punched tape or punched cards. Sometimes chad has been used as a mass noun or as a countable noun, and the plural is commonly either "chad" or "chads"...
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, of course, 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 high-speed readers. However, the mechanical tape readers used in most standard-speed equipment had no problem with chadless tape, because it sensed the holes by means of blunt spring-loaded sensing pins, which easily pushed the paper flaps out of the way.
Communications
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
. 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 135WPM (Words Per Minute) or more for short periods.
The line typically operated at 75WPM, 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 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
Store and forward
Store and forward is a telecommunications technique in which information is sent to an intermediate station where it is kept and sent at a later time to the final destination or to another intermediate station. The intermediate station, or node in a networking context, verifies the integrity of...
networks were developed using these techniques.
Paper tape could be read into computers at up to 1000 characters per second.
Minicomputers
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s were being released, most manufacturers turned to the existing mass-produced ASCII teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
s (primarily the ASR33
ASR33
The Teletype Model ASR-33 was a very popular model of teleprinter. Introduced about 1963 by Teletype Corporation and designed for light-duty office use, it was less rugged and less expensive than earlier Teletype machines or its heavy-duty cousin, the Model 35-ASR.The Model 33's printing mechanism...
capable of 10 ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
characters per second throughput) as a low-cost solution for keyboard input and printer output. The commonly specified Model 33 ASR included a paper tape punch/reader, where ASR stands for "Automatic Send/Receive" as opposed to the punchless/readerless KSR - Keyboard Send/Receive
Keyboard Send Receive
Keyboard send receive is part of a designation for a series of hard-copy teleprinters, manufactured by Teletype Corporation. The KSR range were lower cost versions of the ASR models. These models included, but were not limited to the Model 28 KSR, the Model 32 KSR, the Model 33 KSR and the Model...
and ROP - Receive Only Printer 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 minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s was often accomplished using a doubly encoded technique to compensate for the relatively high error rate of punches / readers. The low-level encoding was typically ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
, further encoded and framed in various schemes such as Intel Hex
Intel HEX
Intel HEX is a file format for conveying binary information for applications like programming microcontrollers, EPROMs, and other kinds of chips. It is one of the oldest file formats available for this purpose, having been in use since the 1970s...
- 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 35-40% (e.g., 36% from 44 8-bit ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
characters being needed to represent 16 byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
s 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 mask-programmable read-only memory (ROM)Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
chips or their erasable counterparts - EPROM
EPROM
An EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
s.
A significant variety of encoding formats were developed for use in computer and ROM/EPROM data transfer. Encoding formats commonly used were primarily driven by those formats that EPROM programming devices supported and included various ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
hex variants as well as a number of computer-proprietary formats.
A much more primitive as well as a much longer high-level encoding scheme was also used - BNPF (Begin-Negative-Positive-Finish). In BNPF encoding, a single byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
(8 bits) would be represented by a highly redundant character framing sequence starting with a single ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
"B", eight ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
characters where a "0" would be represented by a "N" and a "1" would be represented by a "P", followed by a ending ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
"F". These ten-character ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
sequences were separated by one or more whitespace characters, therefore using at least 11 ASCII characters for each byte stored (9% efficiency). The ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
"N" and "P" characters differ in four bit positions, providing excellent protection from single punch errors. Alternative schemes were also available where "H" and "L" or "0" and "1" were also available to represent data bits, but in both of these encoding schemes, the two data-bearing ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
characters differ in only one bit position, providing very poor single punch error detection.
Cash registers
National Cash Register or NCRNCR Corporation
NCR Corporation is an American technology company specializing in kiosk products for the retail, financial, travel, healthcare, food service, entertainment, gaming and public sector industries. Its main products are self-service kiosks, point-of-sale terminals, automated teller machines, check...
(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 mid-1970's or later. Newspapers were typically set in hot lead by devices such as a linotypeLinotype
The Mergenthaler Linotype Company is a corporation founded in the United States in 1886 to market the linecaster invented by Ottmar Mergenthaler...
. 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 re-typing the stories. This also allowed newspapers to use devices, such as the Friden Flexowriter
Friden Flexowriter
The Friden Flexowriter was a teleprinter, a heavy duty electric typewriter capable of being driven not only by a human typing, but also automatically by several methods including direct attachment to a computer and by use of paper tape....
, to convert typing to lead type via tape. Even after the demise of the Linotype/hot lead, many early "offset" devices had paper tape readers on them to produce the news-story copy.
Automated machinery
In the 1970s, computer-aided manufacturingComputer-aided manufacturing
Computer-aided manufacturing is the use of computer software to control machine tools and related machinery in the manufacturing of workpieces. This is not the only definition for CAM, but it is the most common; CAM may also refer to the use of a computer to assist in all operations of a...
equipment often used paper tape. Paper tape was a very important storage medium for computer-controlled wire-wrap machines, for example. A paper tape reader was smaller and much less expensive than hollerith card or magnetic tape
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
readers. Premium black waxed and lubricated long-fiber papers, and Mylar film
PET film (biaxially oriented)
BoPET is a polyester film made from stretched polyethylene terephthalate and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation.A variety of companies manufacture boPET and other...
tape were invented so that production tapes for these machines would last longer.
Cryptography
Paper tape was the basis of the Vernam cipher, invented in 1917. During the last third of the 20th century, the U.S. National Security AgencyNational Security Agency
The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States Department of Defense responsible for the collection and analysis of foreign communications and foreign signals intelligence, as well as protecting U.S...
used punched paper tape to distribute cryptographic keys
Key (cryptography)
In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would produce no useful result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa...
. The 8-level paper tapes were distributed under strict accounting controls and were read by a fill device
Fill device
A fill device is an electronic module used to load cryptographic keys into electronic encryption machines. Fill devices are usually hand held and battery operated....
, such as the hand held KOI-18
KOI-18
The KOI-18 is a hand-held paper tape reader developed by the U.S. National Security Agency as a fill device for loading cryptographic keys, or "crypto variables," into security devices, such as encryption systems. It can read 8-level paper or PET tape, which is manually pulled through the reader...
, 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
EKMS
The Electronic Key Management System system is a United States National Security Agency led program responsible for Communications Security key management, accounting and distribution...
), but paper tape is apparently still being employed.
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 hole by hole 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 tapeMagnetic tapeMagnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
s 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 acid-free paperAcid-free paperAcid-free paper is paper that has a neutral or basic pH . It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin and sulfur free...
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 all-hole 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 controlNumerical controlNumerical control refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone...
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 was loaded into the device, or if it may fall into enemy hands, the paper tape was simply burned.
Punched tape in art
A computing or telecommunications professional depicted in the Monument to the Conquerors of SpaceMonument to the Conquerors of Space
The Monument to the Conquerors of Space was erected in Moscow in 1964 to celebrate achievements of the Soviet people in space exploration. It depicts a starting rocket that rises on its contrail. The monument is 110 m tall, has 77° incline, and is made of titanium...
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 rare to nonexistent. No systems built new today still use punched paper tape. In CNC machining applications, what few existing installations remained in grandfathered use are now quickly disappearing as the temporary advantages for new orders of old part designs (i.e., not rewriting programs or retooling machines) are being washed away by natural economic evolution (fewer such orders as decades go by; part design revisions required reprogramming anyway; newer, higher-capability machines now successfully poaching the orders; etc.).See also
- Bit bucketBit bucketIn computing, the bit bucket is jargon for where lost computerized data has gone, by any means; any data which does not end up where it is supposed to, being lost in transmission, a computer crash, or the like, is said to have gone to the bit bucket — that mysterious place on a computer where...
- Book musicBook musicBook Music is a medium for storing the music played on mechanical organs, mainly of European manufacture. Book music is made from thick cardboard, containing perforated holes representing the musical notes to be played, with the book folded zig-zag style...
- ChadChad (paper)Chad refers to paper fragments created when holes are made in a paper, card or similar synthetic materials, typically computer punched tape or punched cards. Sometimes chad has been used as a mass noun or as a countable noun, and the plural is commonly either "chad" or "chads"...
(the little pieces of paper punched out of the tape). - Jacquard loomJacquard loomThe Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, that simplifies the process of manufacturing textiles with complex patterns such as brocade, damask and matelasse. The loom is controlled by punched cards with punched holes, each row of which corresponds to one row...
Controlled by a system similar to, but not quite the same as punched tape. - Key punchKey punchA keypunch is a device for manually entering data into punched cards by precisely punching holes at locations designated by the keys struck by the operator. Early keypunches were manual devices. Later keypunches were mechanized, often resembled a small desk, with a keyboard similar to a...
- Music rollMusic rollA music roll is a storage medium used to operate a mechanical musical instrument. They are used for the player piano, mechanical organ, electronic carillon and various types of orchestrion. The vast majority of music rolls are made of paper...
- Piano rollPiano rollA piano roll is a music storage medium used to operate a player piano, piano player or reproducing piano. A piano roll is a continuous roll of paper with perforations punched into it. The peforations represent note control data...
- Punched cardPunched cardA punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions...
- Zygalski sheets - a system used to decrypt messages enciphered on German EnigmaEnigma machineAn Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
machines.
External links
- ECMA-10: ECMA standard for Data Interchange on Punched Tape
- 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 FridenFriden, Inc.Friden Calculating Machine Company was an American manufacturer of typewriters and electronic calculators. It was founded by Carl Friden in San Leandro, California in 1934. Friden electromechanical calculators were robust and popular....
in the late 1950s (Retrieved April 10, 2007) - Olympia Flexowriter
- Detailed description of two paper tape code systems, Baudot codeBaudot codeThe Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...
and the system used by the ILLIACILLIACILLIAC was a series of supercomputers built at a variety of locations, some at the University of Illinois at Urbana-Champaign. In all, five computers were built in this series between 1951 and 1974...
computer