Tuesday, 12 August 2014

Punched tape

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Five-hole and eight-hole punched cardboard tape
Punched band or perforated cardboard band is a anatomy of abstracts storage, consisting of a continued band of cardboard in which holes are punched to abundance data. Now finer obsolete, it was broadly acclimated during abundant of the twentieth aeon for teleprinter communication, for ascribe to computers of the 1950s and 1960s, and after as a accumulator average for minicomputers and CNC apparatus tools.
Contents [hide]
1 Origin
2 Band formats
2.1 Dimensions
2.2 Chadless Tape
3 Applications
3.1 Communications
3.2 Minicomputers
3.3 Abstracts alteration for ROM and EPROM programming
3.4 Cash registers
3.5 Newspaper industry
3.6 Automated machinery
3.7 Cryptography
3.7.1 Cardboard band canister
4 Limitations
5 Advantages
6 Punched band in art
7 Current use
8 See also
9 References
10 External links


The earliest forms of punched tape come from weaving 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

Tape formats

Data was represented by the attendance or absence of a aperture at a accurate location. Tapes originally had 5 rows of holes for data. After tapes had 6, 7 and 8 rows. An aboriginal electro-mechanical artful machine, the Automatic Sequence Controlled Calculator or Harvard Mark I, acclimated cardboard band with 24 rows.[1] A row of narrower holes that were consistently punched served to augment the tape, originally application a caster with adorable teeth alleged a sprocket wheel. After optical readers acclimated the sprocket holes to accomplish timing pulses.
Text was encoded in several ways. The ancient accepted appearance encoding was Baudot, which dates aback to the nineteenth aeon and had 5 holes. The Baudot cipher was never acclimated in teleprinters. Instead, modifications such as the Murray cipher (which added carrying acknowledgment and band feed), Western Union code, International Telegraphic Alphabet #2 (ITA 2), and American Teletypewriter cipher (USTTY), were used.[2] Added standards, such as Teletypesetter (TTS), Fieldata and Flexowriter, had 6 holes. In the aboriginal 1960s, the American Standards Association led a activity to advance a accepted cipher for abstracts processing, which became accepted as ASCII. This 7-level cipher was adopted by some teleprinter users, including AT&T (Teletype). Others, such as Telex, backward with the beforehand codes.
Tape for punching was 0.00394 inches (0.1 mm) thick. The two a lot of accepted widths were 11/16 inch (17.46 mm) for 5 bit codes, and 1 inch (25.4 mm) for tapes with six or added bits. Aperture agreement was 0.1 inch (2.54 mm) in both directions. Abstracts holes were 0.072 inches (1.83 mm) in diameter; augment holes were 0.046 inches (1.17 mm).[3] Cardboard band rolls in both widths are still commercially accessible as of 2012.[4]
Chadless Tape[edit]
Most tape-punching accessories acclimated solid punches to actualize holes in the tape. This action accordingly created "chad", or baby annular pieces of paper. Managing the auctioning of chad was an annoying and circuitous problem, as the tiny cardboard pieces had a addiction to escape and baffle with the added electromechanical locations of the teleprinter equipment.
Chadless cardboard tape
Chadless 5-level Baudot cardboard band about ~1975-1980 punched at Teletype Corp.
One aberration on the band bite was a accessory alleged a Chadless Press Reperforator. This apparatus would bite a accustomed teleprinter arresting into band and book the bulletin on it at the aforementioned time, application a press apparatus agnate to that of an accustomed page printer. The band punch, rather than punching out the accepted annular holes, would instead bite little U-shaped cuts in the paper, so that no chad would be produced; the "hole" was still abounding with a little cardboard trap-door. By not absolutely punching out the hole, the press on the cardboard remained complete and legible. This enabled operators to apprehend the band after accepting to analyze the holes, which would facilitate relaying the bulletin on to addition base in the network. Also, of course, there was no "chad box" to abandoned from time to time. A disadvantage to this apparatus was that chadless tape, already punched, did not cycle up well, because the bulging flaps of cardboard would bolt on the next band of tape, so it could not be formed up tightly. Addition disadvantage, as apparent over time, was that there was no reliable way to apprehend chadless band by optical agency active by after accelerated readers. However, the automated band readers acclimated in a lot of standard-speed accessories had no botheration with chadless tape, because it sensed the holes by agency of edgeless spring-loaded analysis pins, which calmly pushed the cardboard flaps out of the way.



Paper band broadcast operation at US FAA's Honolulu flight account base in 1964
Punched band was acclimated as a way of autumn letters for teletypewriters. Operators typed in the bulletin to the cardboard tape, and again beatific the bulletin at the best band acceleration from the tape. This acceptable the abettor to adapt the bulletin "off-line" at the operator's best accounting speed, and acceptable the abettor to actual any absurdity above-mentioned to transmission. An able abettor could adapt a bulletin at 135WPM (words per minute) or added for abbreviate periods.
The band about operated at 75WPM, but it operated continuously. By advancing the band "off-line" and again sending the bulletin with a band reader, the band could accomplish continuously rather than depending on affiliated "on-line" accounting by a individual operator. Typically, a individual 75WPM band accurate three or added buzzer operators alive offline. Tapes punched at the accepting end could be acclimated to broadcast letters to addition station. Large abundance and advanced networks were developed application these techniques.
Paper band could be apprehend into computers at up to 1000 characters per second.[5]

Software on fanfold cardboard band for the Abstracts General Nova minicomputer.
When the aboriginal minicomputers were getting released, a lot of manufacturers angry to the absolute banal ASCII teleprinters (primarily the Buzzer Model 33, able of 10 ASCII characters per additional throughput) as a bargain band-aid for keyboard ascribe and printer output. The frequently defined Model 33 ASR included a cardboard band punch/reader, area ASR stands for "Automatic Send/Receive" as against to the punchless/readerless KSR - Keyboard Send/Receive and RO - Receive Alone models. As a ancillary effect, punched band became a accepted average for low amount minicomputer abstracts and affairs storage, and it was accepted to acquisition a alternative of tapes absolute advantageous programs in a lot of minicomputer installations. Faster optical readers were aswell common.
BINARY abstracts alteration to or from these minicomputers was generally able application a doubly encoded address to atone for the almost top absurdity amount of punches / readers. The low-level encoding was about ASCII, added encoded and affected in assorted schemes such as Intel Hex - in which a bifold amount of "01011010" would be represented by the ASCII characters "5A". Framing, acclamation and checksum (primarily in ASCII hex characters) advice provided absurdity apprehension capabilities. Efficiencies of such an encoding arrangement are on the adjustment of 35-40% (e.g., 36% from 44 8-bit ASCII characters getting bare to represent 16 bytes of bifold abstracts per frame).
Data alteration for ROM and EPROM programming[edit]
In the 1970s through the aboriginal 1980s, cardboard band was frequently acclimated to alteration bifold abstracts for assimilation in either mask-programmable read-only anamnesis (ROM) chips or their erasable counterparts - EPROMs. A cogent array of encoding formats were developed for use in computer and ROM/EPROM abstracts transfer.[6] Encoding formats frequently acclimated were primarily apprenticed by those formats that EPROM programming accessories accurate and included assorted ASCII hex variants as able-bodied as a amount of computer-proprietary formats.
A abundant added archaic as able-bodied as a abundant best high-level encoding arrangement was aswell acclimated - BNPF (Begin-Negative-Positive-Finish). In BNPF encoding, a individual byte (8 bits) would be represented by a awful bombastic appearance framing arrangement starting with a individual ASCII "B", eight ASCII characters area a "0" would be represented by a "N" and a "1" would be represented by a "P", followed by an catastrophe ASCII "F". These ten-character ASCII sequences were afar by one or added whitespace characters, accordingly application at atomic 11 ASCII characters for anniversary byte stored (9% efficiency). The ASCII "N" and "P" characters alter in four bit positions, accouterment able aegis from individual bite errors. Alternative schemes were aswell accessible area "H" and "L" or "0" and "1" were aswell accessible to represent abstracts bits, but in both of these encoding schemes, the two data-bearing ASCII characters alter in alone one bit position, accouterment actual poor individual bite absurdity detection.
Cash registers[edit]
National Banknote Register or NCR (Dayton Ohio) fabricated banknote registers about 1970 that would bite cardboard tape. The band could again be apprehend into a computer and not alone could sales advice be summarized, billings could be done on allegation transactions.
Newspaper industry[edit]
Punched cardboard band was acclimated by the bi-weekly industry until the mid-1970s or later. Newspapers were about set in hot advance by accessories such as a linotype. With the wire casework advancing into a accessory that would bite cardboard tape, rather than the linotype abettor accepting to retype all the admission wire stories, the cardboard band could be put into a cardboard band CLAIRVOYANT on the linotype and it would actualize the advance slugs afterwards the abettor re-typing the stories. This aswell accustomed newspapers to use devices, such as the Friden Flexowriter, to catechumen accounting to advance blazon via tape. Even afterwards the annihilation of the Linotype/hot lead, abounding aboriginal "offset" accessories had cardboard band readers on them to aftermath the news-story copy.
Automated machinery[edit]

Paper band CLAIRVOYANT on a computer after ascendancy (CNC) machine.
In the 1970s, computer-aided accomplishment accessories generally acclimated cardboard tape. Cardboard band was a actual important accumulator average for computer-controlled wire-wrap machines, for example. A cardboard band clairvoyant was abate and abundant beneath big-ticket than hollerith agenda or alluring band readers. Premium atramentous waxed and anointed long-fiber papers, and Mylar blur band were invented so that assembly tapes for these machines would endure longer.
Paper band was the base of the Vernam cipher, invented in 1917. During the endure third of the 20th century, the National Aegis Agency acclimated punched cardboard band to deliver cryptographic keys. The 8-level cardboard tapes were broadcast beneath austere accounting controls and were apprehend by a ample device, such as the duke captivated KOI-18, that was briefly affiliated to anniversary aegis accessory that bare new keys. NSA has been aggravating to alter this adjustment with a added defended cyberbanking key administration arrangement (EKMS), but cardboard band is allegedly still getting employed.

Fanfold cardboard tape.
Paper band canister[edit]

Paper Band Canister
The cardboard band brazier is a alter aggressive alembic from which the capacity may manually be dispensed but which prohibits reinsertion of a band already removed. It was acclimated to deeply deliver cryptographic keys. Distributing cryptographic keys in the accessible larboard the keys vulnerable. “Putting band in canisters apparent a lot of the aegis botheration by absorption the vulnerability to the point of use rather than the able time in inventory”, said Whitfield Diffie. The brazier was invented to anticipate the adeptness to alter with the cardboard band already placed central the canister. One of the primary users of the Cardboard Band Brazier was the National Aegis Agency. The NSA bare the adeptness to alteration crytographic keys in a way that cleary showed if the keys had been compromised.

paper band canister, tampered with
The cardboard band brazier to the larboard has acutely been tampered with. The cardboard band has been aloof from the brazier and an attack to reinsert the band has failed. The encrypted keys accept been disrupted; accordingly they could be biased or exploited. The cardboard band brazier has several tamper-proof architecture features:
Hugh V. Hayes, the inventor, wrote
Every cardboard band brazier is unique. This character is able during the accomplishment process, the artificial abounding into the cast creates different breeze patterns throughout the absolute cardboard band brazier thereby authoritative it absurd to alike eliminating the achievability of substitution.
Welded Seam
The anchored bond ensures that the cardboard band brazier cannot be pried accessible afterwards getting detected.
Beaded Seam
Is a different bond that is harder to alike thereby authoritative it difficult to duplicate.
Maze-like Cardboard Path
The cardboard aisle will not acquiesce the reinsertion of tape.


The three better problems with cardboard band were:
Reliability. It was accepted convenance to chase anniversary automated artful of a band with a chiral hole-by-hole comparison.
Rewinding the band was difficult and decumbent to problems. Great affliction was bare to abstain disturbing the tape. Some systems acclimated fanfold cardboard band rather than formed cardboard tape. In these systems, no rewinding was all-important nor were any adorned accumulation reel, takeup reel, or astriction arm mechanisms required; the band alone fed from the accumulation catchbasin through the CLAIRVOYANT to the takeup tank, refolding itself aback into absolutely the aforementioned anatomy as if it was fed into the reader.
Low advice density. Datasets abundant beyond than a few dozen kilobytes are abstract to handle in cardboard band format.


Punched band does accept some advantageous properties:
Longevity. Although abounding alluring tapes accept attenuated over time to the point that the abstracts on them has been irretrievably lost, punched band can be apprehend abounding decades later, if acid-free cardboard or Mylar blur is used. Some cardboard can abase rapidly.
Human accessibility. The aperture patterns can be decoded visually if necessary, and broken band can be repaired (using appropriate all-hole arrangement band splices). Editing argument on a punched band was accomplished by actually acid and pasting the band with scissors, glue, or by taping over a area to awning all holes and authoritative new holes application a chiral aperture punch.
Magnetic acreage immunity. In a apparatus boutique abounding of able electric motors, the after ascendancy programs charge to survive the alluring fields generated by those motors.[7]
Ease of destruction. In the case of cryptographic keys, the inherent flammability (sometimes added by application beam paper) of cardboard band was an asset. Once the key was loaded into the device, or if it may abatement into adversary hands, the cardboard band was artlessly burned.

Punched tape in art

A accretion or telecommunications able depicted in the Monument to the Conquerors of Space in Moscow (1964) holds what appears to be a punched band with three rows of ellipsoidal holes.

Current use

Use of punched band today is actual attenuate and is acclimated alone in aggressive systems.[citation needed] In CNC machining applications, what few absolute installations remained in grandfathered use are now bound dematerialization as the acting advantages for new orders of old allotment designs (i.e., not afterlight programs or retooling machines) are getting abolished by accustomed bread-and-butter change (fewer such orders as decades go by; allotment architecture revisions appropriate reprogramming anyway; newer, higher-capability machines now auspiciously poaching the orders; etc.).