65-580: Algerian Braille was a braille alphabet used to write the Arabic language in Algeria . It is apparently obsolete. In Algerian Braille, the braille letters are assigned in numeric order to the Arabic alphabet ; standard Arabic Braille on the other hand uses a completely different assignment, following international norms based on the order of the French alphabet. For example, the fifth braille letter, ⠑ ,
130-400: A braille embosser (printer) or a refreshable braille display (screen). Braille has been extended to an 8-dot code , particularly for use with braille embossers and refreshable braille displays. In 8-dot braille the additional dots are added at the bottom of the cell, giving a matrix 4 dots high by 2 dots wide. The additional dots are given the numbers 7 (for the lower-left dot) and 8 (for
195-456: A communication channel or storage in a storage medium . An early example is an invention of language , which enabled a person, through speech , to communicate what they thought, saw, heard, or felt to others. But speech limits the range of communication to the distance a voice can carry and limits the audience to those present when the speech is uttered. The invention of writing , which converted spoken language into visual symbols , extended
260-570: A slate and stylus , a braille writer , an electronic braille notetaker or with the use of a computer connected to a braille embosser . Braille is named after its creator, Louis Braille , a Frenchman who lost his sight as a result of a childhood accident. In 1824, at the age of fifteen, he developed the braille code based on the French alphabet as an improvement on night writing . He published his system, which subsequently included musical notation , in 1829. The second revision, published in 1837,
325-526: A word space . Dot configurations can be used to represent a letter, digit, punctuation mark, or even a word. Early braille education is crucial to literacy, education and employment among the blind. Despite the evolution of new technologies, including screen reader software that reads information aloud, braille provides blind people with access to spelling, punctuation and other aspects of written language less accessible through audio alone. While some have suggested that audio-based technologies will decrease
390-432: A corresponding sequence of amino acids that form a protein molecule; a type of codon called a stop codon signals the end of the sequence. In mathematics , a Gödel code was the basis for the proof of Gödel 's incompleteness theorem . Here, the idea was to map mathematical notation to a natural number (using a Gödel numbering ). There are codes using colors, like traffic lights , the color code employed to mark
455-598: A front for the American Black Chamber run by Herbert Yardley between the First and Second World Wars. The purpose of most of these codes was to save on cable costs. The use of data coding for data compression predates the computer era; an early example is the telegraph Morse code where more-frequently used characters have shorter representations. Techniques such as Huffman coding are now used by computer-based algorithms to compress large data files into
520-459: A greater number of symbols. (See Gardner–Salinas braille codes .) Luxembourgish Braille has adopted eight-dot cells for general use; for example, accented letters take the unaccented versions plus dot 8. Braille was the first writing system with binary encoding . The system as devised by Braille consists of two parts: Within an individual cell, the dot positions are arranged in two columns of three positions. A raised dot can appear in any of
585-405: A maximum of 42 cells per line (its margins are adjustable), and typical paper allows 25 lines per page. A large interlining Stainsby has 36 cells per line and 18 lines per page. An A4-sized Marburg braille frame, which allows interpoint braille (dots on both sides of the page, offset so they do not interfere with each other), has 30 cells per line and 27 lines per page. A Braille writing machine
650-412: A more compact form for storage or transmission. Character encodings are representations of textual data. A given character encoding may be associated with a specific character set (the collection of characters which it can represent), though some character sets have multiple character encodings and vice versa. Character encodings may be broadly grouped according to the number of bytes required to represent
715-410: A sequence of target symbols. In this section, we consider codes that encode each source (clear text) character by a code word from some dictionary, and concatenation of such code words give us an encoded string. Variable-length codes are especially useful when clear text characters have different probabilities; see also entropy encoding . A prefix code is a code with the "prefix property": there
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#1732801253410780-659: A single character: there are single-byte encodings, multibyte (also called wide) encodings, and variable-width (also called variable-length) encodings. The earliest character encodings were single-byte, the best-known example of which is ASCII . ASCII remains in use today, for example in HTTP headers . However, single-byte encodings cannot model character sets with more than 256 characters. Scripts that require large character sets such as Chinese, Japanese and Korean must be represented with multibyte encodings. Early multibyte encodings were fixed-length, meaning that although each character
845-411: A skunk!"), or AYYLU ("Not clearly coded, repeat more clearly."). Code words were chosen for various reasons: length , pronounceability , etc. Meanings were chosen to fit perceived needs: commercial negotiations, military terms for military codes, diplomatic terms for diplomatic codes, any and all of the preceding for espionage codes. Codebooks and codebook publishers proliferated, including one run as
910-611: A space-saving mechanism; and grade 3 – various non-standardized personal stenographies that are less commonly used. In addition to braille text (letters, punctuation, contractions), it is also possible to create embossed illustrations and graphs, with the lines either solid or made of series of dots, arrows, and bullets that are larger than braille dots. A full braille cell includes six raised dots arranged in two columns, each column having three dots. The dot positions are identified by numbers from one to six. There are 64 possible combinations, including no dots at all for
975-618: A system much more like shorthand. Today, there are braille codes for over 133 languages. In English, some variations in the braille codes have traditionally existed among English-speaking countries. In 1991, work to standardize the braille codes used in the English-speaking world began. Unified English Braille (UEB) has been adopted in all seven member countries of the International Council on English Braille (ICEB) as well as Nigeria. For blind readers, braille
1040-469: A text interfered with following the alignment of the letters, and consequently made texts more difficult to read than Braille's more arbitrary letter assignment. Finally, there are braille scripts that do not order the codes numerically at all, such as Japanese Braille and Korean Braille , which are based on more abstract principles of syllable composition. Texts are sometimes written in a script of eight dots per cell rather than six, enabling them to encode
1105-439: Is a total function mapping each symbol from S to a sequence of symbols over T. The extension C ′ {\displaystyle C'} of C {\displaystyle C} , is a homomorphism of S ∗ {\displaystyle S^{*}} into T ∗ {\displaystyle T^{*}} , which naturally maps each sequence of source symbols to
1170-603: Is a typewriter with six keys that allows the user to write braille on a regular hard copy page. The first Braille typewriter to gain general acceptance was invented by Frank Haven Hall (Superintendent of the Illinois School for the Blind ), and was presented to the public in 1892. The Stainsby Brailler, developed by Henry Stainsby in 1903, is a mechanical writer with a sliding carriage that moves over an aluminium plate as it embosses Braille characters. An improved version
1235-472: Is an independent writing system, rather than a code of printed orthography. Braille is derived from the Latin alphabet, albeit indirectly. In Braille's original system, the dot patterns were assigned to letters according to their position within the alphabetic order of the French alphabet of the time, with accented letters and w sorted at the end. Unlike print, which consists of mostly arbitrary symbols,
1300-558: Is difficult or impossible. For example, semaphore , where the configuration of flags held by a signaler or the arms of a semaphore tower encodes parts of the message, typically individual letters, and numbers. Another person standing a great distance away can interpret the flags and reproduce the words sent. In information theory and computer science , a code is usually considered as an algorithm that uniquely represents symbols from some source alphabet , by encoded strings, which may be in some other target alphabet. An extension of
1365-530: Is dot 5, which combines with the first letter of words. With the letter ⠍ m , the resulting word is ⠐ ⠍ mother . There are also ligatures ("contracted" letters), which are single letters in braille but correspond to more than one letter in print. The letter ⠯ and , for example, is used to write words with the sequence a-n-d in them, such as ⠛ ⠗ ⠯ grand . Most braille embossers support between 34 and 40 cells per line, and 25 lines per page. A manually operated Perkins braille typewriter supports
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#17328012534101430-399: Is extended by adding the decade dots, whereas in the fifth decade it is extended by shifting it downward. Originally there had been nine decades. The fifth through ninth used dashes as well as dots, but they proved to be impractical to distinguish by touch under normal conditions and were soon abandoned. From the beginning, these additional decades could be substituted with what we now know as
1495-529: Is no valid code word in the system that is a prefix (start) of any other valid code word in the set. Huffman coding is the most known algorithm for deriving prefix codes. Prefix codes are widely referred to as "Huffman codes" even when the code was not produced by a Huffman algorithm. Other examples of prefix codes are country calling codes , the country and publisher parts of ISBNs , and the Secondary Synchronization Codes used in
1560-562: Is read as capital 'A', and ⠼ ⠁ as the digit '1'. Basic punctuation marks in English Braille include: ⠦ is both the question mark and the opening quotation mark. Its reading depends on whether it occurs before a word or after. ⠶ is used for both opening and closing parentheses. Its placement relative to spaces and other characters determines its interpretation. Punctuation varies from language to language. For example, French Braille uses ⠢ for its question mark and swaps
1625-621: Is used in Algerian Braille for ج j , the fifth letter of the Algerian/Arabic alphabet. In most braille alphabets today, ⠑ is used for e , the fifth letter of the French/Latin alphabet, or for a letter that sounds like e , no matter where it occurs in those alphabets. Algerian-type remapping was common in early braille adaptations, but was largely abandoned in favor of mutually understandable standards beginning with
1690-511: The UMTS WCDMA 3G Wireless Standard. Kraft's inequality characterizes the sets of codeword lengths that are possible in a prefix code. Virtually any uniquely decodable one-to-many code, not necessarily a prefix one, must satisfy Kraft's inequality. Codes may also be used to represent data in a way more resistant to errors in transmission or storage. This so-called error-correcting code works by including carefully crafted redundancy with
1755-621: The Unicode character set; UTF-8 is the most common encoding of text media on the Internet. Biological organisms contain genetic material that is used to control their function and development. This is DNA , which contains units named genes from which messenger RNA is derived. This in turn produces proteins through a genetic code in which a series of triplets ( codons ) of four possible nucleotides can be translated into one of twenty possible amino acids . A sequence of codons results in
1820-453: The slate and stylus is a portable writing tool, much like the pen and paper for the sighted. Errors can be erased using a braille eraser or can be overwritten with all six dots ( ⠿ ). Interpoint refers to braille printing that is offset, so that the paper can be embossed on both sides, with the dots on one side appearing between the divots that form the dots on the other. Using a computer or other electronic device, Braille may be produced with
1885-422: The French order of the decade was u v x y z ç é à è ù ( ⠥ ⠧ ⠭ ⠽ ⠵ ⠯ ⠿ ⠷ ⠮ ⠾ ). The next ten letters, ending in w , are the same again, except that for this series position 6 (purple dot in the bottom right corner of the cell in the table above) is used without a dot at position 3. In French braille these are the letters â ê î ô û ë ï ü œ w ( ⠡ ⠣ ⠩ ⠹ ⠱ ⠫ ⠻ ⠳ ⠪ ⠺ ). W had been tacked onto
1950-470: The addition of a dot at position 3 (red dots in the bottom left corners of the cells in the table below): ⠅ ⠇ ⠍ ⠝ ⠕ ⠏ ⠟ ⠗ ⠎ ⠞ : The next ten letters (the next " decade ") are the same again, but with dots also at both position 3 and position 6 (green dots in the bottom rows of the cells in the table above). Here w was left out as it was not part of the official French alphabet in Braille's time;
2015-401: The alphabet – thus the code was unable to render the orthography of the words. Second, the 12-dot symbols could not easily fit beneath the pad of the reading finger. This required the reading finger to move in order to perceive the whole symbol, which slowed the reading process. (This was because Barbier's system was based only on the number of dots in each of two 6-dot columns, not
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2080-460: The braille alphabet follows a logical sequence. The first ten letters of the alphabet, a – j , use the upper four dot positions: ⠁ ⠃ ⠉ ⠙ ⠑ ⠋ ⠛ ⠓ ⠊ ⠚ (black dots in the table below). These stand for the ten digits 1 – 9 and 0 in an alphabetic numeral system similar to Greek numerals (as well as derivations of it, including Hebrew numerals , Cyrillic numerals , Abjad numerals , also Hebrew gematria and Greek isopsephy ). Though
2145-553: The braille letters according to the sort order of the print alphabet being transcribed; and reassigning the letters to improve the efficiency of writing in braille. Under international consensus, most braille alphabets follow the French sorting order for the 26 letters of the basic Latin alphabet , and there have been attempts at unifying the letters beyond these 26 (see international braille ), though differences remain, for example, in German Braille . This unification avoids
2210-552: The chaos of each nation reordering the braille code to match the sorting order of its print alphabet, as happened in Algerian Braille , where braille codes were numerically reassigned to match the order of the Arabic alphabet and bear little relation to the values used in other countries (compare modern Arabic Braille , which uses the French sorting order), and as happened in an early American version of English Braille, where
2275-457: The code for representing sequences of symbols over the source alphabet is obtained by concatenating the encoded strings. Before giving a mathematically precise definition, this is a brief example. The mapping is a code, whose source alphabet is the set { a , b , c } {\displaystyle \{a,b,c\}} and whose target alphabet is the set { 0 , 1 } {\displaystyle \{0,1\}} . Using
2340-404: The confidentiality of communications, although ciphers are now used instead. Secret codes intended to obscure the real messages, ranging from serious (mainly espionage in military, diplomacy, business, etc.) to trivial (romance, games) can be any kind of imaginative encoding: flowers , game cards, clothes, fans, hats, melodies, birds, etc., in which the sole requirement is the pre-agreement on
2405-399: The dots are assigned in no obvious order, the cells with the fewest dots are assigned to the first three letters (and lowest digits), abc = 123 ( ⠁ ⠃ ⠉ ), and to the three vowels in this part of the alphabet, aei ( ⠁ ⠑ ⠊ ), whereas the even digits 4 , 6 , 8 , 0 ( ⠙ ⠋ ⠓ ⠚ ) are right angles. The next ten letters, k – t , are identical to a – j respectively, apart from
2470-469: The end of 39 letters of the French alphabet to accommodate English. The a – j series shifted down by one dot space ( ⠂ ⠆ ⠒ ⠲ ⠢ ⠖ ⠶ ⠦ ⠔ ⠴ ) is used for punctuation. Letters a ⠁ and c ⠉ , which only use dots in the top row, were shifted two places for the apostrophe and hyphen: ⠄ ⠤ . (These are also the decade diacritics, on the left in the table below, of the second and third decade.) In addition, there are ten patterns that are based on
2535-484: The extension of the code, the encoded string 0011001 can be grouped into codewords as 0 011 0 01, and these in turn can be decoded to the sequence of source symbols acab . Using terms from formal language theory , the precise mathematical definition of this concept is as follows: let S and T be two finite sets, called the source and target alphabets , respectively. A code C : S → T ∗ {\displaystyle C:\,S\to T^{*}}
2600-490: The first braille translator written in a portable programming language. DOTSYS III was developed for the Atlanta Public Schools as a public domain program. Code In communications and information processing , code is a system of rules to convert information —such as a letter , word , sound, image, or gesture —into another form, sometimes shortened or secret , for communication through
2665-467: The first two letters ( ⠁ ⠃ ) with their dots shifted to the right; these were assigned to non-French letters ( ì ä ò ⠌ ⠜ ⠬ ), or serve non-letter functions: ⠈ (superscript; in English the accent mark), ⠘ (currency prefix), ⠨ (capital, in English the decimal point ), ⠼ ( number sign ), ⠸ (emphasis mark), ⠐ (symbol prefix). The first four decades are similar in that the numeric sequence
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2730-425: The infantry on the battlefield, etc. Communication systems for sensory impairments, such as sign language for deaf people and braille for blind people, are based on movement or tactile codes. Musical scores are the most common way to encode music . Specific games have their own code systems to record the matches, e.g. chess notation . In the history of cryptography , codes were once common for ensuring
2795-507: The left column and at the top of the right column: that is, the letter ⠍ m . The lines of horizontal braille text are separated by a space, much like visible printed text, so that the dots of one line can be differentiated from the braille text above and below. Different assignments of braille codes (or code pages ) are used to map the character sets of different printed scripts to the six-bit cells. Braille assignments have also been created for mathematical and musical notation. However, because
2860-443: The letters w , x , y , z were reassigned to match English alphabetical order. A convention sometimes seen for letters beyond the basic 26 is to exploit the physical symmetry of braille patterns iconically, for example, by assigning a reversed n to ñ or an inverted s to sh . (See Hungarian Braille and Bharati Braille , which do this to some extent.) A third principle was to assign braille codes according to frequency, with
2925-465: The lower-right dot). Eight-dot braille has the advantages that the casing of each letter is coded in the cell and that every printable ASCII character can be encoded in a single cell. All 256 (2 ) possible combinations of 8 dots are encoded by the Unicode standard. Braille with six dots is frequently stored as Braille ASCII . The first 25 braille letters, up through the first half of the 3rd decade, transcribe a–z (skipping w ). In English Braille,
2990-472: The meaning by both the sender and the receiver. Other examples of encoding include: Other examples of decoding include: Acronyms and abbreviations can be considered codes, and in a sense, all languages and writing systems are codes for human thought. International Air Transport Association airport codes are three-letter codes used to designate airports and used for bag tags . Station codes are similarly used on railways but are usually national, so
3055-408: The need for braille, technological advancements such as braille displays have continued to make braille more accessible and available. Braille users highlight that braille remains as essential as print is to the sighted. ⠏ ⠗ ⠑ ⠍ ⠊ ⠑ ⠗ Braille was based on a tactile code , now known as night writing , developed by Charles Barbier . (The name "night writing" was later given to it when it
3120-415: The nominal value of the electrical resistors or that of the trashcans devoted to specific types of garbage (paper, glass, organic, etc.). In marketing , coupon codes can be used for a financial discount or rebate when purchasing a product from a (usual internet) retailer. In military environments, specific sounds with the cornet are used for different uses: to mark some moments of the day, to command
3185-481: The number sign ( ⠼ ) applied to the earlier decades, though that only caught on for the digits (the old 5th decade being replaced by ⠼ applied to the 1st decade). The dash occupying the top row of the original sixth decade was simply omitted, producing the modern fifth decade. (See 1829 braille .) Historically, there have been three principles in assigning the values of a linear script (print) to Braille: Using Louis Braille's original French letter values; reassigning
3250-399: The on-screen braille input keyboard, to type braille symbols on to their device by placing their fingers on to the screen according to the dot configuration of the symbols they wish to form. These symbols are automatically translated into print on the screen. The different tools that exist for writing braille allow the braille user to select the method that is best for a given task. For example,
3315-445: The pattern of the dots.) Third, the code did not include symbols for numerals or punctuation. Braille's solution was to use 6-dot cells and to assign a specific pattern to each letter of the alphabet. Braille also developed symbols for representing numerals and punctuation. At first, braille was a one-to-one transliteration of the French alphabet, but soon various abbreviations (contractions) and even logograms were developed, creating
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#17328012534103380-537: The quotation marks and parentheses (to ⠶ and ⠦ ⠴ ); it uses ( ⠲ ) for both the period and the decimal point, and the English decimal point ( ⠨ ) to mark capitalization. Braille contractions are words and affixes that are shortened so that they take up fewer cells. In English Braille, for example, the word afternoon is written with just three letters, ⠁ ⠋ ⠝ ⟨afn⟩ , much like stenoscript . There are also several abbreviation marks that create what are effectively logograms . The most common of these
3445-412: The range of communication across space and time . The process of encoding converts information from a source into symbols for communication or storage. Decoding is the reverse process, converting code symbols back into a form that the recipient understands, such as English or/and Spanish. One reason for coding is to enable communication in places where ordinary plain language , spoken or written,
3510-417: The rest of that decade is rounded out with the ligatures and, for, of, the, and with . Omitting dot 3 from these forms the 4th decade, the ligatures ch, gh, sh, th, wh, ed, er, ou, ow and the letter w . (See English Braille .) Various formatting marks affect the values of the letters that follow them. They have no direct equivalent in print. The most important in English Braille are: That is, ⠠ ⠁
3575-530: The same information to be sent with fewer characters , more quickly, and less expensively. Codes can be used for brevity. When telegraph messages were the state of the art in rapid long-distance communication, elaborate systems of commercial codes that encoded complete phrases into single mouths (commonly five-minute groups) were developed, so that telegraphers became conversant with such "words" as BYOXO ("Are you trying to weasel out of our deal?"), LIOUY ("Why do you not answer my question?"), BMULD ("You're
3640-554: The simplest patterns (quickest ones to write with a stylus) assigned to the most frequent letters of the alphabet. Such frequency-based alphabets were used in Germany and the United States in the 19th century (see American Braille ), but with the invention of the braille typewriter their advantage disappeared, and none are attested in modern use – they had the disadvantage that the resulting small number of dots in
3705-414: The six positions, producing 64 (2 ) possible patterns, including one in which there are no raised dots. For reference purposes, a pattern is commonly described by listing the positions where dots are raised, the positions being universally numbered, from top to bottom, as 1 to 3 on the left and 4 to 6 on the right. For example, dot pattern 1-3-4 describes a cell with three dots raised, at the top and bottom in
3770-415: The six-dot braille cell allows only 64 (2 ) patterns, including space, the characters of a braille script commonly have multiple values, depending on their context. That is, character mapping between print and braille is not one-to-one. For example, the character ⠙ corresponds in print to both the letter d and the digit 4 . In addition to simple encoding, many braille alphabets use contractions to reduce
3835-404: The size of braille texts and to increase reading speed. (See Contracted braille .) Braille may be produced by hand using a slate and stylus in which each dot is created from the back of the page, writing in mirror image, or it may be produced on a braille typewriter or Perkins Brailler , or an electronic Brailler or braille notetaker. Braille users with access to smartphones may also activate
3900-422: The stored (or transmitted) data. Examples include Hamming codes , Reed–Solomon , Reed–Muller , Walsh–Hadamard , Bose–Chaudhuri–Hochquenghem , Turbo , Golay , algebraic geometry codes , low-density parity-check codes , and space–time codes . Error detecting codes can be optimised to detect burst errors , or random errors . A cable code replaces words (e.g. ship or invoice ) with shorter words, allowing
3965-443: The unification of French, English, German, and Arabic Braille on the original order in 1878. Braille alphabet Braille ( / ˈ b r eɪ l / BRAYL , French: [bʁɑj] ) is a tactile writing system used by people who are visually impaired . It can be read either on embossed paper or by using refreshable braille displays that connect to computers and smartphone devices. Braille can be written using
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#17328012534104030-454: Was considered as a means for soldiers to communicate silently at night and without a light source, but Barbier's writings do not use this term and suggest that it was originally designed as a simpler form of writing and for the visually impaired.) In Barbier's system, sets of 12 embossed dots were used to encode 36 different sounds. Braille identified three major defects of the code: first, the symbols represented phonetic sounds and not letters of
4095-767: Was introduced around 1933. In 1951 David Abraham, a woodworking teacher at the Perkins School for the Blind , produced a more advanced Braille typewriter, the Perkins Brailler . Braille printers or embossers were produced in the 1950s. In 1960 Robert Mann, a teacher in MIT, wrote DOTSYS , a software that allowed automatic braille translation , and another group created an embossing device called "M.I.T. Braillemboss". The Mitre Corporation team of Robert Gildea, Jonathan Millen, Reid Gerhart and Joseph Sullivan (now president of Duxbury Systems) developed DOTSYS III,
4160-500: Was represented by more than one byte, all characters used the same number of bytes ("word length"), making them suitable for decoding with a lookup table. The final group, variable-width encodings, is a subset of multibyte encodings. These use more complex encoding and decoding logic to efficiently represent large character sets while keeping the representations of more commonly used characters shorter or maintaining backward compatibility properties. This group includes UTF-8 , an encoding of
4225-749: Was the first binary form of writing developed in the modern era. Braille characters are formed using a combination of six raised dots arranged in a 3 × 2 matrix, called the braille cell. The number and arrangement of these dots distinguishes one character from another. Since the various braille alphabets originated as transcription codes for printed writing, the mappings (sets of character designations) vary from language to language, and even within one; in English braille there are three levels: uncontracted – a letter-by-letter transcription used for basic literacy; contracted – an addition of abbreviations and contractions used as
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