The Baudot code, named after its inventor Émile Baudot, is a character set predating EBCDIC and ASCII, and the root predecessor to International Telegraph Alphabet No 2 (ITA2), 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 communication channel such as a telegraph wire or a radio signal. For other uses, see Inventor (disambiguation). ... Jean-Maurice-Émile Baudot, (September 11, 1845 – March 28, 1903), French telegraph engineer and inventor of the Baudot code, was one of the pioneers of telecommunications. ... A character encoding or character set (sometimes referred to as code page) consists of a code that pairs a sequence of characters from a given set with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the storage of text in computers... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... Asynchronous communication can be non-electronic or electronic. ...

Baudot's original code, developed around 1874, is known as International Telegraph Alphabet No 1, and is no longer used. It was sent using a five-key keyboard where each key represented one bit of the five state signal. A mechanical wiper would scan the keyboard state and unlock the keys allowing the operator to enter the next character. Year 1874 (MDCCCLXXIV) was a common year starting on Thursday (link with display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ... This article or section does not cite any references or sources. ... This article is about the unit of information. ...

Around 1901 Baudot's code was modified by Donald Murray (1865-1945) by re-ordering the characters, adding extra characters and shift codes. Murray's re-ordering of the characters was prompted by his development of a typewriter-like keyboard. Since the layout of the bits was now disassociated from the keypress of the operator, Murray could arrange his code-set so that the most-used characters resulted in the fewest state transitions, minimizing wear on the equipment. Year 1901 (MCMI) was a common year starting on Tuesday (link will display calendar) of the Gregorian calendar (or a common year starting on Monday [1] of the 13-day-slower Julian calendar). ...

A further modification of Murray's code mostly by Western Union consisted of dropping some characters. This final modification is what is generally known as the 'Baudot code', also known as the International Telegraph Alphabet No 2 (ITA2). ITA2 is still used in TDDs and some amateur radio applications, such as radioteletype ("RTTY"). Western Union (NYSE: WU) is a financial services and communications company based in the United States. ... A telecommunications device for the deaf (TDD) is an electronic device for text communication via a telephone line, used when one or more of the parties has hearing or speech difficulties. ... Amateur radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Amateur radio, often called ham radio, is a hobby that uses various types of radio broadcasting equipment to communicate with other radio amateurs for public service, recreation and self-training. ... RadioTeleType (RTTY) is a telecommunications system consisting of two teleprinters linked by a radio link. ...

(Baudot's code was never used in any teleprinter equipment; nearly all 20th century teleprinter equipment used Western Union's code, ITA2, or variants thereof. Radio amateurs casually call ITA2 and variants "baudot" incorrectly, and even the American Radio Relay League's Amateur Radio Handbook does so, though in more recent editions the tables of codes correctly identifies it as ITA2.) The ARRL Logo. ...

Details

NOTE: This table presumes the space called "1" by Baudot and Murray is rightmost, and least significant. The actual order of transmission varied by manufacturer.

In ITA2, characters are expressed using five bits. ITA2 uses two code sub-sets, the "letter shift" (LTRS), and the "figure shift" (FIGS). The FIGS character (11011) signals that the following code is to be interpreted as being in the FIGS set, until this is reset by the LTRS (11111) character. "ENQuiry" will trigger the other machine's answerback. It means "Who are you?" Chart of International Telegraphic Alphabet #2, also known as Baudot code. ...

CR is carriage return, LF is line feed, BEL is the bell character which rang a small bell (often used to alert operators to an incoming message), SP is space, and NUL is the null character (blank tape). Originally, carriage return was the term for the key, lever, or mechanism on a typewriter that would cause the cylinder on which the paper was held (the carriage) to return to the left side of the paper after a line of text had been typed, and would often move it... In computing, line feed (LF) is a control character indicating that one line should be fed out. ... Bell character is an ASCII control character, code 7 (^G). ... A bell is a simple sound-making device. ... The null character (also null terminator) is a character with the value zero, present in the ASCII and Unicode character sets, and available in nearly all mainstream programming languages. ...

Note: the binary conversions of the codepoints are often shown in reverse order, depending on (presumably) from which side you are viewing the papertape. Note further that the "control" characters were chosen so that they were either symmetric or in useful pairs so that inserting a tape "upside down" did not result in problems for the equipment and the resulting printout could be deciphered. Thus FIGS (11011), LTRS (11111) and space (00100) are invariant, while CR (01000) and LF (00010), generally used as a pair, result in the same output when the tape is reversed. LTRS could also be used to overpunch characters to be deleted on a paper tape (much like DEL in 7-bit ASCII). In computing, a control character or non-printing character, is a code point (a number) in a character set that does not in itself represent a written symbol. ... A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ...

The sequence RYRYRY... is often used in test messages, and at the start of every transmission. Since R is 01010 and Y is 10101, the sequence exercises much of a teleprinter's mechanical components at maximum stress. Also, at one time, fine-tuning of the receiver was done using two coloured lights (one for each tone). 'RYRYRY...' produced 0101010101..., which made the lights glow with equal brightness when the tuning was correct.

US implementations of Baudot code may differ in the use of ENQ, +, and f,g,h on the FIGS layer. The above table represents the official ITA2 code.

The Russian version of Baudot code (MTK-2) used three shift modes; the Cyrillic letter mode was activated by the character (00000), unused in original ITA2. Because of the larger number of characters in the Cyrillic alphabet, the characters !, &, £, and BEL were omitted and replaced by Cyrillics. MTK-2 MTK-2 is the Russian version of Baudot code. ... The Cyrillic alphabet (or azbuka, from the old name of the first letters) is an alphabet used to write six natural Slavic languages (Belarusian, Bulgarian, Macedonian, Russian, Serbian, and Ukrainian) and many other languages of the former Soviet Union, Asia and Eastern Europe. ... An exclamation mark (also exclamation point, and (rarely) mark of admiration) is a punctuation mark. ... The roman ampersand on the left is stylised, but the italic one on the right is clearly similar to et. An ampersand (&) is a logogram representing the word and. ... The symbol £ represents the pound currency which Britain uses. ... Bell character is an ASCII control character, code 7 (^G). ...

References

• Five-unit codes
• An examination of Baudot code in respect to other character codes by Tom Jennings
• MTK-2 code table

Tom Jennings (born 1955 as Thomas Daniel Jennings in Boston, Massachusetts) is the creator of FidoNet, the first message and file networking system for BBSes. ...

See also

• Serial communication
• Asynchronous communication
• Morse code

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL. In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... Asynchronous communication can be non-electronic or electronic. ... 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting telegraphic information, using standardized sequences of short and long elements to represent the letters, numerals, punctuation and special characters of a message. ... This article does not cite any references or sources. ... “GFDL” redirects here. ...