Arrow ascii table binary and decimal period
In computing and telecommunicationa control character or non-printing character is a code point a number in a character setthat does not represent a written symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly printingprintableor graphic charactersexcept perhaps for the "space" character see ASCII printable characters. The code DEL is also a control character.
Extended ASCII sets defined by ISO added the codes through as control characters, this was primarily done so that if the high bit was stripped it would not change a printing character to a C0 control code, but there have been some assignments here, in particular NEL. This second set is called the C1 set. These 65 control codes were carried over to Unicode. Unicode added more characters that could be considered controls, but it makes a distinction between these "Formatting characters" such as the Zero-width non-joinerand the 65 Control characters.
Procedural signs in Morse code are a form of control character. A form of control characters were introduced in the Baudot code: The Murray code added the carriage return CR and line feed LFand other versions of the Baudot code included other control characters.
The bell character BELwhich rang a bell to alert operators, was also an early teletype control character. Even though many control characters are rarely used, the concept of sending device-control information intermixed with printable characters is so useful that device makers found a way to send hundreds of device instructions. Specifically, they used ASCII code 27 escapefollowed by a series of characters called a "control sequence" or " escape sequence ". Typically, code 27 was sent first in such a sequence to alert the device that the following characters were to be interpreted as a control sequence rather than as plain characters, then one or more characters would follow to specify some detailed action, after which the device would go back to interpreting characters normally.
For example, the sequence of code 27, followed by the printable characters arrow ascii table binary and decimal period, would cause a DEC VT terminal to move its cursor to the 10th cell of the 2nd line of the screen. But the number of non-standard variations in use is large, especially among printers, where technology has advanced far faster than any standards body can possibly keep up with.
Their General Category is "Cc". Formatting codes are distinct, in General Category "Cf". The Cc control characters have no Name in Unicode. There are a number of techniques to display non-printing characters, which may be illustrated with the bell character in ASCII encoding:. ASCII-based keyboards have a key labelled " Control ", "Ctrl", or rarely "Cntl" which is used much like a shift key, being pressed in arrow ascii table binary and decimal period with another letter or symbol key. In one implementation, the control key generates the code 64 places below the code for the generally uppercase letter it is pressed in combination with i.
For example, pressing "control" and arrow ascii table binary and decimal period letter "g" or "G" code in octal or 71 in base 10which is in binaryproduces the code 7 Bell, 7 in base 10, or in binary. For convenience, a lot of terminals accept Ctrl-Space as an alias for Ctrl. This approach is not able to represent the DEL character because of its value codebut Ctrl-?
When the control key is held down, letter keys produce the same control characters regardless of the state of the shift or caps lock keys.
In other words, it does not matter whether the key would have produced an upper-case or a lower-case letter. The interpretation of the control key with the space, graphics character, and digit keys ASCII codes 32 to 63 vary between systems. Some will produce the same character code as if the control key were not held arrow ascii table binary and decimal period. Other systems translate these keys into control characters when the control key is held down.
Control characters generated using letter keys are arrow ascii table binary and decimal period displayed with the upper-case form of the letter. Keyboards also typically have a few single keys which produce control character codes.
For example, the key labelled "Backspace" typically produces code 8, "Tab" code 9, "Enter" or "Return" code 13 though some keyboards might produce code 10 for "Enter". Many keyboards include keys that do not correspond to any ASCII printable or control character, for example cursor control arrows and word processing functions.
The associated keypresses are communicated to computer programs by one of four methods: Keyboards attached to stand-alone personal computers made in the s arrow ascii table binary and decimal period use one or both of the first two methods. Modern computer keyboards generate scancodes that identify the specific physical keys that are pressed; computer software then determines how to handle the keys that are pressed, including any of the four methods described above.
The control characters were designed to fall into a few groups: Printing control characters were first used to control the physical mechanism of printers, the earliest output device. An early implementation of this idea was the out-of-band ASA carriage control characters. Later, control characters were integrated into the stream of data to be printed. The carriage return character CRwhen sent to such a device, causes it to put the character at the edge of the paper at which writing begins it may, or may not, also move the printing position to the next line.
It may or may notdepending on the device and its configuration, also move the printing position to the start of the next line which would be the leftmost position for left-to-right scripts, such as the alphabets used for Western languages, and the rightmost position for right-to-left scripts such as the Hebrew and Arabic alphabets. The backspace character BS moves the printing position one character space backwards. On printers, this is most often used so the printer can overprint characters to make other, not normally available, characters.
On terminals and other electronic output devices, there are often software or hardware configuration choices which will allow a destruct backspace i. The shift in and shift out characters SO and SI selected alternate character sets, fonts, underlining or other printing modes.
Escape sequences were often used to do the same thing. With the advent of computer terminals that did not physically print on paper and so offered more flexibility regarding screen placement, erasure, and so forth, printing control codes were adapted. Form feeds, for example, usually cleared the screen, there being no new paper page to move to.
More complex escape sequences were developed to take advantage of the flexibility of the new terminals, and indeed of newer printers. The concept of a control character had always been somewhat limiting, and was extremely so when used with new, much more flexible, hardware. Control sequences sometimes implemented as escape sequences could match the new flexibility and power and became the standard method. However, there were, and remain, a large variety of standard sequences to choose from.
The separators File, Group, Record, and Unit: End of medium EM warns that the tape or other recording medium is ending. The separator control characters are not overloaded; there is no general use of them except to separate arrow ascii table binary and decimal period into structured groupings.
Their numeric values are contiguous with the space character, which can be considered a member of the group, as a word separator. The transmission control characters were intended to structure a data stream, and to manage arrow ascii table binary and decimal period or graceful failure, as needed, in the face of transmission errors. The start of heading SOH character was to mark a non-data section of a data stream—the part of a stream containing addresses and other housekeeping data. The start of text character STX marked the end of the header, and the start of the textual part of a stream.
The end of text character ETX marked the end of the data of a message. The end of transmission block character ETB was used to indicate the end of a block of data, where data was divided into such blocks for transmission purposes.
The escape character ESC was intended to "quote" the next character, if it was another control character it would print it instead of performing the control function. It is almost never used for this purpose today. Arrow ascii table binary and decimal period substitute character SUB was intended to request a translation of the next character from a printable character to another value, usually by setting bit 5 to zero. This is handy because some media such as sheets of paper produced by typewriters can transmit only printable characters.
However, on MS-DOS systems with files opened in text mode, "end of text" or "end of file" is marked by this Ctrl-Z character, instead of the Ctrl-C or Ctrl-Dwhich are common on other operating systems. The cancel character CAN signalled that the previous element should be discarded. The arrow ascii table binary and decimal period acknowledge character NAK is a definite flag for, usually, noting that reception was a problem, and, often, that the current element should be sent again.
The acknowledge character ACK is normally used as a flag to indicate no problem detected with current element. When a transmission medium is half duplex that is, it can transmit in only one direction at a timethere is usually a master station that can transmit at any time, and one or more slave stations that transmit when they have permission. The enquire character ENQ is generally used by a master station to ask a slave station to send its next message.
A slave station indicates that it has completed its transmission by sending the end of transmission character EOT. The device arrow ascii table binary and decimal period codes DC1 to DC4 were originally generic, to be implemented as necessary by each device. However, a universal need in data transmission is to request the sender to stop transmitting when a receiver can't take more data right now.
This technique, however implemented, avoids additional wires in the data cable devoted only to transmission management, which saves money. A sensible protocol for the use of such transmission flow control signals must be used, to avoid potential deadlock conditions, however. Code 7 BEL is intended to cause an audible signal in the receiving terminal.
Many of the ASCII control characters were designed for devices of the time that are not often seen today. For example, code 22, "synchronous idle" SYNwas originally sent by synchronous modems which have to send data constantly when there was no actual data to send. Modern systems typically use a start bit to announce the beginning arrow ascii table binary and decimal period a transmitted word— this is a feature of asynchronous communication. Synchronous communication links were more often seen with mainframes, where they were typically run over corporate leased lines to connect arrow ascii table binary and decimal period mainframe to another mainframe or perhaps a minicomputer.
In paper tape, it is the case when there are no holes. It is convenient to treat this as a fill character with no meaning otherwise. Since the position of a NUL character has no holes punched, it can be replaced with any other character at a later time, so it was typically used to reserve space, either for correcting errors or for inserting information that would be available at a later time or in another place.
In computing it is often used for padding in fixed length records and more commonly, to mark the end of a string. Code DELa. Its 7-bit arrow ascii table binary and decimal period is all-bits-on in binary, which essentially erased a character cell on a paper tape when overpunched.
Paper tape became obsolete in the s, so this clever aspect of ASCII rarely saw any use after that. Some systems such as the original Apples converted it to a backspace. But because its code is in the range occupied by other printable characters, and because it had no official assigned glyph, many computer equipment vendors used it as an additional printable character often an all-black "box" character useful for erasing text by overprinting with ink.
Non-erasable Programmable ROMs are typically implemented as arrays of fusible elements, each representing a bitwhich can only be switched one way, usually from one to zero. Many file systems do not allow control characters in the filenamesas they may have reserved functions. From Wikipedia, the arrow ascii table binary and decimal period encyclopedia.
For characters in text applications, see Non-printing character in word processors. This article needs additional citations for verification. Please help improve this article by adding citations to arrow ascii table binary and decimal period sources.