C0 controls - Revision history

Dan Tobias at 05:46, 18 March 2022

2022-03-18T05:46:08Z

Dan Tobias at 05:08, 11 June 2020

2020-06-11T05:08:10Z

Jsummers at 22:01, 4 March 2016

2016-03-04T22:01:37Z

Dan Tobias at 17:40, 6 August 2014

2014-08-06T17:40:55Z

Dan Tobias at 02:11, 25 November 2013

2013-11-25T02:11:49Z

Dan Tobias at 13:36, 26 October 2013

2013-10-26T13:36:00Z

Dan Tobias at 12:59, 14 October 2013

2013-10-14T12:59:04Z

Dan Tobias at 13:01, 17 September 2013

2013-09-17T13:01:44Z

Dan Tobias at 12:59, 17 September 2013

2013-09-17T12:59:27Z

Dan Tobias at 12:46, 17 September 2013

2013-09-17T12:46:42Z

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 |formattype=electronic
 |subcat=Character encoding
 }}
 The '''C0 controls''' are the control characters (code positions 0-31 decimal) which are part of the [[ASCII]] standard (as adopted in 1967; the earlier 1963 version had somewhat different control character assignments). They are also part of a number of other character sets derived from ASCII, and are in the [[Unicode]] set at the same code positions they have in ASCII. The official definition gives particular meanings for each of the characters, though they have also been used in a number of other ways, and some of them are rarely used these days. Some character sets (including Unicode) have a second set of controls called the [[C1 controls]] in the equivalent positions with the 8th bit set (128-159 decimal), but those are rarely used in their control meanings (the Windows character sets have printable characters there).

@@ Line 79: / Line 79: @@
 |1E||30||^^||RS||Record Separator||The third of four separator characters, subordinate to FS and GS, but higher-level than US. On Commodore computers, it set the text color to green. (Was S<sub>6</sub>, Separator 6, in 1963 version of ASCII.)
 |-
-|1F||31||^_||US||Unit Separator||The lowest-level of the separator characters, used to divide strings of ASCII characters which are the base elements of a data structure. A sequence of such US-delimited strings can in turn be used as a higher-level data element separated by other such elements by the RS character, and this structure in turn can be delimited from other such elements by GS, and finally if a fourth level is needed the FS character separates those elements. On Commodore computers, it set the text color to blue. (Was S<sub>7</sub>, Separator 7, in 1963 version of ASCII.)
+|1F||31||^_||US||Unit Separator||The lowest-level of the separator characters, used to divide strings of ASCII characters which are the base elements of a data structure. A sequence of such US-delimited strings can in turn be used as a higher-level data element separated from other such elements by the RS character, and this structure in turn can be delimited from other such elements by GS, and finally if a fourth level is needed the FS character separates those elements. On Commodore computers, it set the text color to blue. (Was S<sub>7</sub>, Separator 7, in 1963 version of ASCII.)
 |}

@@ Line 1: / Line 1: @@
 {{FormatInfo
 |formattype=electronic
-|subcat=Character Encodings
+|subcat=Character encoding
 }}
 The '''C0 controls''' are the control characters (code positions 0-31 decimal) which are part of the [[ASCII]] standard (as adopted in 1967; the earlier 1963 version had somewhat different control character assignments). They are also part of a number of other character sets derived from ASCII, and are in the [[Unicode]] set at the same code positions they have in ASCII. The official definition gives particular meanings for each of the characters, though they have also been used in a number of other ways, and some of them are rarely used these days. Some character sets (including Unicode) have a second set of controls called the [[C1 controls]] in the equivalent positions with the 8th bit set (128-159 decimal), but those are rarely used in their control meanings (the Windows character sets have printable characters there).

@@ Line 20: / Line 20: @@
 |00||0||^@, \0||NUL||Null character||Marks unused space or padding (e.g., to intentionally slow down terminals or to leave space for added data in memory or storage media). Used in C-based programming languages to mark end of string.
 |-
-|01||1||^A||SOH||Start of Heading||Marks the beginning of a header in a message or data structure. (The SOL-20 computer mapped this onto the left arrow key.) In FidoNet messages, when it occurred at the beginning of a line, it marked the line as a control header line. (Was SOM, Start of Message, in 1963 version of ASCII.)
+|01||1||^A||SOH||Start of Heading||Marks the beginning of a header in a message or data structure. The SOL-20 computer mapped this onto the left arrow key. In FidoNet messages, when it occurred at the beginning of a line, it marked the line as a control header line. (Was SOM, Start of Message, in 1963 version of ASCII.)
 |-
 |02||2||^B||STX||Start of Text||Marks the beginning of the body text of a message, and/or the end of the header. (Was EOA, End of Address, in 1963 version of ASCII.)
@@ Line 56: / Line 56: @@
 |12||18||^R||DC2||Device Control 2||Another device-control code; not used as much as DC1 and DC3. On Commodore computers, Reverse Video On.
 |-
-|13||19||^S||DC3||Device Control 3||The third of the device-control codes; this one (CTRL-S, also known as XOFF) is often used to pause processes, devices, or output streams, with CTRL-Q (XON) resuming them (though in some cases, any keypress causes output to resume). (The SOL-20 computer mapped this onto the right arrow key. Commdore computers used it for the Home key.)
+|13||19||^S||DC3||Device Control 3||The third of the device-control codes; this one (CTRL-S, also known as XOFF) is often used to pause processes, devices, or output streams, with CTRL-Q (XON) resuming them (though in some cases, any keypress causes output to resume). The SOL-20 computer mapped this onto the right arrow key. Commodore computers used it for the Home key.
 |-
 |14||20||^T||DC4||Device Control 4||The fourth device-control code; not used as much as DC1 or DC3. In DEC TOPS-20 mainframes, usually resulted in output of system status to terminal. Commodore computers used it for the Delete key. (Was called both DC<sub>4</sub> and STOP in 1963 version of ASCII.)
@@ Line 64: / Line 64: @@
 |16||22||^V||SYN||Synchronous Idle||Signals that a correction may now be received in synchronous transmission protocols. In most Windows programs, Ctrl-V pastes text from the cut/copy buffer. (Was spelled SYNC in 1963 version of ASCII.)
 |-
-|17||23||^W||ETB||End of Transmission Block||Marks the end of a block of data divided into blocks for transmission. (The SOL-20 computer mapped this onto the up arrow key.) (Was LEM, Logical End of Media, in 1963 version of ASCII.)
+|17||23||^W||ETB||End of Transmission Block||Marks the end of a block of data divided into blocks for transmission. The SOL-20 computer mapped this onto the up arrow key. (Was LEM, Logical End of Media, in 1963 version of ASCII.)
 |-
-|18||24||^X||CAN||Cancel||Cancels an operation and signals that previously-sent data can be disregarded. (The SOL-20 computer mapped this onto the down arrow key. In most Windows programs, Ctrl-X cuts text into a buffer for later pasting.) (Was S<sub>0</sub>, Separator 0, in 1963 version of ASCII.)
+|18||24||^X||CAN||Cancel||Cancels an operation and signals that previously-sent data can be disregarded. The SOL-20 computer mapped this onto the down arrow key. In most Windows programs, Ctrl-X cuts text into a buffer for later pasting. (Was S<sub>0</sub>, Separator 0, in 1963 version of ASCII.)
 |-
 |19||25||^Y||EM||End of Medium||Marks the end of a physical medium such as a data-storage tape. In most Windows programs, Ctrl-Y redoes a command after Ctrl-Z undid it. (Was S<sub>1</sub>, Separator 1, in 1963 version of ASCII.)

@@ Line 36: / Line 36: @@
 |08||8||^H, \b||BS||Backspace||Moves back one space. Usually deletes last character (e.g., from input string), but on some old terminals it just moved backward without deleting and allowed "overstrike" effects overlaying multiple characters. On Apple II, represented left arrow. On Commodore computers, disables character set switching. (Was FE<sub>0</sub>, Format Effector, in 1963 version of ASCII.)
 |-
-|09||9||^I, \t||HT||Horizontal Tab||The typewriter "tab key", usually moving to the next tab stop as defined in the particular software being used. On Commodore computers, enables character set switching. (Was HT / SK in 1963 version of ASCII, representing [[Punched card|punchcard]] skip as well as tab.)
+|09||9||^I, \t||HT||Horizontal Tab||The typewriter "tab key", usually moving to the next tab stop as defined in the particular software being used. (But some think [http://www.emacswiki.org/emacs/TabsAreEvil Tabs Are Evil]!) On Commodore computers, enables character set switching. (Was HT / SK in 1963 version of ASCII, representing [[Punched card|punchcard]] skip as well as tab.)
 |-
 |0A||10||^J, \n||LF||Line Feed||Move down one line. In Unix-style operating systems, it also moves to the beginning of the next line so that it can be used as a line break (newline) character, while in some other systems and terminals it just moves down without moving to the left, requiring the "CR LF" sequence to break a line. On Apple II, represented down arrow (on later machines that had a down arrow key).

@@ Line 34: / Line 34: @@
 |07||7||^G, \a||BEL||Bell||On some systems, this causes a bell, buzzer, or beep to sound, or flashes inverse video to alert a system operator. The Apple II had "BELL" on the "G" key to remind users that Ctrl-G caused this sound effect. Try putting Ctrl-G in an ECHO command from the command line window in Windows even now; it still works. Every time this character is sent to a terminal, an angel gets its wings! (Was spelled BELL in 1963 version of ASCII.)
 |-
-|08||8||^H, \b||BS||Backspace||Moves back one space. Usually deletes last character (e.g., from input string), but on some old terminals it just moved backward without deleting and allowed "overstrike" effects overlaying multiple characters. On Commodore computers, disables character set switching. (Was FE<sub>0</sub>, Format Effector, in 1963 version of ASCII.)
+|08||8||^H, \b||BS||Backspace||Moves back one space. Usually deletes last character (e.g., from input string), but on some old terminals it just moved backward without deleting and allowed "overstrike" effects overlaying multiple characters. On Apple II, represented left arrow. On Commodore computers, disables character set switching. (Was FE<sub>0</sub>, Format Effector, in 1963 version of ASCII.)
 |-
 |09||9||^I, \t||HT||Horizontal Tab||The typewriter "tab key", usually moving to the next tab stop as defined in the particular software being used. On Commodore computers, enables character set switching. (Was HT / SK in 1963 version of ASCII, representing [[Punched card|punchcard]] skip as well as tab.)
 |-
-|0A||10||^J, \n||LF||Line Feed||Move down one line. In Unix-style operating systems, it also moves to the beginning of the next line so that it can be used as a line break (newline) character, while in some other systems and terminals it just moves down without moving to the left, requiring the "CR LF" sequence to break a line.
+|0A||10||^J, \n||LF||Line Feed||Move down one line. In Unix-style operating systems, it also moves to the beginning of the next line so that it can be used as a line break (newline) character, while in some other systems and terminals it just moves down without moving to the left, requiring the "CR LF" sequence to break a line. On Apple II, represented down arrow (on later machines that had a down arrow key).
 |-
-|0B||11||^K, \v||VT||Vertical Tab||Moves to vertical tab stops; not used nearly as often as the more-common horizontal tab. (Was written V<sub>TAB</sub> in 1963 version of ASCII.)
+|0B||11||^K, \v||VT||Vertical Tab||Moves to vertical tab stops; not used nearly as often as the more-common horizontal tab. (Was written V<sub>TAB</sub> in 1963 version of ASCII.) On Apple II, represented up arrow (on later machines that had an up arrow key).
 |-
 |0C||12||^L, \f||FF||Form Feed||Causes page to eject in printers, and may clear the screen in some terminal emulators. Sometimes used as a logical division of sections of a document.
@@ Line 60: / Line 60: @@
 |14||20||^T||DC4||Device Control 4||The fourth device-control code; not used as much as DC1 or DC3. In DEC TOPS-20 mainframes, usually resulted in output of system status to terminal. Commodore computers used it for the Delete key. (Was called both DC<sub>4</sub> and STOP in 1963 version of ASCII.)
 |-
-|15||21||^U||NAK||Negative Acknowledge||In transmission protocols, indicates a failure requiring a re-send, or a negative response to a query of whether the process is ready to proceed. (Was ERR, Error, in 1963 version of ASCII.)
+|15||21||^U||NAK||Negative Acknowledge||In transmission protocols, indicates a failure requiring a re-send, or a negative response to a query of whether the process is ready to proceed. On Apple II, represented right arrow. (Was ERR, Error, in 1963 version of ASCII.)
 |-
 |16||22||^V||SYN||Synchronous Idle||Signals that a correction may now be received in synchronous transmission protocols. In most Windows programs, Ctrl-V pastes text from the cut/copy buffer. (Was spelled SYNC in 1963 version of ASCII.)

@@ Line 50: / Line 50: @@
 |10||16||^P||DLE||Data Link Escape||Signals the start of a sequence of raw data as opposed to normal printable or control characters.
 |-
-|11||17||^Q||DC1||Device Control 1||One of four device-control codes intended to be system-specific. This one (CTRL-Q, also known as XON) is often used to resume operations of a process, device, or output stream that has been paused with CTRL-S (XOFF). On Commdore computers, used for Cursor Down.
+|11||17||^Q||DC1||Device Control 1||One of four device-control codes intended to be system-specific. This one (CTRL-Q, also known as XON) is often used to resume operations of a process, device, or output stream that has been paused with CTRL-S (XOFF). On Commodore computers, used for Cursor Down.
 |-
 |12||18||^R||DC2||Device Control 2||Another device-control code; not used as much as DC1 and DC3. On Commodore computers, Reverse Video On.

@@ Line 80: / Line 80: @@
 |1F||31||^_||US||Unit Separator||The lowest-level of the separator characters, used to divide strings of ASCII characters which are the base elements of a data structure. A sequence of such US-delimited strings can in turn be used as a higher-level data element separated by other such elements by the RS character, and this structure in turn can be delimited from other such elements by GS, and finally if a fourth level is needed the FS character separates those elements. On Commodore computers, it set the text color to blue.
 |}
 [[Category:File format details]]