Delete character

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Not to be confused with delete key.

In computing, the delete character (sometimes also called rubout) is the last character in the ASCII repertoire, with the code 127 (decimal).[1] Not a graphic character, it is denoted as ^? in caret notation and has a graphic representation in Unicode (as all other ASCII control characters have graphic representations).

There is no common method to input this character on modern keyboards, although in some environments (especially, Unix-like systems) the Backspace key or combination of Control and Backspace in, for example, Notepad may generate this code.

? 
A sample of the delete character is above.
It may be invisible in some environments.

History[edit]

  ·     NUL
· CR
· LF
· DEL
· SP
"Delete" along with some other ASCII control characters and space as they appear on punched tape

This code was originally used to mark deleted characters on punched tape, since any character could be changed to all ones by punching holes everywhere. If a character was punched erroneously, punching out all seven bits caused this position to be ignored (or deleted).[2][3] In hexadecimal, this is 7F to rubout 7 bits, and FF to rubout 8 bits. For teletypes like the ASR-33 & 35, lines were commonly ended by the three characters CR, LF, and rubout, with the rubout allowing time for the print mechanism to physically move to the left margin. On VT100 compatible terminals, this is the character generated by the key labeled Delete, which transmits a delete character (octal 177) to the host system.[4][5] On VT510 compatible terminals, this is the character generated by the key labeled , usually called backspace on modern machines, and does not correspond to the PC "Delete" key.[6]

Current use[edit]

Unix-like operating systems are known to use it as erase control character, i.e. to delete the previous character in the line mode. This, though, differs from its original function where this code replaced (physically) characters on a punched tape to be deleted.

DOS/Windows never used this character in any way, using the backspace (0x08, or control-H) to delete the previous character. EGA/VGA fonts, as fonts used by Win32 console, usually have the "house" symbol at 127 (0x7F) code point, see Code page 437 for details.

See also[edit]

References[edit]