Timeline for Why are special characters such as "carriage return" represented as "^M"?
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
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| Oct 31, 2021 at 15:29 | comment | added | The Quark | @OrangeDog But it is not in ASCII that the caret notation (or "uparrow notation") was introduced. | |
| Aug 15, 2016 at 8:14 | comment | added | keshlam | That is correct, @abbafei. I started programming on ASR33 teletypes which had the older characters. | |
| Aug 15, 2016 at 5:43 | comment | added | Abbafei | @keshlam It turns out that the uparrow was actually part of ASCII itself :-) The caret replaced the uparrow (and the underscore replaced the leftarrow) later on. Found this out here via Wikipedia. | |
| Jun 29, 2014 at 1:13 | audit | First posts | |||
| Jun 29, 2014 at 1:13 | |||||
| Jun 11, 2014 at 0:47 | comment | added | Daniel R Hicks | The DEL code is significant (and is called DEL for "delete") because if you over-punch a paper tape with DEL (all ones) you erase the character. | |
| Jun 9, 2014 at 22:32 | comment | added | R.. GitHub STOP HELPING ICE |
Ascii DEL (^?) has nothing to do with the delete key. It's actually the standard code generated by the <--- key (also, confusingly, called backspace) on VT100-like terminals.
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| Jun 7, 2014 at 12:27 | comment | added | Daniel R Hicks | @rossmcm - Actually, ASCII 0x7F is "DEL". Or course, what Windows regards as a valid key combo likely has no relation to reality. | |
| Jun 6, 2014 at 6:49 | comment | added | rossmcm |
It's also not used just with ASCII characters anymore. Windows for example allows you to detect and act on Ctrl-Del (hold Ctrl down and press the Del key). The Del key (or Delete)has no ASCII value, yet we sometimes see it written as ^Del.
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| Jun 6, 2014 at 6:24 | comment | added | R.. GitHub STOP HELPING ICE |
It's not used only with letters. I would not define it as the control character with "the letter's numeric value" but rather as "xor 64". In other words, ^A is 0x41 xor 0x40, or 0x01 and ^? is 0x3F xor 0x40, or 0x7F.
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| Jun 5, 2014 at 20:19 | comment | added | OrangeDog | This is explictly built into the ASCII design so that the Ctrl key just toggles bit 7. | |
| S Jun 5, 2014 at 14:52 | history | suggested | gws | CC BY-SA 3.0 |
address the subquestion about text editors
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| Jun 5, 2014 at 14:48 | review | Suggested edits | |||
| S Jun 5, 2014 at 14:52 | |||||
| Jun 5, 2014 at 12:56 | comment | added | keshlam | This convention goes back at least to the 1970's; I first saw it on the TOPS-10 operating system but it may well have existed earlier. For what it's worth, on older ASCII terminals the character now shown as a caret was actually an upward-pointing arrow, so this originated as "uparrow notation". | |
| Jun 5, 2014 at 12:08 | comment | added | smci | I always wondered what that thing was called... | |
| Jun 5, 2014 at 9:17 | vote | accept | dotancohen | ||
| Jun 5, 2014 at 9:17 | comment | added | dotancohen | Perfect, thank you. This is exactly what I was looking for. | |
| Jun 5, 2014 at 9:12 | history | answered | Art Gertner | CC BY-SA 3.0 |