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Comment by rgoulter | Hacker News Reader

> \n is ^J (ctrl-J) so there's some logic there

The same 'j' as vi uses for 'hjkl'. https://vi.stackexchange.com/questions/42426/why-did-vi-use-...

also the same 'j' found in words like 'jujuism', 'jejunities', and 'bejeezus', also by a magical coincidence the same one in most Latin fonts, and even some random text strings such as 'pj$4'

But I suppose you're saying ASCII 10 was chosen as newly because it aligns with the down arrow on keyboards of the time. Maybe.

> I suppose you're saying ASCII 10 was chosen as newly because it aligns with the down arrow on keyboards of the time. Maybe.

The linked StackExchange has it as:

> What character was used for what control code was mostly a matter of bitwise arithmetics. LF is ^J because J happens to be at the corresponding location in the corresponding column of the table (+ 64 in decimal)

and did they choose that code because the J key had a down arrow printed on it?

No, the Baudot / Western Union mechanical teletype code assignments were worked out in the late 1800s and early 1900s. This was later developed into ASCII. Computer keyboards came much later. https://en.wikipedia.org/wiki/Baudot_code

Other way around. ASCII classified control characters into blocks and newline ended up a bit-flip away from J, so the ADM-3A printed ‘↓’ on the ‘J’ key.

Yes, and ADM-3A also had "↑" on the "K" key, because \013 is vertical tabulation (VT), and "→" on the "L" because \014 is form feed (FF). It all makes perfect sense.

If terminfo database is to be believed, quite a lot of other terminals reused this control sequences too, for some reason.

In the era when video terminals were new I have to guess that K and L were just plausibly related enough to justify using them for additional cursor motions, after H and J fit exactly.

No, it's ^J because `J` is 0x4A in ASCII and `\n` is 0x0A, just as `I` is 0x49 and `\t` (tab, ^I) is 0x09.

In the stone age, pressing CTRL flipped that bit, so ^J is literally "ctrl-J".

You're saying the same thing. vi uses ‘j’ because the ADM-3A printed ‘↓’ on the ‘J’ key because Control-J is newline because the code is J with a bit flipped because bit-flipping was practical on an electromechanical teletype.

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