Re: Which key shortcuts are safe to bind and some Q:s about history and OS diffs Re: Ctrl+4 means SIGQUIT+coredump, where is this documented, what more shortcuts are there?

On 2018-11-01, Tinker <t1nkr@protonmail.ch> wrote:

>> > No idea how ^4 is mapped to ^\, but for some reason it is,
>>
>> See "Table 3-5 Keys Used to Generate 7-Bit Control Characters" in
>> the VT220 Programmer Reference Manual:
>> https://vt100.net/docs/vt220-rm/table3-5.html
>
> Historial reasons, a ha.

And I'll venture a guess why DEC added those combinations: In order
to type ^[ ^\ ^] to produce the ESC, FS, GS characters, you need
keys for [ \ ]. If you look at non-English keyboard layouts, you'll
see that the corresponding keys have been re-purposed for other
characters. In the old days of national ASCII variants, even the
characters [ \ ] didn't exist in many national encodings. Later,
when extended 8-bit character sets were introduced, [ \ ] were only
made available in a secondary mapping reachable with an extra
modifier key (AltGr or such). And that's the situation right into
the present.

By contrast, combinations like ^3, ^4, ^5 were readily available
on keyboards.

https://en.wikipedia.org/wiki/ISO/IEC_646#ISO_646_national_variants

--
Christian "naddy" Weisgerber naddy@mips.inka.de