Re: backspace in wscons console sends ^H to processes

[Johnny Billquist <bqt%update.uu.se@localhost>]

First of all, as another comment - it wasn't really a DEC vs. anyone 
else with regards to BS vs DEL. DG for example also used DEL (and there 
were more).
But using DEL pretty much just comes naturally from the teletype, so if 
anyone wants to argue that BS would be more natural than DEL really 
needs to go back and look at a teletype, and see that it's clearly not 
the case there.

And I guess this reply isn't really as much a comment directly to you, 
Michael, as a general followup on the topic. But it had to come somewhere...

On 2021-07-19 23:34, Michael van Elst wrote:
> bqt%update.uu.se@localhost (Johnny Billquist) writes:
>
> > No idea why they decided on using BS.
>
> With teletypes you couldn't "backspace", a DEL would usually print
> something like a black rectangle or echo the previous character.
> You can get something similar with 'stty -echoe echoprt' (unless
> you have a too modern shell that resets the terminal driver).

IBM didn't use teletypes. Or at least not uses using ASCII. And DEL is 
an ASCII character. My point was really that IBM using BS on the PC did 
not come from their mainframe world, since they didn't even use ASCII on 
their mainframes...

And the teletype itself don't print anything when you send a DEL. DEL 
was sometimes used as a filler character, if you didn't use NUL.
Any kind of echoing when a DEL was sent to a computer was done by the 
computer echoing back the previous character or whatever.

But anyway. The big point is that teletypes actually just had a key 
labelled "rubout". That key did send a DEL character, though.
So obviously, it was pretty natural for any systems back in that day to 
adopt this by interpreting the DEL character as the user had pressed 
rubout, and when the user pressed rubout, he was most likely wanting to 
rub out the character he just typed.

When other terminals came around, the convention of using DEL to 
indicate that you wanted to rub out characters were already established 
from the teletype, and it was pretty natural to just continue doing the 
same.

> The notion of "backspacing" and then overwriting the input probably
> comes from video displays. And there I only remember the use of
> BS to erase the last character and move the cursor left while DEL
> was erasing the character under the cursor and shift the remainder
> of the line.

Yes, using BS most likely came with some manufacturers when video 
terminals started showing up. But it also meant breaking with an already 
well established convention.

Very unfortunate, if you ask me, and it continues to be an issue to this 
day. But before IBM did that on the PC, it was a bit uncommon to see BS 
used for this. But since then, it has become very predominant.

I still change my systems back to using DEL everywhere, because I prefer 
this. But each one to his own. I don't feel a need to mess others up 
just because I disagree with them. Others obviously feel different about 
the topic.

> The original VT100 also chose to have a Backspace and a Delete key
> next to each other.

Yes. And DEC software used BS as a sort of complement to TAB sometimes. 
So BS was also still possible to have on VT200 and newer terminals, if 
you ran them in VT100-compatible mode.

> > But I also always configure things around so that that key sends DEL
> > everywhere I am.
>
> The majority of all systems nowadays seem to agree on using BS
> (0x08) for the Backarrow key. USB uses BS, PS/2 uses DEL, but
> which is older? :)

I'd say the teletype beats them all. :-)

> RedHat once tried to force everything to use DEL, but it probably
> didn't work out as the patches are gone. Forcing everything to use
> BS is probably as futile.

Agreed. Just let people use whatever they prefer. (Even going back to 
the Unix # and @ if they really want to.)

> I have a theory that only emacs users nowadays want it to send DEL
> so that they can use BS for "Help".

Well, anyone using some other operating systems might also want things 
differently...

> N.B. The original VT100 also had a linefeed key. Now try to imagine
> how the world would look like if Richard Stallman had been a Wordstar
> lover where LF (Ctrl-J) was the help function.

Emacs tried, when possible, to use keys which did have some natural 
association with the function. Thus ^H for HELP actually is sortof 
proper. ^J is not.

  Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol