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Re: backspace in wscons console sends ^H to processes

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: (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 Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email:             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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