Backspace does not erase in stdout

[Roy Smith]

In article <pan.2011.12.06.09.27.42.225000 at nowhere.com>,
 Nobody <nobody at nowhere.com> wrote:

> On Mon, 05 Dec 2011 16:23:55 +0000, Grant Edwards wrote:
> 
> >> Emitting "\b \b" is one very common way to do a destructive backspace.
> >> Inelegant? Perhaps, but a common inelegance.
> > 
> > That's pretty much the only way I've seen it done for the past 25
> > years.
> 
> ... before which, it was BS-DEL-BS.
> 
> DEL being 127 means that it punches through all of the holes on the paper
> tape, causing whatever was there previously to be replaced with a DEL
> character. BS-SPC-BS would only punch through one of the holes.

I don't remember having a DEL key on the ASR-33.  It did have a RUBOUT 
key (http://regmedia.co.uk/2010/06/21/teletype_hereis.jpg) which 
performed the function you describe.  I don't remember if that actually 
sent a 177 code over the wire or if it was a purely local function.

Also, the BS code only caused the printhead to back up.  If you wanted 
to back up the tape, you had to press the "B. SP." button the the punch 
(http://pichotjm.free.fr/Multi8/TTY/ASR33-3.html).

Of course, sending a BS-SPS-BS sequence on a printing terminal didn't do 
anything about erasing what had previously been printed.  To do that, 
you needed one of those fancy vee-de-oh things.  On the ASR-33, to 
prevent passwords from being readable, you either disabled echo, or sent 
something like BS-*-BS-X-BS-$-BS-%-BS-#-BS- at -BS-&-BS-H-BS-Z-BS-M in the 
hopes that nothing would be readable under all that garbage.