Dan Cross <crossd@gmail.com> wrote:

> I wonder if anyone can shed any light on the timing and rationale for
> the introduction of “word erase” functionality to the kernel terminal
> driver. My surface skim earlier leads me to believe it came to Unix
> with 4BSD, but it was not reincorporated into 8th Edition or later,
> nor did it make it to Plan 9 (which did incorporate ^U for the "line
> kill" command).  TOPS-20 supports it via the familiar ^W, but I'm not
> sure about other PDP-10 OSes (Lars?).  Multics does not support it.
> VMS does not support it.
>
> What was the proximal inspiration?  The early terminal drivers seem to
> use the Multics command editing suite (`#` for erase/backspace, `@`
> for line kill), though at some point that changed, one presumes as
> TTYs fell out of favor and display terminals came to the fore.
>
>         - Dan C.

My memory jibes with this -- through V7 defaults were # and @, and BSD
changed to ^H / DEL and ^U.  ^W was a BSD thing, probably inspired by
TOPS-10.

There was a patch on USENET that added ^T to print the load average that
we put into the vax at Georgia Tech.  A professor who'd come to us from MIT
saw it and was surprised tht we could do it on Unix. :-)