In 1981 I was a grad student at CMU, which was running 4.1 or 4.2 at the
time.  I had spent the previous three years at IBM Research where someone
had built some editing stuff into the command line machinery for CMS.

I implemented some input line editing stuff both for the Perq and as a
module for the one of the UNIX shells and shared them with some of the
systems folks at CMU.  I do not know if they were adopted from my
implementations ... I am inclined to think not ... there was significant
skepticism of the value of command line editing among some of the systems
folks.

But the idea of retrieving previous command lines and editing the command
line was emerging as a thing in the early 1980s.
=====
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On Mon, Apr 8, 2024 at 11:03 AM 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.
>