[TUHS] terminal - just for fun

[Mary Ann Horton]

Quoting "Jeremy C. Reed" <reed at reedmedia.net>:


> When did the sh shell provide intra-line editing?

I don't think sh ever did line editing, unless sh is a link to bash or ksh.
I first saw this in csh around 1978, ed-style.  David Korn added EMACS
editing to ksh in the early 80s, and Alan Hewitt wrote a mini-vi version
which Korn also included.  Once I had access to vi in the shell, I switched
from csh to ksh and never went back.

> How was the "HERE IS" key programmed? Was it used in Unix?

HERE IS was intended for two teletypes connected to each other via modem.
There was a short ID string hardcoded somehow into the teletype - I think
the limit was 8 or 16 characters, and if not null, typically was a short
ID of whose teletype it was (e.g. the organization name or site in the org.)
If you press HERE IS, it was as if you had typed those characters.
More interesting was that if one side of the link sent the ASCII ENQ
(enquiry, control E) character, the other side would respond with its
HERE IS string.

You were supposed to type a message offline onto paper tape (editing
with the "back space" button on the tape punch, which rewound the tape
reel one character so the most recent char was ready to be punched again)
and then type RUB OUT, which obliterated the typo.)  Then you would put
the tape in the reader, dial the number of another teletype, and press
Start on the tape reader.  Your tape would read and be transmitted to the
other side.  Sort of a primitive email system, it was widely used by news
media.  There was even a "Telex" network of these things - the Wikipedia
entry for Telex has some background and a few vintage photos.

I think if you put an ENQ at the beginning of your tape, the other side
would identify itself, so you were sure it went to the right place.
Of course, the tape kept reading, so you'd better have several NULL
characters after the ENQ.

I never tried this, my ASR33 days were spent dialing up computers, not
other teletypes.   I actually bought one of these things as a college  
sophomore so I could access the computer center from my dorm room!   
UNIX didn't
use HERE IS.

   Mary Ann