[TUHS] terminal - just for fun

[Mary Ann Horton]

I just discovered that Wikipedia has a nice article "teleprinter" that  
goes into detail about these devices.

About "HERE IS" they state this:
Some teleprinters had a "Here is" key, which transmitted a fixed  
sequence 20 or 22 characters, programmable by breaking tabs off a  
drum. This sequence could also be transmitted automatically upon  
receipt of an ENQ (control E) signal, if enabled.[19][20] This was  
commonly used to identify a station; the operator could press the key  
to send the station identifier to the other end, or the remote station  
could trigger its transmission by sending the ENQ character,  
essentially asking "who are you?".

Quoting Mary Ann Horton <mah at mhorton.net>:

> 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
>
> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs
>