Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!bellcore!texbell!vector!telecom-gateway
From: tanner@ki4pv.uucp (Dr. T. Andrews)
Newsgroups: comp.dcom.telecom
Subject: Re: The 'Public Telegraph Office'
Message-ID:
Date: 29 Sep 89 00:35:25 GMT
Sender: news@vector.Dallas.TX.US
Organization: CompuData, Inc. (DeLand)
Lines: 61
Approved: telecom-request@vector.dallas.tx.us
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@vector.dallas.tx.us
X-TELECOM-Digest: volume 9, issue 416, message 2 of 6
) [Moderator's Note: Well I believe it was the 'shift - 7' now that
) you mention it;
There is no "shift-7" in baudot code. The figure '7' is on the
"shifted" character set (same character code as the letter 'U',
0b00111). The had the same code as the letter 'J' (0b01011).
) Weren't the 'number-shift' keys essentially like control keys?
Presuming that you mean the "shift" (FIGS) and "unshift" ("LTRS")
keys, no, they weren't like control keys. They differed in two
important ways. First, they sent character codes. Secondly,
they had no printing effect themselves, but caused later
characters to be printed from a possibly different charset.
) How did they get line feed, carriage return,
There are baudot codes for CR and LF. These, interestingly
enough, are effective in both shifted and unshifted modes.
) ENQ (who are you?)
You typed "WHO DAT?" and stopped typing.
) and answerback without control codes?
The other guy typed "IT'S ME." in response.
He might have had a tape reader in which case he could have this
text prepared for your editfication; it would save him typing it
again.
) My handy Ascii chart here says control-E, or ASC(5)
It should be noted that ASCII is not a 5-level code. When
discussing the 5-level devices, refer not to your ASCII chart but
to a BAUDOT chart instead.
) What do you think? PT]
I think that you haven't worked on many 5-level devices, to be
honest. These slow devices (noisy, too) are pretty much
unrelated to any modern computing needs. I only ever heard of
one general-purpose computer system which purported to support
the things, and never actually saw it done.
Please see the [Radio Amateur's Handbook] for information on
the BAUDOT code. You might also consult a maint manual for a
model 15/model 19 teleprinter.
The original wiring on these devices is somewhat baroque.
Considering that very little of it is actually needed (a common
maint trick is to remove the old wiring, add the 10 or so wires
needed in the whole device, and try to figure out what to do with
the many, many feet of old wire. It has been thought that
perhaps the added wiring was for the military - whether to
confuse the enemy, or just to raise the price, has not been
determined.
The characters in the FIGS set, by the way, were somewhat
variable depending on the particular unit in hand. On some, you
could get motor stop instead of one of the printing characters (I
think that you might have been able to configure which you got).
On others, you might not have the prime ('). Other units had
weather symbols instead of some of the figures.
...!bikini.cis.ufl.edu!ki4pv!tanner ...!bpa!cdin-1!ki4pv!tanner
or... {allegra attctc gatech!uflorida uunet!cdin-1}!ki4pv!tanner