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
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) [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.


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