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From: morris@jade.jpl.nasa.gov (Mike Morris)
Newsgroups: comp.dcom.telecom
Subject: Re: The 'Public Telegraph Office'
Message-ID: 
Date: 25 Sep 89 08:58:58 GMT
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johnl@esegue.segue.boston.ma.us (John R. Levine) writes:

>In article  you write:
>>typing. A small bell, driven by a  just like today ...

>Smallest nit of the week -- telex machines are all Baudot five-bit code,
>for which there's no such thing as a control key, just letter-shift and
>number-shift.  The bell is some number-shift key.

>[Moderator's Note: Well I believe it was the 'shift - 7' now that you mention
>it; and of course control-G is Ascii 7. Weren't the 'number-shift' keys
>essentially like control keys? How did they get line feed, carriage return,
>ENQ (who are you?) and answerback without control codes?  My handy Ascii
>chart here says control-E, or ASC(5) when sent polls the other end to

This isn't ascii!  7-bit ascii has 128 combinations, we have 5 bits with
32 combinations.  Like they say in Oregon: "Things are different here!"

>identify itself. What do you think?  PT]

Here's the map of the baudot / 3-row / pick your name..

    1 2 3 4 5 6 7 8 9 0   The upper case is the same in all character sets
    Q W E R T Y U I O P   for this row of the keyboard.

     -   $ ! &   ' ( )
     A S D F G H J K L

      "  /  :  ;  ?  ,  .
FIGS  Z  X  C  V  B  N  M  LTRS  LF  (blank)

         (space bar)


There is actually four different US character sets, plus the international set.
There is the "Military", the "Weather", the "TWX" and the "Telex" set.

LTRS    Int'l    Mil   TWX   TELEX   WX
 A        -       -     -      -     up arrow
 S        '       Bell  Bell   '     Bell
 D       currency $     $      WRU   upper right arrow
 F       DV*      !     1/4    $     right arrow
 G       DV*      &     &      &     lower right arrow
 H       DV*      STOP  DV*    #     down arrow
 J       Bell     '     ,      Bell  lower left arrow
 K       (        (     1/2    (     left arrow
 L       )        )     3/4    )     upper left arrow
 Z       +        "     "      "     +
 X       /        /     /      /      /
 C       :        :     WRU    :     circle
 V       =        ;     3/8    ;     circle with a vertical bar inside
 B       ?        ?     5/8    ?     circle with a + inside
 N       ,        ,     DV*    ,     circle (my chart dupes shift-C)
 M       .        .     .      .     .

DV* means "Domestic Variation"

My first machine was purchased from Southern Pacific, and had the "TWX"
character set - commonly knowin in ham circles as the "stock market" set.
Fortunately the Model 15 and 19 printers had a type basket with soldered-on
type pallets, and I was able to purchase replacement pallets (for 30 cents
apiece!) and solder them on.  Changing the shift-J bell to a "S-Bell"
required disassembling the machine and replaciing the decoding arm.
Interestingly, breaking off a tab allowed printing a bell character (like
the " were translated into strings
like fortrans ".LT." and ".GT." - he had implemented .NE. for <>, etc.
I was amazed that it could be done, and flabbergasted that he did it in
a 8k system (note that 8k was the total RAM - which held the system, the
I/O lookup and the BASIC interpreter!).

I wish I had saved a copy of the I/O driver listing.

Mike Morris                      UUCP: Morris@Jade.JPL.NASA.gov
                                 ICBM: 34.12 N, 118.02 W
#Include quote.cute.standard     PSTN: 818-447-7052
#Include disclaimer.standard     cat flames.all > /dev/null