[GreenKeys] Asr33: How are BREAK encoded ?

[Wayne Durkee]

Keith,

Thanks for that reminder of the TWX Break button. It stops the tape at the sending TWX. I cant remember but it was on the cover plate right?

The AB drum was coded in both ASCII and Baudot machines for TWX and Telex with an abbreviation of the machines business name and city it was in. Uncoded as most computer 33's were it will give you a tape leader of 20 blanks or nothing punched but the feed wheel.

If you are using a 32 for RTTY, you should disable the vertical pawl that allows the machine to start the AB 20 character function. If you are receiving garble and catch a FIGS D, the AB will trip and the next 20 characters will be garble even if the received garble has stabilized.

Wayne
KB1FDW


> On February 21, 2017 at 1:09 PM Keith Lueck <kwlueck at swbell.net> wrote:
> 
>     According to the BSP that Don House provided to me, the 101C dataset converted the break signal into a ~200 msec spacing tone (regardless of how long the "BREAK" key is pressed) which interrupts the transmission of characters at the sending end.  At the sending end, the "BRK RLS" light goes on, and transmission is stopped until "BRK RLS is pressed...  
> 
>     Keith
> 
> 
> 
>     ---------------------------------------------
>     From: Wayne Durkee <teletypeparts at comcast.net>
>     To: GREENKEYS BULLETIN BOARD <greenkeys at mailman.qth.net>; "Jones, Douglas W" <douglas-w-jones at uiowa.edu>; Julien Scrofani <julien.scrofani at gmail.com>
>     Sent: Tuesday, February 21, 2017 11:41 AM
>     Subject: Re: [GreenKeys] Asr33: How are BREAK encoded ?
> 
>     I am not a computer guy, but Break is something used with your computer, not the Teletype although TWX machines had a Break key, but I have forgotten what it was for.
> 
>     Wayne
> 
> 
>         > > On February 21, 2017 at 6:31 AM Julien Scrofani <julien.scrofani at gmail.com> wrote:
> > 
> >         Hi guys,
> > 
> >         Thank you for your responses.
> > 
> >         The start and stop units are not parts of the punched code on the tape, right ?
> >         How then, when I read the tape, does the adapter convert these sequences into BREAK sequences ?
> > 
> >         Julien
> > 
> >         Le mar. 21 févr. 2017 à 05:05, Jones, Douglas W <douglas-w-jones at uiowa.edu mailto:douglas-w-jones at uiowa.edu > a écrit :
> > 
> >             > > > From: Julien Scrofani [julien.scrofani at gmail.com mailto:julien.scrofani at gmail.com ] Monday, February 20, 2017 2:09 PM
> > > 
> > > 
> > > 
> > >             > I taped several BREAK sequences with the tty puncher, pressing my finger more or less time on the key.  The punched codes differ a lot (see pic). When I read the tape, toward my terminal via the usb current loop adapter, all BREAK are correctly converted.
> > > 
> > >             Are they coded with several bits patterns ? If not, how are they interpreted correctly by the adapter ?
> > > 
> > > 
> > > 
> > >             The adapter recognizes break by the lack of a stop bit at the end of the character, not by the bit pattern.
> > > 
> > > 
> > > 
> > >                             Doug Jones
> > > 
> > >                             jones at cs.uiowa.edu mailto:jones at cs.uiowa.edu
> > > 
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