[GreenKeys] shockingly basic question - Teletype Model 33 ASR

[Mike Douglas]

If you select 8 bit with mark parity on your terminal server, you’ll probably get the 8N2 timing the Teletype requires (the mark parity bit serves as the first stop bit).

Mike

> On Jan 31, 2021, at 7:11 PM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
> 
> 
> Thanks guys for the responses - a lot of great info for me to digest!  
> 
> My terminal server (Equinox ELS-16) allows me to define character size as 7 or 8 bits, and to set parity as NONE, ODD, EVEN, MARK or SPACE. 
> 
> I don't seem to have the ability to specifically state the number of stop bits, however.
> 
> Anyway.. I'm going to crack my Teletype open and confirm exactly what's going on.
> cheers!
> Andy 
> 
>> On Sun, Jan 31, 2021 at 5:43 PM Keith Lueck <kwlueck at swbell.net> wrote:
>> Jim & Wayne are spot-on, of course.  I learned the hard way that you best include the parity bit - even though the 33 doesn't give a whit about parity...  
>> My machine was occasionally producing errors when I was feeding it 7 N 2.  Wayne Durkee set me straight, and, viola, when I sent it 7 M 2, everything was 100% ducky.  
>> 
>> On Sunday, January 31, 2021, 03:32:30 PM CST, Jim Haynes <jhhaynes at earthlink.net> wrote:
>> 
>> 
>> All the 33s and 35s generate 11 unit code.  1 start bit, 7 data bits, one
>> bit which may be even parity or may be marking, and two stop bits.  That's
>> where 110 baud comes from. 100 wpm = 10 chars/sec and each char contains 
>> 11 bits.  The reason for two stop bits is the difficulty of making a
>> mechanical selector that is reliable at 100 wpm.
>> 
>>     ---
>> 
>>     "Ya can argue all ya wanna, but it's dif'rent than it was."
>>     "No it ain't! No it ain't!  But ya gotta know the territory."
>>         Meredith Willson, The Music Man
>> 
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