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'[OT]: Baud rates'
2000\08\16@131327 by Bob Ammerman

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ASCII TTY's were usually 110 baud. This gave them 10 CPS bacause they used
an 11 bit word (2 stop bits). They used current loop and required a
hard-copper connection from one end to the other.

When modems came out, which allowed transmission over normal AC coupled
phone lines, they started at 300 baud (30 CPS with one stop bit), exactly 3
times faster.

As modems improved they always seemed to stick to powers of 2 improvement
over that (with a few exceptions like the 75/150 BPS back channel in teletex
and Bell 202).

The 'really high rates' like 57,600 and 115,200 are small integer multiples
of 19,200, which is 2^6 * 300.

There were some funny cases like 1800 and 3600 baud thrown in to fill in the
gaps.

For a really wierd rate try the one used by terminals based on the IBM
selectric mechanism: 134.5 baud. This had to be related to the physical
speed of the existing typewriter mechanism.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
sofftware)


{Original Message removed}

2000\08\16@134644 by Barry Gershenfeld

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>ASCII TTY's were usually 110 baud. This gave them 10 CPS bacause they used
>an 11 bit word (2 stop bits). They used current loop and required a
>hard-copper connection from one end to the other.
>
>Bob Ammerman

I was waiting for this to go [OT].  What you say about the TTY's is
true, and before that, the prehistoric models (the ones you used to
hear on the Nightly News) went 60 words per minute.  A "word" was
considered to be 5 characters plus a space.  The point is that by
the time anyone ever cared about the term "baud", this stuff was
long in existence.  The only reason we can say the thing was 45
baud was because we went back and calculated it.

Baud and bps were interchangeable until we got to 1200 bps.

Barry

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2000\08\16@140347 by Severson, Rob

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face
I feel an urge to mention that I once owned a Lear-Seagler (sp?) dumb
terminal that had 75 baud and I think half that (37.5!) as the low settings.

Perhaps my memory isn't what it ... what was I saying?


> >ASCII TTY's were usually 110 baud. This gave them 10 CPS
> bacause they used
> >an 11 bit word (2 stop bits).

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2000\08\16@142832 by W. K. Brown

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Just for the record, I've seen those too. (all multiples of 75 b/s).
Keith

       -----Original Message-----
       From:   Severson, Rob [SMTP:spam_OUTseversonTakeThisOuTspamJGED.COM]
       Sent:   Wednesday, August 16, 2000 2:15 PM
       To:     .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
       Subject:        Re: [OT]: Baud rates

       I feel an urge to mention that I once owned a Lear-Seagler (sp?)
dumb
       terminal that had 75 baud and I think half that (37.5!) as the low
settings.

       Perhaps my memory isn't what it ... what was I saying?


       > >ASCII TTY's were usually 110 baud. This gave them 10 CPS
       > bacause they used
       > >an 11 bit word (2 stop bits).

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2000\08\16@161219 by Chris Carr

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Back in the days when data transmission was real data transmission (I had
hair down to my waist, British Post Office Telephones Data Terminals (Creed
7B) required 2 men to lift it, and television was only available in one
colour (monochrome) the east side of the pond use 50 baud (asynchronous, 1
start bit, 5 data bits, 2 stop bits), the other side used 45.5 baud and I
built my first computer (Analogue).

Nostalgia..... It's not what it used to be.

Regards
Chris

{Original Message removed}

2000\08\16@171001 by Barry Gershenfeld

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>Back in the days when data transmission was real data transmission (I had
>hair down to my waist, British Post Office Telephones Data Terminals (Creed
>7B) required 2 men to lift it, and television was only available in one
>colour (monochrome) the east side of the pond use 50 baud (asynchronous, 1
>start bit, 5 data bits, 2 stop bits), the other side used 45.5 baud and I
>built my first computer (Analogue).
>
>Nostalgia..... It's not what it used to be.
>
>Regards
>Chris

And if you bought a TTY and it was British it ran 66 WPM but you
could pull the gears off and get 60 WPM gears to put on so it
would run "right".

My first TTY printed on a long strip of paper.

Barry

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2000\08\16@184247 by Harold M Hallikainen

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On Wed, 16 Aug 2000 21:08:21 +0100 Chris Carr <nyedspamKILLspamBTINTERNET.COM>
writes:
> Back in the days when data transmission was real data transmission (I
> had
> hair down to my waist, British Post Office Telephones Data Terminals
> (Creed
> 7B) required 2 men to lift it, and television was only available in
> one
> colour (monochrome) the east side of the pond use 50 baud
> (asynchronous, 1
> start bit, 5 data bits, 2 stop bits), the other side used 45.5 baud
> and I
> built my first computer (Analogue).
>
> Nostalgia..... It's not what it used to be.

       I remember my old model 15 printer and 14 TD and typing reperf ran at 60
wpm. The start and data bits were 22 ms while the stop was 31 ms (if I
recall correctly). This was later changed to 1.5 stop bits in UARTS (like
the old AY5-1013).

Harold



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