[GreenKeys] Ticker-tape first unveiled 1867

[Harold Hallikainen]

> Yes, the history of printing telegraphy up to Baudot, and continuing for
> some time after, involved type wheels with one pulse for A, two for B,
> three for C...  Baudot invented the efficent binary encoding, but it was
> not until the circa 1930 Teletype ticker that such a code was used for
> stock ticking.  And after that the old tickers continued to be used for
> stuff like baseball scores.
>
> The final Teletype ticker used the aggregate motion principle that was
> used in the Model 37 page
> printer.______________________________________________________________

I can imagine a "daisy wheel" type printer. Using something similar to a
Strowger switch, a pulse would advance the wheel to the next position. A
pause would trigger the print hammer and reset the wheel. I did a bunch of
stuff with Strowger switches in high school. The standard telephone
selector unit had an A relay that detected loop current, and a slow
release B relay that would differentiate between dial pulses and on-hook.
I can imagine a telephone dial that could send out up to 30 or so pulses.
As mentioned above, the wheel would advance on pulses and print and reset
on a pause in pulses. However, I've read that they did not necessarily
reset but, instead, sent the number of pulses required to advance from the
current character to the next. Once you lost sync, you got garbage. So,
they'd send a sync character that was more than the allowed number of
pulses. This would reset the print wheel. I don't think the average print
speed would be any better using the "delta" coding over sending the whole
character count every time, so I don't know why they did not send the
whole character count every time and then print and reset.

In the 1980s, I had a VERY HEAVY daisy wheel printer that was "smart." It
would turn the wheel in the shortest direction to get to the next
character. That may have been a bit much for 1870.

Harold




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