Weren't they driven via a current loop with 5-level baudot?
At 12:19 PM 2008-03-18 -0800, you wrote:
David Griffith wrote:
A big part of my involvement in classic computers
comes from a fascination
for antique machinery. For instance, I'm fascinated by old glass-domed
stock tickers. Now, I can buy an exacting reproduction for some $25,000
or $3,000 from the
stocktickercompany.com. That's way too pricey for me,
so does anyone here know where I can get a fixer-upper?
..tres cool.
Going from their history pages, South America might be a better bet for an
original:
".. It has also been reported that during World War II many of the
Universal
and self-winding tickers were scrapped for metal or sold off to businesses
in South America."
".. In 1960, Western Union ordered all these remaining tickers destroyed"
Does anybody know what the signalling technique (protocol) for these devices
was? I've always been curious about this but never had a mechanism to peruse.
My recollection from readings is that async bit-serial devices (tty, baudot
codes & c.) ("automated telegraphy") were not really successful until into
the 20th century, while these stock ticker networks were functioning decades
before that.
Looking at the photo gallery on the site and the apparent simplicity of the
mechanism, I'm guessing it was just a series of pulses to increment/rotate the
print wheel to select the character, followed by a pulse for a print
hammer and
to advance the tape. There would then be the question of whether it was
separate circuits for the increment and print solenoids or whether there
was some
mechanism perhaps to separate an increment command from a print command
sent over
one circuit (such as shorter vs longer pulses).
Technically, the other half of the system (sending/encoding equipment)
would be
just as interesting, but like some early fax equipment I have, where there
was a
similar one-to-many relationship, only a few of the many survive and
next-to-none,
if any, of the 'ones' have survived.
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