[GreenKeys] Teletype M12 KSR

[Jim Haynes]

On Fri, 23 Jan 2015, Jack wrote:

> Just think...if Teletype had succeeded with the Intronix, maybe all of the printers
> we use today would say "Teletype" instead of "HP"!

I've heard people say that Teletype had the first ink jet printer - which
was true, but Inktronic had nothing in common with the later generation of
ink jet printers.  Inktronic used high-voltage electrostatic deflection
of ink droplets to form the characters.  The electrodes were out in the 
air in front of the paper, so they tended to attract paper dust (high
voltage electrostatics, remember) and that distorted the printing.  And
attempts to keep them clean usually resulted in a certain amount of
bending.  So the print was legible when the machine left the factory
but went downhill from there.  Would take an expert tuner to actually
improve print quality.

The HPs and others use an entirely different technology, somewhat related
to thermal printing in that micro heaters can be used to blast ink
droplets onto the paper.

>
> The DX reader used wire sensing pins and they constantly got gunked up, out
> of alignment, or even bent. They weren't made to read chadless tape from
> Model 14's, I'm sure!
>
No, they were developed as a strictly high-speed reader to replace the CX,
which was limited in speed because of its mechanical complexity. 
Meanwhile the computer industry and others were using photoelectric 
readers to get very high speed.  These had various problems, such as
inability to stop on-character and transparency or reflectivity of tape.

> The 14 TD's on our TTY tables were the standard variety. There was a 7 foot
> cabinet at every service order office that had a "SOTUS" sequence selector to
...
> need for the sequence selector. I never saw one of those things 
break.

I have a couple of them that don't work quite right, but I haven't tried
very hard to fix them.  Believe the original application for the SOTUS was
the 81-type automatic switching systems, where they made it possible
for stations on a multi-station line to copy only traffic intended for
them, and to respond to transmitter start codes.  Then they were used
by the CAA/FAA to start automatically the readers sending in weather
observations.  The M28 stunt box took over that function, but added a
new problem.  When your M28 breaks you can't just switch in another
machine to the loop; you have to switch all that stunt box stuff that
operates contacts.  The SOTUS was also used for things like remote control
and sensing of pipe lines.