[GreenKeys] do the length of stop bits affect clutch wear?

[Jim Haynes]

On Fri, 23 Nov 2018, Duncan Brown wrote:
> At some point in the mid 1960s, both Teletype Corp & KLI started  supplying 
> TTYs with 7.00 code transmitters to the military. Some KLI machines were set 
> up for 8.00 from the keyboard and 7.00 from the tape reader. Was this for 
> AUTODIN, or some other computerized system that couldn't handle the

I don't know.  Since AUTODIN was a Western Union job, perhaps W.U.
specified 7.00 code.  Prior to AUTODIN the Air Force had W.U. Plan 55.
Very likely that system used 7.00 code as well, but I don't know.

Prior to AUTODIN the crypto people for some reason found it necessary
to control the rate of character emission from all the TTY sending
devices.  In the Model 28 parts books you'll see sets of parts to adapt
keyboards to "synchronous pulsed operation".  Sometime in the 1970s I
bought 3 racks of equipment at a surplus sale.  Two of the racks held
regenerative repeaters, and the other held what were called TD pulsers
which simply generated pulses at the character rate to pulse the sending
devices.  Beats me why those smart people in the crypto agency couldn't
accomodate the natural output of keyboards and tape readers.

Another crypto mystery, a little older, concerns time-division multiplex.
The multiplex has to send slightly fast so that it never falls behind the
characters coming in, since it has no ability to store characters that
might overrun it.  As a result the mux receiver puts out characters
with slightly short stop pulses, and then about every 50 characters there
is a pause when it gets ahead of the incoming stream.

For some reason the crypto machinery doesn't like this, so in 1956 there
was published a paper on a "Printing Telegraph Signal Normalizer" built
by W.U. which would turn the mux output into a stream of uniform 
characters.