[GreenKeys] Teletype Trivia

[jhhaynes at earthlink.net]

On Wed, 27 Jul 2005, riceguy wrote:

> What was the middle position earmarked for on a 28RO keyboard between the CR 
> and LF keys?
>                          Mine has a hole and it is filled with a factory 
> cover plate

On selective calling machines (principally for FAA) there was a toggle
switch in that position labeled LOCAL-REMOTE.  The switch operates a
solenoid on the left side of the machine that overrides print suppression.
Overriding it allows the machine to print everything that comes in,
regardless of selective calling.  LOCAL energizes the solenoid.
REMOTE allows it to be energized remotely, but I don't know if that
ever happened.

I believe the application is this:  at FAA stations they wanted to be
able to switch printers among various services.  Selective calling is
used in Service B, which is for flight plans, so that the station copies
only traffic addressed to it.  In Service A, which is weather, they want
to copy everything on the circuit.

Later on there were other things used in that hole, such as a button
or switch to silence alarms.