[GreenKeys] Jack Selection for TTY equipment

[Jim Haynes]

On Fri, 15 Nov 2013, hwhall at compuserve.com wrote:

> If interested, I have in my stuff a couple of vintage 1/4 inch teleprinter
> plugs with red and black colored shells. They came off some old Teletype
> stuff we played with when I was in college at our college industrial arts
> department ham station.
> 
"And therein lies a tale..."

In U.S. military and Bell System practice the plug with the red shell
is the printer, and the one with the black shell is the keyboard.  In
Western Union equipment it's exactly the opposite.