[GreenKeys] Stunt Box

[Jim Haynes]

And then there is the machine called the Model 28 Sequential Selector,
which is a Model 28 printer that is missing all the typing parts and
exists only to have a stunt box.  That took the place of the SOTUS from
the Model 15 line, which was likewise a machine that could recognize and
respond to a character or sequence of characters by closing a contact.

In many cases the 28 printer with a stunt box did all the sequential
selection necessary, so it replaced a Model 15 along with a SOTUS.
The F.A.A. was a big user of this kind of stuff, using a received
station's callsign, usually the three-letter airport code, to trigger
transmission of a weather report from that station.  Also to
have a printer print only the messages addressed to that station.

The trouble with using a 28 printer this way was that if the printer
broke you couldn't just plug a spare printer into the loop; you also
had to transfer all the wires connected to contacts on the stunt box.
So the F.A.A. went from a small box with a 6x6 array of pushbuttons
to a set of panels that filled a whole relay rack.