We never used those particular devices at our
installation, but I did see
some info on them (I think there was also a 7184 of similar nature).
These were synchronous, block transmission terminals - a screenful of
information was sent at a time (either system -> terminal or terminal ->
system). Used on the 1900 series and perhaps 2900s. Normally
connected via a
7900 series communications processor (better known as a PF56), but some of
the last smaller 1900s (1901T & 1902T) had a built-in adaptor.
When I first started work as an Op for the local council they'd just phased
out their old mainframe (I was sure it was a 2900 but could've been a 1900)
and upgraded to a dual node 2966. The old console had one of these keyboards
so that matches. The comms cable on this keyboard is massive AND it includes
240V mains.
I'll keep digging :)
w