Unidentified peripheral in Tektronix PDP-11/20 system

[steven at malikoff.com]

I was idly browsing some old electronics magazines on archive.org and saw this
Tektronix testing system from 1972 that clearly has an 11/20 and TU-56. Just curious
as to what the piece of gear is sandwiched between the two. It sort of looks like a
paper tape reader, but for the two white buttons or whatever they are at the lower right
and the white bit at top right.
It seems to be in a DEC bezel(?) It doesn't seem to match the bespoke Tek gear at right
which looks quite different. I'm guessing it really is just a paper tape reader.

http://www.surfacezero.com/g503/data/4173/Tektronix_S-3260_automated_test_system_PDP-11_20_Electronic_Design_23Nov1972_reduced.png

Thanks in advance.

Steve