From: David Griffith <dgriffi at cs.csubak.edu>
 Does anyone know what sort of interface the AT&T 3b2 uses for its mouse?
 I found one which is missing its mouse.
  
I've never seen a 3b2 with a graphics display.  While I've seen an awful lot
of 3b2s (AT&T carpet bombed Gatech with them in the mid-80s), that doesn't
mean there wasn't one.
Do you perhaps mean the AT&T Blit family of graphics terminals
(Jerq/Blit/5620/630/730) that were often serially attached to 3b2s?  If so,
http://www.brouhaha.com/~eric/retrocomputing/att/5620/5620_faq.html should
be a start, as well as any surviving archive of comp.terminals.tty5620.
These things are nifty.
Ken