I wrote:
  I'll have to open up my PDP-11/83 tonight.  Its
TK50 will stream while
 writing, as long as what's being written can be read reasonably fast
 from (RQDX3/RD54) disk.  The TQK controller is sitting right up at the
 top end of the Q-bus, to get high priority -- but I don't know if it's a
 TQK70.  I've really just assumed it's a TQK50 without thinking too much
 about it... 
Turns out it's an M7546; a TQK50.  I guess I'll get streaming writes
more often with an M7559 (TQK70) than I do at the moment, then.  :)
-tih
--
Most people who graduate with CS degrees don't understand the significance
of Lisp.  Lisp is the most important idea in computer science.  --Alan Kay