I always though QIC was an abbreviation for Quarter
Inch Cassette. I'm = 
I heard 'Quarter Inch Cartridge', but it makes little difference.
  fairly sure I've used DC300s and they were
cassettes full of quarter =
 inch tape with a constant peripheral speed drive band inside so no need =
 for variable speed spool motors. 
The ones I use on my PERQ (with an Archive Sidewider QIC11 drive)
certainly are...
-tony