Dan Weatherall has release a free sound pack, Pack Three, sampled from a Casio CT-647.
Pack Three contains 20 preset drum loops, sampled straight from the Casio CT-647 home keyboard.
Also included in the pack are one shot samples of the kick drum, snare drums, high hats and cymbals, so you can create your own drum loops and patterns.
All the loops are in .REX format for use in Reason’s Dr. Rex player.