 The DP70 as shipped from the factory was equipped for dual speed operation, at 24fps (the frame rate at which almost all 4/35 prints with a combined soundtrack are projected) and 30fps, the frame rate used in the original Todd-AO system.The original version of the DP70 used separate drive motors for 24fps and 30fps operation, whereas the AAII had a single motor and a dual locking pulley mechanism on the main drive shaft to change the speed of the mechanism.There were also several other more minor changes in the AAII.