the hand calculator, the adding machine,and the punched-card data processing equipment discussed in chapter 4 are all digital devices. On the other hand, the centrifugal switch shuts off a motor when the rotation speed of the shaft (as measured by the angle made with the shaft by weight) becomes too great, may be considered a primitive analog computer. a somewhat more sophisiticated example woule be the cruise control device found in some automobiles. It measures the difference between the electric current generated by the rotation of the wheels anda prescribed constant current. Depending upon this difference, the device adjusts the accelerator so as to maintain the automobile at the prescribed constant speed.