Apparatus for validating a card having positioned thereon a plurality of redundant encoded blocks of data readable by moving the card past a reader and for controlling the movement of such a card whose validity is to be determined. A card transporter moves a card along a predetermined path. A reader senses each block of data on the card as it moves forward along the path from an entry position to a dwell or escrow position and supplies an electrical signal representative of the data in each block. A card validator responsive to this signal compares data derived from at least one block thereof with a preselected set of data in making the validity determination. The validator includes circuitry for combining the data from at least one block with a prior set of data to produce a stored resultant set of data, and for comparing it with a preselected set of data and for supplying an indication of card validity if these sets of data are identical. If the card is not determined to be valid, the card transporter returns it to the entry position. A valid card remains in the escrow position pending either subsequent collection thereof or the return thereof.