Abstract: A positional encoder which provides absolute position information from a single code track. A chain code track is positioned on a code disk to supply position words of N consecutive bits, each position word being unique and corresponding to a different position of the code disk. Means are provided for detecting the elements of the chain code as the code disk is rotated with respect to a fixed point. The position data are accumulated in the order received and N consecutive bits are examined to determine the position to which the bits correspond.