1. A MAP detector system including: A. a plurality of Viterbi operators; B. a controller for operating the system in a parallel mode in which the results produced by the plurality of Viterbi operators are used as soft decision data, and in a serial error recovery mode in which the results produced by a selected set of the Viterbi operators are used as the soft decision data; C. a buffer for retaining input sampled data; D. buffer addressing means for controlling the supplying of input sampled data to the plurality of Viterbi operators, the addressing means providing C length sequences of data in the order in which the data are supplied to the buffer to the plurality of Viterbi operators in the parallel mode and to the selected set of Viterbi operators in the serial error recovery mode.