Abstract: A finite impulse response (FIR) filter and a Viterbi detector system for a magnetic read channel are disclosed. The FIR equalizer generates equalized sampled outputs to the Viterbi detector system. The Viterbi detector system determines the most probable value of all references, R.sub.i by accumulating a summation of data sample values, D.sub.t, for selected legal bit sequences over a significant amount of random data. The summation and count of data samples are output to a system microprocessor for calculation of an average reference for each path of the Viterbi system. The Viterbi detector system also calculates, in real time, magnitude of differences between the output data received from the FIR equalizer and transition references for each data sample to generate transition metrics, adds transition metrics to state metrics from the source node of two paths, and compares the result. The lesser of the two results yields the most likely correct state metric.