Disk drive capable of rereading same signal from disk in case of error in read signal

摘要

A parameter value is set in a register. A signal is read based on the parameter value. When an error is recognized from an MSE value calculated by a Viterbi decoder, the parameter value is changed and the signal is reread. A new parameter value is calculated based on a change value by which the parameter value is changed and the MSE value. The new parameter value is stored in the register. Thus, an error rate can be converged as a result of the retry.