Abstract: A data detection system and method for a bubble memory is disclosed in which the memory is operated in a start-stop mode during reading of data stored in two separate major loops which are stepped concurrently and wherein each major loop comprises interleaved data and no-data cells. The field rotation is controlled so that if the read operation is stopped, a no-bubble cell of each major loop is stopped adjacent the magneto-resistive sensor which provides read data signals to the detector of that major loop. The detector involves a detection cycle comprising a reference portion and a data portion. The signal generated during the data portion is integrated and compared against the integrated value of the signal generated during the previous reference portion. The comparison of two integrated values, one from a data cell and one from a reference cell, produces different results depending on whether a bubble or no-bubble was stored in the data cell.