US Patent RE49921 Memory device and controlling method of the same

A memory device includes a memory which has memory areas, and a controller has a first mode and a second mode. Upon receipt of write data, the controller writes data in the memory areas while managing correspondence between logical addresses of write data and memory areas which store corresponding write data. A plurality of the memory areas constitutes a management unit. The controller in the first mode is able to write pieces of data in respective memory areas and configured to maintain data in memory areas in one management unit which contains data to be updated. The controller in the second mode writes pieces of data in respective memory areas in the ascending order of logical addresses of the pieces of data and invalidates data in memory areas in one management unit which contains updated data.