A non volatile memory device includes a first buffer register configured to receive and store the data to be stored into the memory device provided via a memory bus. A command window is activatable for interposing itself for access to a memory matrix between the first buffer element and the memory matrix. The command window includes a second buffer element that stores data stored in or to be stored into a group of memory elements. A first data transfer means executes a first transfer of the data stored in the second buffer register into the first buffer register during a first phase of a data write operation started by the reception of a first command. A second data transfer means receives the data provided by the memory bus and modifies, based on the received data, the data stored in the first buffer register during a second phase of the data write operation started by the reception of a second command. The first transfer means execute a second transfer of the modified data stored in the first buffer register into the second buffer register during a third phase of the data write operation. The second transfer is executed in response to the reception of a signal received by the memory bus together with the second command.