Abstract: When data is written into a memory card 1, if a write command and data are transferred from a host device 2, a memory controller 4 writes the data into an erased optional block. When the write operation is finished, the host device 2 transfers a second write command and data. The memory controller 4 judges whether a last address of the first transferred data and a head address of transfer data set by the second write command are continuous or not; and continuously writes, when the addresses are continuous, the second transfer data subsequently to the first data. And, when the data write operation is finished, a copy processing is carried out.

Abstract: Blocks and clusters are brought to correspondence thereby to erase blocks of memory area efficiently. A flash memory has its physical addresses partitioned from address 0h sequentially into blocks each having eight sectors. The data area of logical address starts at address 4Dh, which is set to the starting physical address 50h of the block which is close to the top of data area, and the data area is set sequentially to the following physical addresses. The remaining logical addresses 3D7Dh-3D7Fh are brought back to the top of physical address and set to physical addresses 0h-2h. Consequently, clusters (a cluster has 4 k bytes or 2 k bytes) of data sent from a host unit correspond to blocks of physical addresses, enabling block erasure of the flash memory, whereby the number of times of erasing operation at data writing can be reduced significantly.