PURPOSE: To store/read out a data string shorter than data bus width in/from a memory at the largest density without increasing load on a device body in a memory card capable of freely attaching a storage device from a game device body and carrying it.

CONSTITUTION: A bit segmenting means 2 is arranged between a memory 1 and the device body 3. The memory card 8 is provided with an oscillation circuit for generating a reference signal independent of the body 3. An address/ control signal 6 outputted from the body 3 is inputted to the means 2. An address/control signal 4 is outputted from the means 2 to the memory 1 and memory data are read out. The memory data 5 inputted to the means 2 are processed by prescribed bit processing and then outputted to the body 3 through a data bus 7. The bus 7 is used also for writing from the body 3 to an internal register in the means 2.