Patent ID: 6972979

Claim:
A nonvolatile storage device comprising: a plurality of external terminals; a controller; and a nonvolatile memory, said controller controlling storage operation of data inputted from said external terminals to a region designated by said nonvolatile memory depending on control information inputted from any of said plurality of external terminals, wherein the nonvolatile storage device includes: a plurality of external data terminals to which a data signal is inputted; pull-up circuit for pulling up the external data terminals up to a power source voltage; level detection circuit for detecting a potential of said external data terminals; and a data transfer circuit for selectively fetching the data signal inputted to said plurality of external data terminals and then transferring the data signal to an internal circuit as data of a predetermined bus width, and wherein said level detection circuit detects a potential of a predetermined terminal of said plurality of external data terminals when said control information is inputted, and said data transfer circuit determines said bus width depending on a combination of potentials of the predetermined external data terminals.