Patent ID: 8291124

Claim:
A semiconductor device including a data processing unit, the device comprising: an external interface circuit which controls access to an address space of the data processing unit from outside the semiconductor device, wherein the external interface circuit includes: an external terminal arrangement which inputs, from outside the semiconductor device, a part of an address signal used to access the address space; a supplementary register in which supplementary information for supplementing an upper portion of an address information that has been input from the external terminal is written from outside the semiconductor device; a mode register in which mode information is written from outside the semiconductor device; and an address control circuit which generates an address signal to access the address space in a form based on information from the external terminal arrangement, the supplementary register, and the mode register, wherein the form of the address signal generated by the address control circuit includes a first generation form which supplements the address information input from the external terminal arrangement by the supplementary information of the supplementary register, and wherein the external terminal arrangement includes an external multiplex terminal and an address input terminal used for address input or data input/output in a switching manner, and inputs, in the first generation form, address information using both the address input terminal and the external multiplex terminal.