Patent ID: 8209448

Claim:
A data processing apparatus, comprising: an arithmetic circuit that executes a plurality of programs at one of a first operation authority level and a second operation authority level, the second operation authority level being an operation authority level higher than the first operation authority level; and a peripheral device protection circuit that connects to the arithmetic circuit, and that controls access of the arithmetic circuit to at least one peripheral device, wherein the peripheral device protection circuit includes: a first protection preset value including a preset value to specify one of permission and denial of the access to the at least one peripheral device; a second protection preset value set as a protection level higher than that of the first protection preset value, and including a preset value to specify one of permission and denial of the access to the at least one peripheral device; a setting selection circuit that generates access permission/denial information by referring to both the first protection preset value and the second protection preset value when the arithmetic circuit executes access to the at least one peripheral device during a period when the arithmetic circuit operates at the first operation authority level, and that generates the access permission/denial information by referring to the second protection preset value when the arithmetic circuit executes access to the at least one peripheral device during a period when the arithmetic circuit operates at the second operation authority level; and an access protection circuit that receives access information about the at least one peripheral device, the access information output from the arithmetic circuit, and the access permission/denial information, and that determines one of permission and denial of access from the arithmetic circuit to at least one peripheral device, wherein the arithmetic circuit executes a higher authority transfer program prepared in advance during the operation at the second operation authority level so as to change a third protection preset value set as a protection level higher than that of the second protection preset value, and specifying one of permission and denial of the access of the arithmetic circuit to the at least one peripheral device, the arithmetic circuit operating at one of the first operation authority level and the second operation authority level.