Patent ID: 7213117

Claim:
A 1-chip microcomputer, comprising: register writing control means for determining whether a writing operation occurs from a predetermined address space or from an address space other than the predetermined address space, and outputting a writing reference signal when the writing operation occurs from the predetermined address space; access permission address range setting means for setting an address range within which access by an application program to be executed is permitted only when the writing reference signal is output, such that said access permission address range setting means is operable to set said address range only when a software in a predetermined address space is being executed; judging means for judging whether or not an access is carried out within the address range thus set during execution of the application program; access permission setting means for setting whether or not an access with respect to an address outside of the address range should be permitted, said access permission setting means being operable to set said access only when the software in the predetermined address space is being executed; and control means for controlling an access of the application program to a memory based on a result of the judging means and permission set by the access permission setting means.