| 摘要 |
PURPOSE: To prevent the unapproved copying of an unapproved user by providing a circuit for detecting that a code is accessed by a sequential order which is not a normal non-sequential order. CONSTITUTION: A go-by flag 103 corresponding to a pre-branch address array 102 is set when the pre-branch address of the array 102 is accessed. That is, in a branch address array 104, an address to be accessed after the pre-branch address is accessed in normal non-sequential access and to be accessed before the access of the pre-branch address in simply sequential access is stored. A comparator circuit 107 checks whether or not valid access is performed by the flag 103 of the array 102 every time the address in the array 104 is accessed, and when it is not performed, instructs an error function generation circuit 110 and turns output data from a ROM 109 to incoherent data. |
