| 摘要 |
<p>Exposure and false alteration of data by false access to a memory provided in an LSI is prevented. The program area of a ROM (13) is divided into two by a memory access right. Only when a branch instruction issuance signal from a CPU (12) is detected, an address decode circuit (23) decodes the branch destination address. A mode setting circuit (24) judges to which program area of the ROM (13) the decoded branch destination address belongs, and the applicable mode signal is set. According to the set mode signal, an access control circuit (26) controls the accesses to memories (13, 14, 15).</p> |
