| 摘要 |
<p>PROBLEM TO BE SOLVED: To inexpensively realize a protecting function for protecting the secrecy of ROM(read only memory) data in a one-chip microcomputer only by adding necessary minimum circuit. SOLUTION: The one-chip microcomputer with an interruption control circuit and ROM 12 is provided with a second flag register 212 storing a second permission flag controlling the permission/prohibition of the passage of the interruption request signal of ROM reading and a second gate circuit 222 controlling the permission/prohibition of the passage of the interruption request signal of ROM reading based on the second permission signal. Then, when a priority deciding and vector address generating circuit 23 judges the priority order of the interruption request signal of ROM read from the second gate circuit 222 to be higher than that of present processing and the vector table address of the interruption request of ROM reading is generated, CPU 10 controls the interruption processing of the starting of ROM reading to be executed.</p> |
