| 摘要 |
PURPOSE:To prevent runaway of a software caused by breakdown of a program area, by inhibiting the write to a write access inhibiting bit area, when a write access inhibiting bit is set in this inhibiting area. CONSTITUTION:First of all, a write inhibiting bit is written in a write inhibiting bit area 12 of a program area 10 and a data area 11 from a write inhibiting bit writing circuit 20. Subsequently, when a write request to a designated address by address information ADD is executed, this information ADD is provided to a main storage device 1 and a write instructing signal W is applied to a write inhibiting gate 22. When logic 1 is set in the area 12 of this designated address, a read-out bit R is provided to the gate 22, and the gate 22 outputs the logic 1 to the area 12, therefore, write to its designated address is inhibited. In this way, generation of a program bug is prevented, and accordingly, runaway of a software can be prevented. |
