| 摘要 |
PURPOSE:To prevent the formation of an infinite loop by detecting the number of times of reinterruption when the reinterruption is generated by a trouble in a single system, and if the number of times reaches to a prescribed value, inhibiting the reinterruption. CONSTITUTION:Restart counting start and end addresses are previously stored in registers (a), (b), respectively. Comparators 1, 2 compare the counted value of program addresses in executing in a program counter PC with the values stored in the registers (a), (b). If a trouble is generated, the program address in executing coincides (1) with the restart counting start of the register (a) and a signal is sent to an FF3. The Q output of the FF3 is sent to an AND circuit 4, and simultaneously a restart signal RS is inputted to the AND circuit 4. The output of the circuit 4 is counted up 5 by ''1'' and inputted to a comparator 7. When the value reaches the prescribed number of times of a register 6, an iPL signal is generated. If the contents of the program counter PC coincide with that of the register (b), an output is generated from the comparator 2 to fall the FF3, so that no output is generated from the AND circuit 4. Consequently, the iPL signal is not outputted and the infinite loop an be prevented. |
