| 摘要 |
PURPOSE:To prevent a fault which is caused by a long-time holding state of a microprocessor, by releasing the microprocessor holding state with the time-up of a timer. CONSTITUTION:The microprocessor 61 gives the use request signal of the main memory 2 to the line 68, and this request signal sets the FF69 and also starts the time counting of the timer 67. With setting of the FF69, the processor 61 put under the holding state with the FF71 set. In this case, the holding state of the processor 61 is kept as it is if the request signal having a higher priority then the own request signal. In such case, the timer 67 counts the prescribed time to have a time-up and then supplies the interruption siganl to the processsor 61 as well as set the FF69. As a result, the holding state of the processor 61 is released, and at the same time the FF71 is reset. Accordingly the processor 61 is never kept under the holding state for a certain time longer than the prescribed time which is counted by the timer 67. |
