| 摘要 |
PURPOSE:To prevent pseudo interruption due to noise, by allowing a central processing unit to receive the interruption, only when a timing signal coincides with an interruption signal produced for a constant period. CONSTITUTION:Signal lines l1, l2 and l3, l4 are coupled via a central processing unit CPU having functions to receive interruption signals and external devices I/O which produce the interruption signals through an interface buffer VIA which executes the interrupting function. The CPU and the VIA are connected via an AND gate G at interrupting signal lines IRQ, IRQ' via the AND gate G, and pulses with a specified period from a timing signal generating circuit TMG is inputted to other inputs of the gate G. The interrupting signal from the VIA is transmitted to an interrupting signal line IRQ, and the gate G transmits an output to the CPU, only when the signal coincides with the pulse from the TMG. Thus, the production of an artificial interrupting signal due to noise as shown by F, G in Figures is prevented to prevent a malfunction for the entire system. |
