摘要 |
In a buffer memory are stored messages given to a specific task in order of arrival. Messages of same types may be stored in the buffer memory. In a different order from the order of arrival, a processing section performs task processing on the basis of the messages stored in the buffer memory. If two messages of a same type are present in the buffer memory, one of the messages which has arrived later than the other is processed with priority irrespective of the order of arrival, and the other message which has arrived earlier is deleted from the buffer memory. If there is present in the buffer memory such a message instructing transfer of parameters corresponding to a function that is not currently assigned, this message itself is deleted from the buffer memory as being ineffective, so as to process a next message.
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