| 摘要 |
PURPOSE:To shorten a reception interruption processing time by executing the reception data transmission between a connection part and a communication processing part by means of DMA transmission in which reception character and reception status are transmitted every reception character, and providing, in the communication processing part, DMA wire byte counter groups corresponding to DMA request from respective line connection parts. CONSTITUTION:A microprogram sets its start memory address in a DMA write address counter 25 corresponding to the line connection part 3, and sets its number of bytes in the DMA write byte counter 26. After storing said address and the byte number by itself, the microprogram permits the operation of a reception control circuit 41. A serial reception data signals 401 from a communication line are inputted to a reception register 42, and reformed into parallel reception characters. And these reception characters are moved to a reception buffer register 43. At this time, these characters are subjected to various kinds of error checks and the check of the presence/absence of start-stop synchronization errors in the case of start-stop system and a resulting information also are moved from the reception control circuit 41 to a reception status register 44.
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