| 摘要 |
PURPOSE:To facilitate the easy switching of the DMA transfer of received data, by installing a memory which stores plural pairs of codes showing both the start and stop codes of the received data to a circuit controller containing an ordinary DMA control circuit. CONSTITUTION:A code memory 23 which stores plural codes corresponding to the start and stop codes plus a comparator 24 which reads the start and stop codes out of the memory 23 and compares them with a received data are installed at a circuit control part 1 of a device containing an ordinary DMA control circuit. The received data is transferred directly to a main memory with no intervention of a CPU and in accordance with a coincident output obtained from the received data of the comparator 24 and the start code read out of the memory 23. At the same time, the stop code read out of the memory 23 is transferred to the main memory of the received data in accordance with the coincident output to the received data. In such way, the demarcation can be facilitated for the DMA transfer of the received data. |
