| 摘要 |
PURPOSE:To attain a simple data transfer system by setting a transmission or reception start pointer an address register and providing a control means to a transfer control means to indicate the transfer direction to switch the transmission and reception pointers of a pair of buffers. CONSTITUTION:An IO controller 16 stores a transmission start pointer Ps in an address register 14 so set a reception enable state. When a receiving interruption signal 52 is received from a communication interface part 3, a direct memory access controller 13 transmits the read signal to a register 3a of the part 3 and the write signal to a buffer 12 respectively. Then the controller 13 opens the gate of an address counter 15 to deliver the reception start pointer Pr of the buffer 12 through a local bus 100 and sends the reception data to the buffer 12. The controller 16 reads the reception data covering the pointer Pr through the pointer Ps of the counter 15 after the reception is over and transfers these data to a main memory 5.
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