| 摘要 |
PURPOSE:To obtain an inexpensive video data sampling circuit of a low speed by extracting the video data by (m) bits in a single horizontal scan period and transferring the video data to a memory. CONSTITUTION:A counter 10 fetches the sampling address of a register 9 for a blanking period of the horizontal synchronizing signal supplied from a terminal B and counts (m) bits by the video clock supplied from a terminal A to transmit a carry signal to an S/P converting circuit 11. The circuit 11 always converts the video data given from a terminal C into parallel signals to send them to a latch circuit 12 and gives an instruction for transmission of the parallel signals equivalent to (m) bits by the carry signal received from the counter 10. A direct memory access DMA request circuit sends a DMA request to a DMA control circuit 14 by the carry signal of the counter 10. While the circuit 14 stores (m) bits receives from the circuit 12 into a memory 6. A processor 1 reads successively the data equivalent to (m) bits out of the memory 6 and sends them to a dot printer 16 for print. |
