| 摘要 |
PURPOSE:To recognize accurately the position where a pattern is to be drawn, by detecting the point where the fed X and Y coordinates coincide with the scan address of a CRT. CONSTITUTION:The continuous pushes of a CTRL key and an alphabetic D key are informed to a CPU1, and therefore the CPU1 delivers the coordinate input requests in X and Y directions, i.e., optional dot positions of the CPU1 to a key part 2. An operator feeds both X and Y axis coordinates 123 and 60, and these X and Y coordinate addresses are latched to X and Y coordinate latching memories 13 and 14 respectively through an X/Y direction address bus 20 to be stored in a buffer memory 15. While a scan address 18 is supplied from a CRT controller 3, and this signal and the output of the memory 15 are delivered through a coincidence circuit 16. Then this signal and the output of a CRT display data memory 8, i.e., an ordinary video signal are supplied to an OR gate 11 and then displayed on a CRT4. |
