| 摘要 |
PURPOSE:To make partial correction of data in a scan ring by one scanning operation by providing a change-over control circuit that switches data inputted to a mask buffer and the scan ring depending on output of the mask buffer. CONSTITUTION:Mask data that make places corresponding to 7 stages of shift register latch that require change '1' and make places corresponding to stages that do not require change '0' are prepared in a mask buffer 8. Then, data to be inputted to shift register latch stages that require change and dummy data corresponding to stages that do not require change are arranged in specified order and prepared in a scan buffer 3. When scan in operation is made, if output from a #2 shift register 9 is '0' output data from a scan ring 6 are returned to the inputting section of the scan ring 6 without any change, and if output is '1', data in a #1 shift register 4 are selected as input data to the scan ring 6. Thus, places that require change are replaced by necessary data. |
