| 摘要 |
PURPOSE:To speed up overwriting processing by controlling a CAS signal and inputting pattern data to be overwritten to a frame buffer composed of a dynamic RAM directly, and then overwriting the data. CONSTITUTION:The CAS signal is controlled to input the pattern data to be overwritten in the frame buffer 4 directly, and the data is overwritten. Namely, when the pattern data to be overwritten is black '1', '0' is inputted to a CAS input terminal and when white '0', '1' is inputted to the CAS input terminal. When said pattern data is black '1', the CAS signal inputted to the CAS input terminal becomes active and '1' data is inputted from data input terminals of DRAMs 4-1-4-4 by a pull-up resistance 10 connected to a data input terminal and overwriting is carried out speedily. When said pattern data is white '0', the CAS signal inputted to the CAS input terminal becomes nonactive and the DRAMs enters RAS only refreshing operation, so that the data is not overwritten. |
