| 摘要 |
Text is displayed on a VDU (23) using a character generator (26) and a generator (27) for attributes such as underline, enhanced brightness and so on. The codes for the generators are stored in a page store (29). Two auxiliary memories (35 and 36) are used to store address pointers. These memories are used in alternate raster scans to control the display, the unused memory being updated for the next raster scan. Each address pointer comprises an entry for every VDU scanning line and determines which dot video line signal will be used in that scanning line by specifying the data row address in the page memory (29) and the dot matrix row number to be used by the generators (26 and 27). Such address pointers enable complete control over the display for the purpose of defining windows, scrolling the display smoothly and slowly at the rate of one scanning line per frame and smooth expansion of a strip on the display by dulplication of lines. A CPU 10 effects the control by determining the address pointers written into the auxiliary memories. For graphics display, the address pointers store for each scanning line the number of the bit line to be used in creating the image.
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