| 摘要 |
<p>Video display control apparatus for a visual display device 11 employing a television-type raster in a word processor has a display memory 13, a column counter 25 and a row counter 28 adapted to address the display memory 13. Each location of the display memory 13 has a address comprising a column number and a row number. A clock oscillator 18 and a timing chain 19 produce raster timing signals and column and row timing signals. The count in the column counter 25 tracks the line being scanned, and the count in the row counter tracks successive groups of lines in the raster. The display data output of the display memory 13 control a character matrix memory 15 acting through a parallel-to-serial converter 16 to cause alphanumeric characters to be displayed in rows by the display device. So that the information display by the device 11 can be varied in a convenient manner, the row counter 28 is coupled to the display memory 13 through a random access memory 30 which stores information from a central processor unit 14. This stored information determines which set of sequential row addresses shall be supplied to the display memory 13 as the row counter 28 carries out its counting sequence, and includes an instruction associated with a selected row address which causes a reset signal to be supplied to the column counter 25 so that for this row the characters displayed start at the character stored in the first column of locations in the display memory 13, the column addresses generated by the column counter 25 being otherwise selectable as any set formed by a predetermined number of consequetive column addresses for alphanumeric character locations in the display memory 13.</p> |
