| 摘要 |
PURPOSE:To reduce the software load to shorten the processing time and at the same time to improve the overall efficiency of a system by allotting a portion of work of the data writing operation involved by a shift action to the hardware as much as possible. CONSTITUTION:The mask data which indicates the shift amount of the input data is previously set to a mask register incorporated into an I/O controller 13. For a shift action with no intervention of a CRT controller 9, the input data for writing is shifted by a fixed amount within a data controller 15 in accordance with the contents of the mask register set previously. Then the gate conditions corresponding to the contents of the mask register are given to the shifted data as well as to the read data read out of a screen memory 22. Thus the new synthetic data is obtained and written to the memory 22. As a result, a shift write action can be done with an instruction of just one time. This shortens the processing time and at the same time improves the overall efficiency of this system.
|
