| 摘要 |
A number of moving objects and stationary playfield objects are generated on a video display screen by sharing memory and circuitry on both a physical and time-share basis. Video graphics data for playfield and motion objects is stored in a read-only memory (ROM). An object attribute memory, which may be updated at any time, is scanned during each horizontal retrace interval to provide information used to selectively read moving object video data from the ROM and assemble and store a complete horizontal line of moving object video graphics data in a separate staging memory. During active scan time of the horizontal video display line, the assembled line of moving object video data is accessed from the staging memory and communicated to the display screen via appropriate video circuitry to produce the video of the moving objects. At the same time, the object attribute memory is accessed for playfield object information which, in turn, is used to address the video graphics ROM to produce the actual video image of playfield objects. The video image of playfield objects so obtained is also communicated to the display screen through the video circuits. |
