| 摘要 |
The system takes advantage of the GDC and employs a maximum of four starting addresses and four region length values to provide the addresses for the split screen scrolling operation. At this time the region length value provides the impetus for 'advancing circuitry' to scan the next adjacent line, in the off screen region of memory, and the information in that adjacent line becomes the new information which is added to the bottom line of the scrollage region on the display. The system provides a starting address and a region length value for each fixed region as well as two starting addresses and two region length values for scrolling regions. The system is arranged to have an off screen region which lies adjacent to a scrollable region of memory.
|
