o How system direct memory access (DMA) is controlled
o How interrupts are controlled and sensed
o How reset and early powerup are controlled
VIDEO PRIORITIES
You can control the priorities of various objects on the screen to give the illusion of three
dimensions. The section below shows how playfield priority may be changed relative to
sprites.
FIXED SPRITE PRIORITIES
You cannot change the relative priorities of the sprites. They will always appear on the
screen with the lower-numbered sprites appearing in front of (having higher screen
priority than) the higher-numbered sprites. This is shown in Figure 7-1. Each box
represents the image of the sprite number shown in that box.
___
__| 7|
__| 6|__|
__| 5|__|
__| 4|__|
__| 3|__|
__| 2|__|
__| 1|__|
| 0|__|
|___|
Figure 7-1: Inter-Sprite Fixed Priorities
- 202 System Control Hardware -
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