The concept of video priorities is easy to understand if you imagine that four fingers of one of your hands represent the four pairs of sprites and two fingers of your other hand represent the two playfields. Just as you cannot change the sequence of the four fingers on the one hand, neither can you change the relative priority of the sprites. However, just as you can intertwine the two fingers of one hand in many different ways relative to the four fingers of the other hand, so can you position the playfields in front of or behind the sprites. This is illustrated in Figure 7-2. Figure 7-2: Analogy for Video Priority Five possible positions can be chosen for each of the two "playfield fingers." For example, you can place playfield 1 on top of sprites 0 and 1 (0), between sprites 0 and 1 and sprites 2 and 3 (1), between sprites 2 and 3 and sprites 4 and 5 (2), between sprites 4 and 5 and sprites 6 and 7 (3), or beneath sprites 6 and 7 (4). You have the same possibilities for playfield 2. The numbers 0 through 4 shown in parentheses in the preceding paragraph are the actual values you use to select the playfield priority positions. See next section Setting the Priority Control Register . You can also control the priority of playfield 2 relative to playfield 1. This gives you additional choices for the way you can design the screen priorities .
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