HOW TO INTERPRET THE COLLISION DATA
The collision data register, CLXDAT, is read-only, and its contents are automatically
cleared to 0 after it is read. Its bits are as shown in Table 7-3.
Table 7-3: CLXDAT Bits
Bit
Number Collisions Registered
15 not used
14 Sprite 4 (or 5) to sprite 6 (or 7)
13 Sprite 2 (or 3) to sprite 6 (or 7)
12 Sprite 2 (or 3) to sprite 4 (or 5)
11 Sprite 0 (or 1) to sprite 6 (or 7)
10 Sprite 0 (or 1) to sprite 4 (or 5)
9 Sprite 0 (or 1) to sprite 2 (or 3)
8 Even bit-planes to sprite 6 (or 7)
7 Even bit-planes to sprite 4 (or 5)
6 Even bit-planes to sprite 2 (or 3)
5 Even bit-planes to sprite 0 (or l)
4 Odd bit-planes to sprite 6 (or 7)
3 Odd bit-planes to sprite 4 (or 5)
2 Odd bit-planes to sprite 2 (or 3)
1 Odd bit-planes to sprite 0 (or 1)
0 Even bit-planes to odd bit-planes
NOTE
The numbers in parentheses in Table 7-3 refer to collisions that will register only if you
want them to show up. The collision control register described below lets you either ignore
or include the odd-numbered sprites in the collision detection.
Notice that in this Table, collision detection does not change when you select either single
or dual playfield mode. Collision detection depends only on the actual bits present in the
odd-numbered or even-numbered bitplanes. The collision control register specifies how to
handle the bitplanes during collision detect.
- 208 System Control Hardware -
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