o Vertical resolution, or interlacing.
o Data fetch and modulo, which tell the system how much data to put on a horizontal line
and how to fetch data from memory to the screen.
In addition, you need to allocate memory to store the playfield, set pointers to tell the
system where to find the data in memory, and (optionally) write a Copper routine to
handle redisplay of the playfield.
HEIGHT AND WIDTH OF THE PLAYFIELD
To create playfield that is the same size as the screen, you can use a width of either 320
pixels or 640 pixels, depending upon the resolution you choose. The height is either 200
or 400 lines for NTSC, 256 or 512 lines for PAL, depending upon whether or not you
choose interlaced mode.
BIT-PLANES AND COLOR
You define playfield color by:
1. Deciding how many colors you need and how you want to color each pixel.
2. Loading the colors into the color registers.
3. Allocating memory for the number of bit-planes you need and setting a pointer to each
bit-plane.
4. Writing instructions to place a value in each bit in the bit-planes to give you the correct
color.
Table 3-1 shows how many bit-planes to use for the color selection you need.
Number of Number of
Colors Bit-Planes
1- 2 1
3- 4 2
5- 8 3
9-16 4
17-32 5
Table 3-1: Colors in a single playfield.
- Playfield Hardware 39 -
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