o Horizontal resolution.
o Vertical resolution, or interlacing.
(
o
Data
fetch and modulo, which tell the system how much
data
to
put
on a hor-
izontalline 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 a 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 lines or 400 lines, 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.
34
Playfield Hardware
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