Atari XL

Advanced Graphics
167
memory. At the start of the list, ANTIC is told that
display memory is at 112 + 62*256 = 15984 (for a
16k machine), and this is where data for the mode 2
display is stored. After completing the 10 mode 2
display blocks, ANTIC is directed elsewhere in
memory, to 96 + 63*256 = 16224 (for a 16k
machine), where it finds the data for the mode 0
display.
You can apply the same principle to creating your
own mixed mode displays.
As an example, the following program alters the
display list of a mode 0 screen to cause any data
appearing on the lower half of the screen to appear
in multicolour character mode (mode 12).
10 GRAPHICS 0
15 SETCOLOR2,3,14:SETCOLOR4,3,14
20 DL=PEEK(560)+256*PEEK(561)
30 FOR Z=18 TO 29
40 POKE DL+Z,4:NEXT Z
Line 10 sets up the mode 0 display list and the
contents of colour registers 2 and 4 are set equal so
that the background of both displays appears the
same.
If you run the program, it will turn the entire
screen pink. If you now list the program all will
seem normal until you list it again - the second
listing on the lower half of the screen will be in .
mode 12!
This is a fairly straightforward and not
particularly useful demonstration of mixed mode
displays. A better but more complex one is to
create a mode 8 graphics display, and label it in a
combination of text modes. The following program