APPENDIX ELEVEN



59280,81       E790,91        ?
     Seems to be the same DLI vector address as 512-513.

GTIA Graphics Modes

Graphics modes 9, 10, and 11 are unique to the GTIA chip; the early
CTIA chip didn't have them. Of course, the GTIA is standard now in
all later model 400, 800, XL, and XE models. The GTIA modes all use
8138 bytes of RAM, have 80 X 192 full-screen (no text window)
resolution, and have no border color. Each pixel is a wide, but short,
rectangle with a ratio of 4:1 for width to height. Each pixel uses four
bits. Here's a small chart which summarizes these modes.

GR#  Colors     SETCOLOR Registers
9    1 (16 lum)     4      712     Use the COLOR com-
                                   mand (0-15) for
                                   luminance

10         9        0      704     Must be POKEd
                    1      705     Must be POKEd
                    2      706     Must be POKEd
                    3      707     Must be POKEd
                    4      708     Use COLOR 0
                    5      709     COLOR 1
                    6      710     COLOR 2
                    7      711     COLOR 3
                    8      712     COLOR 4(BAK)

11   1 (16 hues)    4      712     Use COLOR command
                                   (0-15) for hue

Information on GTIA modes has been published in many books and
magazines, including De Re Atari and Your Atari Computer by Poole
et al. (a revised edition of the latter is available now). An example of
adding a text window to a GTIA screen by way of a DLI was in
David Sander's article in Antic, April 1983.