Programming Atari's custom chips
De Re Atari explains graphics, sound and operating system techniques using 400/800 examples. It assumes knowledge of Atari BASIC and basic 6502 assembly language. Using the code on XL/XE requires accounting for operating system and memory changes.
ANTIC, Player/Missile and the operating system
Chapters 2–6 cover ANTIC display lists, colour registers and character sets, Player/Missile graphics, DLI interrupts and scrolling. They show how to combine graphics modes, animate objects and change the appearance of successive screen regions.
Chapter 7 covers sound, chapter 8 the operating system, chapter 9 DOS and chapter 10 Atari BASIC. Later sections discuss cassette recording, television artefacts, GTIA modes and memory management.