The Atari 800 was the bigger brother of the Atari 400, with a full-travel keyboard, two cartridge slots under a lift-up lid and room for memory cards inside. It was designed by the team behind the Atari 2600 and was one of the most capable home computers of its time.
Its custom chips did work other machines left to the processor. ANTIC was a small display processor with its own program, the display list, which set the graphics mode line by line.
A palette of 128 colours. A normal screen showed about nine at once: five for the background and four for the sprites, which Atari called players and missiles. Programmers changed colours partway down the screen to show far more, and could mix text and graphics modes on one screen.
POKEY gave four channels of square waves, which could be distorted with noise into engines, wind and explosions. Pairs of channels could join for finer pitch.