Page "Atari 7800" Paragraph 43

Despite having the capability to support sound chips in cartridges, almost no 7800 cartridges feature POKEY hardware for enhanced sound.

Ballblazer, released in 1987, uses the POKEY to generate all music and sound effects.

Similarly, Commando, released in 1989, uses a POKEY to generate in-game music while the TIA generates the game's sound effects for a total of 6 channels of sound.