The Atari Trak-Ball (CX80)

This is Atari's "Trak-Ball" controller (CX80). It wasn't meant to be used on the 2600 only. It could be used on the computers and on the 7800 as well. Atari released two versions: The CX22 (before the CX80), which was intended as peripheral for the 2600. It had the "2600" on its case and had round fire-buttons.