Brains!

The Atari 2600 boasts:

1.19MHz 8-bit processor

128 bytes RAM

192 x 160 pixel resolution

128 colors, with max 4 colors per line

2 channel mono sound

Unlike most earlier consoles -- where the games were stored on internal chips -- the Atari 2600 stored games in Read Only Memory (ROM) chips housed in external cartridges. This allowed for a potentially infinite number of playable games for the console.