From its release in 1977 until 1983, the Atari 2600 was officially called the Video Computer System, in response to Fairchild Semiconductor's Video Entertainment System. The console was later renamed after its model number, CX2600.
Instead of following the trend of building a limited number of games into the system like the Magnavox Odyssey 100, the Atari 2600 used removable cartridges to store games like Space invaders, Pac-Man and Pitfall!
Each player could select the difficulty of the game they were playing by simply flipping a switch from "A" to "B". Which one was harder is anyone's guess.