This chapter discusses how to hack Atari 2600 and 7800. Atari introduced the Video Computer System (VCS) in 1977. The VCS, later renamed the 2600, was part of the first generation of videogame systems that weren't hardwired to play a certain set of games. Instead, they could be reprogrammed time and time again by the user, who purchased new game cartridges. The Atari 2600 is one of the most successful game consoles of all time with a place in history as the machine that started the home videogame craze. Under pressure from competitors that were eroding Atari's market share by producing competing consoles as well as clones of the 2600, Atari hastily released the Atari 5200 SuperSystem in 1982. The Atari 5200 was a repackaged Atari 400 computer and did not represent development of a new game system from scratch. That would not happen until the introduction of the Atari 7800 five years later. The Atari 7800 is more closely related to the 2600 than it is to the 5200. The Atari 7800 is backward compatible with 2600 games—the only system Atari would ever produce with built-in backward compatibility. The cartridges for the two systems are of the same size, with the only discernible difference being two additional “fingers” on the cartridge connector for 7800 games. Both systems feature 9-pin controller ports, and 2600-compatible controllers work fine with the 7800. 2600 controllers can be used with 7800 games except for those that require two independent fire buttons. The 7800 also uses the same hardware as the 2600 to produce sound, which unfortunately hinders the 7800 in the audio department.