The Atari 2600 is a home video game console released in September 1977 by Atari, Inc. It is credited with popularizing the use of microprocessor-based hardware and ROM cartridges containing game code. This format contrasts with the older model of having non-microprocessor dedicated hardware, which could play only the few games which are physically built in to the unit. The console was originally sold as the Atari VCS, for Video Computer System. Following the 1982 release of the Atari 5200, the VCS was renamed "Atari 2600", after the unit's Atari part number, CX2600.