The Atari 5200 was released in 1982 and featured four controller slots in comparison to the other systems of the day which only had two. It also featured a revolutionary analog joystick controller, numeric keypad, two fire buttons on both sides, start, pause, and reset.
However by the 1983 revision, the 5200 had only two ports. The updated r/f switch and power supply, were changed as well. The 5200 was made to compete with the Intellivision, but it ended up competing with the Colecovision, soon after its release. It had a number of design flaws that messed up the usability of the system, and is generally considered to have performed poorly on the market. The 5200 was also based strongly on Atari inc's existing 400/800 computers of the time, and had almost identical hardware, however the two systems were not compatible, due to a number of issues.
The Atari 5200's software incompatibility with the 2600 caused the system to suffer on the market. In 1983 an adapter was released that allowed the playing of 2600 games on the 5200, but another problem was the lack of attention Atari inc gave to the new console, It also faced an uphill battle in trying to compete with Colicovision's head start in the market, as well as the fact that they had exhausted their resources on the 2600 a few years earlier.