Atari 7800:Controller Adapters

In developing the Atari 7800, Atari and General Computer set out to correct a number of flaws with the system's immediate predecessor, the 5200. One of these flaws was the 5200's controller, which was fairly complex, did not have a self-centering joystick and had significant reliability issues. Instead, Atari introduced the CX24 Pro-Line joystick alongside the 7800, which used a digital joystick and just two buttons, one on each side. Whether or not it was a major improvement over the 5200 controller is up for debate, as the Pro-Line stick has become notorious for its poor ergonomics and arguably dubious reliability.

Upon the 7800's release in PAL regions in 1989, Atari also introduced an NES-style gamepad known as the "Multi System Joypad Controller" and bundled two of them with the console. This gamepad also featured a removable thumbstick, much like earlier versions of the Sega Master System gamepad. This controller is also known by its model number, CX78. Although Atari apparently planned to release this controller in North America (even depicting it in "The Atari Advantage" posters that came included with some games), they never did so and so it only saw release in PAL territories. As a result, it has become somewhat sought after by Atari enthusiasts. While this controller is widely considered to be superior to the Pro-Line stick, it still has several faults, such as an imprecise D-pad, fire buttons that are spaced too far apart, and a thin cable which can develop internal breaks.

Although the 7800 can use almost any 2600-compatible controller, a significant number of games require having both buttons. Due to the 7800's unique controller pinout, other 9-pin controllers that feature more than a single button are not compatible with these games. Fortunately, a number of people have developed adapters to use controllers from other consoles on the 7800, many of which can be easily assembled with basic soldering knowledge.

GC7800
Developed by SWiT, this adapter allows for Sega Genesis/Mega Drive controllers to be used on the 7800, with B and C acting as the left and right fire buttons respectively. It can be assembled in-line with a 9-pin controller extension cable cut in half, or with DB9 ports soldered on so that it can be attached directly to the 7800. It is also compatible with wireless Genesis controllers and Master System pads. All of the parts required are very easy to source and so this adapter is highly recommended.

NES Controller Conversion
With some work, an NES controller can be converted for use with the 7800 as well as for other systems which use Atari-compatible controllers. This can be accomplished by desoldering the original cable along with the 4021 multiplexer chip, and then wiring up the controller PCB appropriately.

Best Electronics CX78 Upgrade Kit
In recent years, long-time Atari merchant Best Electronics set out to correct all of the flaws with the CX78 pad and released an extensive upgrade kit in 2019. The kit includes newly designed PCBs, more tactile membranes with gold-plated contacts and a thicker cable with a proper strain relief. It is a mostly drop-in kit, with some shell modification required to accommodate the thicker cable. Although it obviously does not correct some of the CX78's ergonomics, it does turn it into a much more durable and reliable controller.