OpenTendo Recreates the Original Nintendo NES Motherboard
This faithful recreation of the original NES motherboard requires the original CPU, PPU, and lockout chip to function.
The original Nintendo Entertainment System (NES) debuted in 1986 (in the U.S.), and although now 34 years old, it’s still a popular gaming console for gamers and retro enthusiasts. Like any old technology, replacement hardware gets tougher to find as the years go by. That said, Nintendo fans such as "Redherring32" are determined to keep that gaming console alive by back-engineering the needed hardware, in his case, a recreation of the NES motherboard.
Redherring32’s designed the open source OpenTendo front-loading NES motherboard as close to the original as possible but made a few improvements, such as enabled expansion audio. Redherring32 explains, “The design is as true to the original board as possible, with subtle changes where needed to compensate for outdated/unsourcable parts, as well as some improvements. Since this project is open-source, you may do as you like with it, whether that is to make boards for personal use, sell replacement NES boards, or to use the provided info for further custom PCB work/designs.”
The OpenTendo is outfitted with both old and new hardware, which features most of the necessary ICs, headers, and pins, but it isn’t a direct replacement for the original. In fact, Redherring32 states that getting the board operational requires the original CPU and PPU, but they can be swapped for aftermarket versions, but will affect audio and are not compatible with all games. Technically, the original lockout chip is required as well, but users can drop-in a NullCIC as a replacement if needed.
Redherring32 has uploaded his OpenTendo on GitHub, which includes all the necessary files, schematics, and footprints for those who would like to recreate the board.