AI Summary: Open ‘Tendo is an open-source hardware project that recreates the original 1985 Front-Loading NES motherboard, focusing on documentation and preservation through reverse engineering. The repository provides comprehensive design files, including a bill of materials, schematics, and PCB layouts in KiCad format, while intentionally excluding modern video output improvements like RGB or HDMI. Users are encouraged to utilize the designs for personal projects, manufacturing replacement boards, or for further custom PCB work.

README

Open ‘Tendo

An Open-Source HardWare (OSHW) recreation of the original 1985 Front-Loading NES motherboard.

Note on RGB and HDMI

Neither RGB nor HDMI video output were or are a goal of the OpenTendo project, the goal was/is documentation and preservation, and the project was an exercise in reverse engineering. As such “improved” video outputs will not be added to OpenTendo.

NESRGB and Hi-Def NES can be installed as normal, but will not be incorporated into the OpenTendo PCB

Repository Structure

Branches

File Structure

.
├── BOM              # Contains the bill of materials.
├── Board Files      # Contains all files necessary to open the project in KiCad.
|   └── Libraries    # Contains a library of all of the custom footprints used on the board.
├── Scans            # Contains the scans of the OEM NES board.
└── Schematics       # Contains schematics for the OEM frontloading NES board revisions,
                       some schematics represent more than one revision

The gerber files required to order PCBs can be found under releases.

Recommended PCB specs

• 2 layers

• 119mmx196mm

• 1.6mm thickness

• HASL or ENiG surface finish

• And any color you want!

[!IMPORTANT] OpenTendo have some solder mask overlapping the edge connector to secure the pads and the thin traces. Some fabricators might see this as an error and might try to fix it.

We recommend leaving a note saying that the solder mask overlap on the edge connector is intentional and NOT an error when ordering the PCB.

The design is as true to the original board as possible, with subtle changes where needed to compensate for outdated/unsourcable parts, as well as some improvements. (Expansion audio enabled, and other minor changes)

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.

I am not in any way affiliated with Nintendo, I’m just doing this in my free time as a stepping stone into further Reverse Engineering work.

[!NOTE] Please check the BOM for the list of components needed from the OEM NES

License

Licensed under the TAPR Open Hardware License (www.tapr.org/OHL)

©Redherring32 2019-2024

Credits

=Lockster= - Helping me tremendously along the way, keeping me from going insane, and cleaning up/helping with the final schematic.

Krzysiobal - Putting together the NES-CPU-11 schematic that my schematic is largely referrenced against.

Muramasa - Ported to KiCad v8, PCB clean up, and fixing the EXP port footprint.

Kamoteshake - Schematic clean up and fixing the EXP port footprint.

And to all of the awesome people in the NES scene, I wouldn’t have been able to do this without the awesome work that some very clever people did before I got here.