Now you're developing with power.
The open-source FPGA development cartridge for the Nintendo Entertainment System.
Design custom mappers. Debug on real hardware. Ship your game.
┌─────────────────────┐
│ ┌───────────────┐ │
│ │ NES-DEV-CART │ │
│ │ v4.0 │ │
│ │ ┌───────┐ │ │
│ │ │ FPGA │ │ │
│ │ │ 25K │ │ │
│ │ └───────┘ │ │
│ │ [USB-C] [LED]│ │
│ └───────────────┘ │
│ │
│ ████████████ │
└──┤ ├──────┘
│ ░░░░░░░░░░ │
└────────────┘
NES-DEV-CART is a professional development cartridge that plugs directly into your NES console. It replaces the ROM chip with a modern FPGA, giving you complete control over every signal on the cartridge bus.
No more burning EPROMs. No more swapping chips. Just plug in a USB-C cable, upload your code, and watch it run on real hardware. The onboard UART gives you a live debug console while your game runs.
Whether you're building your first homebrew game or designing a custom mapper chip that never existed, NES-DEV-CART gives you the tools the original developers never had.
Gowin GW5A FPGA with enough logic to implement any NES mapper ever made — and invent new ones that weren't possible in 1985.
FT2232HL dual-channel interface. Channel A: JTAG for FPGA programming. Channel B: UART debug console. No external programmer needed.
4x 74ALVC164245 level shifters give your FPGA bidirectional access to all 50+ NES bus signals. CPU, PPU, CIC — everything.
UART output streams to your terminal in real time while your game runs. printf-debug your NES code like it's 2026.
Tang Primer 25K plugs in via DF40 connectors. Swap, upgrade, or reprogram the FPGA module without soldering.
Full KiCad source files, auto-generated from Python scripts. Fork it. Modify it. Make it yours. MIT licensed.
Every signal from the 72-pin cartridge connector, level-shifted and routed to your FPGA.
15 address lines, 8 data lines, read/write control, ROM select, and clock. Full CPU-side cartridge interface.
14 address lines, 8 data lines, read/write strobes, and CIRAM control. Direct CHR-ROM and nametable access.
Interrupt request, 21.48 MHz system clock, CIC lockout bypass, and 10 expansion port lines for advanced mapper features.
Develop and test NES games on real hardware during development. See exactly how your code behaves on actual silicon — not an emulator's approximation. USB-C UART gives you live debug output while your game runs.
Design mapper chips that never existed. Implement MMC1, MMC3, VRC6, or invent entirely new banking schemes with 25K logic cells. The original developers were limited to what Ricoh would fabricate — you're not.
Build expansion audio hardware like the VRC6 or Sunsoft 5B sound chips. Mix additional audio channels into the NES output using the expansion port lines. Create sounds the stock APU can't produce.
Capture and analyze NES bus traffic in real time. Reverse-engineer cartridge protocols. Study how original mapper chips worked by observing the actual electrical signals on a running console.
Build your own EverDrive-style flash cartridge with custom features. Load ROMs from SD card, implement save states, add in-game menus. The FPGA has enough logic for a complete flash cart system.
Learn FPGA development with a tangible, fun project. Understand how retro hardware works at the gate level. Teach digital design using a platform students actually want to use.
| Module | Sipeed Tang Primer 25K |
| FPGA | Gowin GW5A-LV25MG121 |
| Logic Cells | 25,344 LUTs |
| Block RAM | 864 Kb |
| Max Clock | 125 MHz |
| Connection | 2x DF40C-60DS (0.4mm pitch) |
| Controller | FTDI FT2232HL |
| Channel A | JTAG (TCK/TMS/TDI/TDO) |
| Channel B | UART (TX/RX) |
| Speed | USB 2.0 High Speed (480 Mbps) |
| Connector | USB Type-C |
| Power | Bus-powered or NES-powered |
| IC | 4x 74ALVC164245DGG |
| Direction | Bidirectional (5V ↔ 3.3V) |
| Channels | 32 total (8 per IC) |
| Speed | <3ns propagation delay |
| Bus Width | 50+ NES signals |
| Dimensions | 100mm × 110mm (L-shaped) |
| Layers | 4 (signal/GND/power/signal) |
| Thickness | 1.6mm |
| Finish | ENIG + gold fingers |
| Edge Connector | 72-pin, 30° bevel |
| Components | 36 SMT + 2 THT |
| NES-DEV-CART | EverDrive N8 Pro | EPROM Cart | |
|---|---|---|---|
| Price | $99–$129 | $179 | ~$30 |
| Custom Mapper Logic | 25K LUT FPGA | Fixed (Cyclone IV) | None |
| USB Programming | USB-C JTAG + UART | SD Card only | EPROM burner |
| Debug Console | Real-time UART | No | No |
| Open Source | Full hardware + HDL | No | N/A |
| CIC Signals | Full access | Built-in CIC | None |
| Expansion Port | 10 lines + GPIO header | Limited | None |
| Standalone Mode | USB-powered | NES only | NES only |
NES-DEV-CART v4 fully assembled PCB with all SMT components soldered and tested
2x5 JTAG and expansion GPIO pin headers pre-soldered
Quick-start guide with pinout reference and mapper templates
Full KiCad source files, BOM, and example HDL projects
USB-C cable, NES console, and Tang Primer 25K module not included. Tang Primer 25K ($25.99) required and available from Sipeed. Complete Kit includes the module.
Yes. The NES-DEV-CART is the carrier board — the Tang Primer 25K provides the FPGA that runs your logic. It plugs into the board via two 60-pin DF40 connectors. The Complete Kit ($129) includes it. The Assembled Board ($99) and Bare PCB ($19) do not — order one from Sipeed for $25.99.
The NES-DEV-CART is designed for the NES front-loader (NES-001) with 72-pin connector. The top-loader uses the same 72-pin connector and should be compatible, though the L-shaped PCB profile is optimized for front-loader clearances.
You'll need the Gowin FPGA IDE (free) or open-source Yosys/nextpnr toolchain to write and synthesize your HDL. For uploading via USB, OpenOCD or the Gowin programmer connects through the FT2232HL JTAG interface. Any terminal emulator (minicom, PuTTY, screen) works for the UART debug console.
Yes. The USB-C port provides power through a Schottky OR circuit, so the FPGA runs standalone. You can develop and test your mapper logic on the bench, then plug into the NES for real hardware verification.
Not directly — the Famicom uses a 60-pin connector vs. the NES 72-pin. A Famicom variant is possible with the same FPGA module and level shifters on a different PCB. The design is open source, so community adaptations are welcome.
An EverDrive is a consumer flash cartridge for playing ROMs. NES-DEV-CART is a development tool for building hardware. You get raw FPGA access to implement any mapper logic, plus USB debugging. Think of it as the difference between using a game console and building one.