OpenTendo – NES Replacement Board (Front Loader)


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OpenTendo – NES Replacement Board

The OpenTendo is an open source board replacement for the Front Loading NES system. This listing is for release V1.2 of ONES-CPU-01.

This PCB is 1.6mm thick with an ENIG finish.


Please be sure to see the release notes here. The Bill of Materials (BOM) can be found here.

Outside of the Bill of Materials a few parts can’t be purchased new. The below parts can be purchased from places like Aliexpress, Ebay, or UTSource.

  • U5 PPU RP2C02 (harvested from original Famicom/NES or UA6528 (clone)
  • U6 CPU RP2A03 (harvested from original Famicom/NES or UA6527 (clone)
  • U10 CIC – The cic can be harvested from the original front loading NES or a Nullcic board can be used. (COMING SOON)
  • TC1 30pf Capacitor
  • RA2 6.8K 4 Resistor Network with common bus )
  • DA1,DA3 Diode Array – DAN601
  • DA2,DA4 Diode Array – UPA64H
  • Q1 – Transistor 2SA937
  • Q2,Q3 – Transistor 2SC2021
  • P6 – 5 pin Connector (harvested from original front loading NES)


The following should beĀ  marked ‘unused’ R14, R16, C6 and C7.

Please note this is an advanced project. There is no tutorial available and no support.

Open Source

This is an open source project by Redherring32. You can find the source files on his github here.

Additional information

Weight0.1875 lbs
Dimensions8 × 5 × 0.1 in


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