Games & Preservation

Backing Up NES Games

The Nintendo Entertainment System’s big 72-pin cartridges are the most idiosyncratic of the classic formats — nearly every game carries its own mapper chip, so the reader has to know each cartridge’s wiring. The right tool handles that automatically and turns the game you own into a tiny .nes file. Start with the legal ground rules: own it, dump it yourself, keep it private.

Media
72-pin cartridge (60-pin for the Japanese Famicom).
Hardware
INLretro Dumper-Programmer (~$60) or the Open Source Cartridge Reader with its NES adapter.
Output
.nes (iNES format — the ROM data plus a 16-byte header describing the mapper).
Typical size
40 KB – 512 KB; the largest late-era games reach 1 MB.
Save data
Battery-backed SRAM in RPG-era carts (Zelda, Final Fantasy, Dragon Warrior) — dump these first, the batteries are 35+ years old.
A Nintendo Entertainment System console with controller
The Nintendo Entertainment System. Its games live on ROM chips inside the cartridge shell — data a USB reader can copy out byte-for-byte. Image: Evan-Amos, public domain, via Wikimedia Commons.

What You Need

  • INLretro Dumper-Programmer (~$60, from Infinite NES Lives) — the NES-first choice. It was built by the community that manufactures new NES cartridges, supports the vast majority of mappers, and doubles as a programmer if you ever get into homebrew. Famicom and other console adapters are available.
  • Open Source Cartridge Reader (OSCR) — the do-everything option. The base unit reads SNES, Genesis, N64 and Game Boy carts; add the NES/Famicom adapter to cover this library too. Buy it prebuilt from Save the Hero Builders (~$150 + adapter) or build one yourself from the open design at cartreader.net. It dumps to a microSD card — no computer needed at the cartridge.
  • Isopropyl alcohol and cotton swabs — the famous NES “blinking screen” is dirty contacts, and dirty contacts make corrupt dumps too. Clean every cart before reading it.

Inside the Cartridge

An NES cartridge holds at least two ROM chips: PRG (the program the CPU runs) and CHR (the graphics tiles the PPU draws). The console itself can only address a small window of each — so almost every game beyond the earliest releases adds a mapper: bank-switching hardware (MMC1, MMC3, and dozens more) that swaps larger ROMs through that small window.

This is why NES dumping is special: the reader must recognize the mapper to know how to walk the banks. Good dumpers keep a database of known cartridge boards and handle it silently — but it is also why you should verify your dump afterward.

PRGCHRmapperNES cartridge (72-pin)1USB dumperwalks the mapper banks,adds the iNES header2Game.nes40 KB – 1 MB3OWL media libraryplays in the browser — no console needed
The NES dump: (1) the cartridge’s PRG and CHR ROMs sit behind a mapper chip, (2) the dumper banks through them and prepends the iNES header that tells emulators which mapper to emulate, (3) the result is a small .nes file ready for your library. Diagram: NDEVR.

Dumping, Step by Step

  1. Clean the contacts. Isopropyl alcohol on a swab, both sides of the edge connector, until the swab comes away clean.
  2. Seat the cartridge in the reader. On the INLretro, the desktop app (Windows/Mac/Linux) detects the board type; on the OSCR, pick NES from the menu — it auto-detects the mapper from its database.
  3. Dump the save first if the game has one (see below) — it is the fragile part.
  4. Dump the ROM. Seconds later you have Game.nes.
  5. Verify. Dump a second time and compare, or check the checksum against the No-Intro database. A mismatch usually means dirty contacts — clean and repeat.
★

Famicom and oddball boards

Japanese Famicom carts need only a 60-pin adapter. But a handful of cartridges — bootlegs, and exotic licensed boards — use mappers a dumper may not know. If a dump comes out garbled in the emulator but verifies twice, look the game up in the dumper’s supported-mapper list before blaming the cartridge.

Battery Saves

Carts that let you save — The Legend of Zelda, Final Fantasy, Kirby’s Adventure — hold the save in SRAM kept alive by a CR2032 coin cell that has been discharging since the late 1980s. Both readers above dump the save to a .sav file alongside the ROM, and can write it back after you replace the battery (a simple solder job, or a solderless battery holder from the same shops). Dump the save before anything else — removing the cartridge from a console won’t kill it, but a dead battery will.

Playing Your Backup

Upload Game.nes to your OWL media library and it lands in the Games collection with box art and per-console settings — the player’s NES core runs it in the browser at full speed, with save states synced across your devices, and Play Together can hand player 2’s controller to a friend over a share link. Your backup stays in your own end-to-end encrypted storage.