The Open-Source Cartridge Reader (OSCR) is a standalone device that can back up physical game cartridges to ROM files, back up game saves stored on game cartridges, restore game saves to physical cartridges (very useful after performing a battery replacement), back up and restore save games stored on N64 Controller Paks (N64 controller required), flash game ROM files onto EEPROM game cartridges, and more.

Supports cartridges for the NES, Famicom, SNES, Super Famicom, N64, Sega Master System, Sega Mega Drive/Genesis, Game Boy, Game Boy Color, and Game Boy Advance.

Backed-up files are stored on an SD card. Self-contained, doesn't require an external computer.

Github: https://github.com/sanni/cartreader

How to take apart an Atari 5200 cartridge.