The old home computers like the C64, PET and VIC20 use a lot of 24 pin ROM chips. Many of those are failing and are often replaced with EPROMs and adapter boards. Those are sometimes hard to acquire, especially for older machines such as the PET. But even more common EPROMs require a dedicated UV eraser, programmer like the Minipro, which all adds up. The OneROM is a versatile replacement for EPROMs based on the RP2350 MCU. It allows for easy reprogramming, multiple ROM images and can replace up to three ROM chips in a single system. Oh, and it’s open source!