Reverse Engineering a Rock-Bottom NES Phone Case

Reverse engineering – A teardown of an ultra-cheap “NES on a chip” phone case reveals how the system’s mystery resin blob hides a VT369 chip with a 4K ROM—and how careful flashing and backlight control can expose its internal data.

It looks like a phone case. It feels like something you’d buy on impulse. But once it’s taken apart, the object turns out to be a full-blown retro computing experiment—built around a bargain version of Nintendo Entertainment System technology and reverse engineered down to the chip level.

The NES was Nintendo’s smash hit console of the 1980s, an international version of their Japanese Famicom system. It wasn’t a particularly complex device, and it drew plenty of clones back in the day. More recently. it’s gotten a second life through “NES on a chip” systems—small. modern implementations that aim to recreate the original experience in far less space.

One of those systems landed inside a cheap phone case. and a recent teardown begins the way these stories often do: with disassembly. Inside, the “brain” isn’t a clean, familiar circuit layout. It’s a mystery resin blob chip. But the teardown doesn’t stop at the visual—there’s also a ROM. which the researcher is able to dump with a little effort.

The next step is where the work gets harder. ROM analysis in place—without removing the relevant parts—requires a lot more effort. The researcher identifies the black blob as a VT369 NES-on-a-chip. then makes a key deduction: some of the device’s code is hidden in the chip’s 4K ROM. From there, the approach becomes more hands-on. Through additional investigation and code injection, the researcher finds a way to control the backlight.

Backlight control turns into the mechanism for extraction. By flashing it on and off, the internal ROM can be dumped. The process is slow and detailed, presented in a very long video, but it builds a complete picture of how these devices operate and why they work at all.

What lingers after the teardown isn’t just the novelty of pulling ROM data from a phone-case NES. It’s the broader lesson the researcher points toward: even if these ICs are “NES” chips. they also carry potential as a more versatile computer beyond Mario. The teardown may not convince anyone to order a NES phone case. but it makes the underlying technology feel less like a gimmick and more like an entry point—small enough to fit anywhere. serious enough to be opened up. understood. and repurposed.

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